Endangered and Threatened Wildlife and Plants; Proposed Endangered Status for 21 Species and Proposed Threatened Status for 2 Species in Guam and the Commonwealth of the Northern Mariana Islands

Federal RegisterOct 1, 2014

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R1-ES-2014-0038: 4500030113]

RIN 1018-BA13

Endangered and Threatened Wildlife and Plants; Proposed Endangered Status for 21 Species and Proposed Threatened Status for 2 Species in Guam and the Commonwealth of the Northern Mariana Islands

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Proposed rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service, propose to list 21 plant and animal species from the Mariana Islands (the U.S. Territory of Guam and the U.S. Commonwealth of the Northern Mariana Islands) as endangered species under the Endangered Species Act of 1973, as amended. We also propose to list two plant species from the Mariana Islands in the U.S. Territory of Guam and the U.S. Commonwealth of the Northern Mariana Islands as threatened species under the Act. If we finalize this rule as proposed, it would extend the Act's protections to these 23 species. The effect of this regulation will be to add these 23 species to the Federal Lists of Endangered and Threatened Wildlife and Plants.

DATES:

We will accept comments received or postmarked on or before December 1, 2014. Comments submitted electronically using the Federal eRulemaking Portal (see

ADDRESSES

below) must be received by 11:59 p.m. Eastern Time on the closing date. We must receive requests for public hearings, in writing, at the address shown in

FOR FURTHER INFORMATION CONTACT

by November 17, 2014.

ADDRESSES:

You may submit comments by one of the following methods:

(1)

Electronically:

Go to the Federal eRulemaking Portal:

http://www.regulations.gov.

In the Search box, enter FWS-R1-ES-2014-0038, which is the docket number for this rulemaking. Then, in the Search panel on the left side of the screen, under the Document Type heading, click on the Proposed Rules link to locate this document. You may submit a comment by clicking on “Comment Now!”

(2)

By Hard Copy:

Submit by U.S. mail or hand-delivery to: Public Comments Processing, Attn: FWS-R1-ES-2014-0038; Division of Policy and Directives Management; U.S. Fish & Wildlife Headquarters, MS: BPHC, 5275 Leesburg Pike, Falls Church, VA 22041-3803.

We request that you send comments

only

by the methods described above. We will post all comments on

http://www.regulations.gov.

This generally means that we will post any personal information you provide us (see

Public Comments

below for more information).

FOR FURTHER INFORMATION CONTACT:

Loyal Mehrhoff, Field Supervisor, Pacific Islands Fish and Wildlife Office, 300 Ala Moana Boulevard, Honolulu, HI 96850; by telephone at 808-792-9400; or by facsimile at 808-792-9581. Persons who use a telecommunications device for the deaf (TDD) may call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

Why we need to publish a rule.

Under the Endangered Species Act of 1973, as amended (Act), if a species is determined to be an endangered or threatened species throughout all or a significant portion of its range, we, the U.S. Fish and Wildlife Service (FWS), are required to promptly publish a proposal in the

Federal Register

and make a determination on our proposal within 1 year. Critical habitat shall be designated, to the maximum extent prudent and determinable, for any species determined to be an endangered or threatened species under the Act. Listing a species as an endangered or threatened species and designations and revisions of critical habitat can only be completed by issuing a rule. We will address designation of critical habitat for these 23 species in a separate rule.

This rule will

propose the listing of 23 species from the Mariana Islands as endangered or threatened species. Twenty-one of these species are proposed as endangered species (12 plants:

Bulbophyllum guamense

(cebello halumtano),

Dendrobium guamense

(no common name (NCN)),

Eugenia bryanii

(NCN),

Hedyotis megalantha

(paudedo),

Heritiera longipetiolata

(ufa-halumtano),

Maesa walkeri

(NCN),

Phyllanthus saffordii

(NCN),

Psychotria malaspinae

(aplokating-palaoan),

Solanum guamense

(berenghenas halomtano),

Nervilia jacksoniae

(NCN),

Tinospora homosepala

(NCN), and

Tuberolabium guamense

(NCN)); and 9 animals: the Pacific sheath-tailed bat (

Emballonura semicaudata rotensis;

liyang), Slevin's skink (

Emoia slevini;

guali'ek halomtano), the Mariana eight-spot butterfly (

Hypolimnas octocula mariannensis;

NCN), the Mariana wandering butterfly (

Vagrans egistina;

NCN), the Rota blue damselfly (

Ischnura luta;

NCN), the fragile tree snail (

Samoana fragilis;

akaleha), the Guam tree snail (

Partula radiolata;

akaleha), the humped tree snail (

Partula gibba;

akaleha), and Langford's tree snail (

Partula langfordi;

akaleha)). Two plant species (

Cycas micronesica

(fadang) and

Tabernaemontana rotensis

(NCN)) are proposed for listing as threatened species. Seven of these 23 species (1 bat, 2 butterflies, and 4 tree snails) are candidate species for which we have on file sufficient information on biological vulnerability and threats to support preparation of a listing proposal, but for which development of a listing regulation had been previously precluded by other higher priority listing activities. This rule will reassess all available information regarding status of and threats to these seven species. Sixteen of the 23 species (14 plant species and 2 animal species (Slevin's skink and Rota damselfly)) are Mariana Islands species for which we have sufficient information on biological vulnerabilities and threats to propose for listing as endangered or threatened, but which have not been previously recognized as candidate species.

The basis for our action.

Under the Act, we can determine that a species is an endangered or threatened species based on any of five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) Overutilization for commercial, recreational, scientific, or educational purposes; (C) Disease or predation; (D) The inadequacy of existing regulatory mechanisms; or (E) Other natural or manmade factors affecting its continued existence. As described in this document, these 23 species are experiencing population-level impacts as the result of the following current and ongoing threats:

• Habitat loss and degradation due to development, military activities, and urbanization; nonnative feral ungulates (hoofed mammals, for example, deer, pigs, and water buffalo) and nonnative plants; rats; snakes; wildfire; typhoons; water extraction, and climate change.

• Predation or herbivory by nonnative feral ungulates, rats, snakes, monitor lizards, slugs, flatworms, ants, and wasps.

• Inadequate existing regulatory mechanisms to prevent the introduction and spread of nonnative plants and animals.

• Ordnance and live-fire from military training, recreational vehicles,

and vulnerability to extinction due to small numbers of individuals and populations.

As a consequence of these threats, we propose to list 2 of these species as threatened species, and 21 of these species as endangered species. We, therefore, propose adding these 23 Mariana Islands species to the Federal Lists of Endangered and Threatened Wildlife and Plants.

We will seek peer review.

We will seek comments from independent specialists to ensure that our designation is based on scientifically sound data, assumptions, and analyses. We will invite these peer reviewers to comment on our listing proposal. Because we will consider all comments and information received during the comment period, our final determinations may differ from this proposal.

Information Requested

Public Comments

We intend that any final action resulting from this proposed rule will be based on the best scientific and commercial data available and be as accurate and as effective as possible. Therefore, we request comments or information from the public, including landowners, land managers, and residents of the U.S. Territory of Guam (Guam) and the U.S. Commonwealth of the Northern Mariana Islands (CNMI), the scientific community, industry, or any other interested parties concerning this proposed rule. We particularly seek comments concerning:

(1) The biology, range, and population trends of these species, including:

(a) Biological or ecological requirements, including habitat requirements for feeding, breeding, and sheltering;

(b) Genetics and taxonomy;

(d) Historical and current population levels, and current and projected trends; and

(e) Past and ongoing conservation measures for these species, their habitats, or both.

(2) Factors that may affect the continued existence of these species, which may include habitat modification or destruction, overutilization, disease, predation, the inadequacy of existing regulatory mechanisms, or other natural or manmade factors.

(3) Biological, commercial trade, or other relevant data concerning any threats (or lack thereof) to these species and existing regulations that may be addressing those threats.

(4) Additional information concerning the historical and current status, range, distribution, and population size of these species, including the locations of any additional populations of these species.

(5) Any information regarding the taxonomy of

Tinospora homosepala,

with particular regard to the question of whether

T. homosepala

may be the same species as the more common

T. glabra,

or is a variety of that species.

Please include sufficient information with your submission (such as scientific journal articles or other publications) to allow us to verify any scientific or commercial information you include.

Please note that submissions merely stating support for or opposition to the action under consideration without providing supporting information, although noted, will not be considered in making a determination, as section 4(b)(1)(A) of the Act directs that determinations as to whether any species is a threatened or endangered species must be made “solely on the basis of the best scientific and commercial data available.”

You may submit your comments and materials concerning this proposed rule by one of the methods listed in

ADDRESSES

. We request that you send comments

only

by the methods described in

ADDRESSES

If you submit information via

http://www.regulations.gov,

your entire submission—including any personal identifying information—will be posted on the Web site. If your submission is made via a hardcopy that includes personal identifying information, you may request at the top of your document that we withhold this information from public review. However, we cannot guarantee that we will be able to do so. We will post all hardcopy submissions on

http://www.regulations.gov.

Please include sufficient information with your comments to allow us to verify any scientific or commercial information you include.

Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection on

http://www.regulations.gov,

or by appointment, during normal business hours, at the U.S. Fish and Wildlife Service, Pacific Islands Fish and Wildlife Office (see

FOR FURTHER INFORMATION CONTACT

Public Hearing

Section 4(b)(5) of the Act provides for one or more public hearings on this proposal, if requested. Requests must be received within 45 days after the date of publication of this proposed rule in the

Federal Register

. Such requests must be sent to the address shown in

FOR FURTHER INFORMATION CONTACT

. We will schedule public hearings on this proposal, if any are requested, and announce the dates, times, and places of those hearings, as well as how to obtain reasonable accommodations, in the

Federal Register

and local newspapers at least 15 days before the hearing.

Peer Review

In accordance with our joint policy on peer review published in the

Federal Register

on July 1, 1994 (59 FR 34270), we have sought the expert opinions of 10 appropriate and independent specialists regarding this proposed rule. The purpose of peer review is to ensure that our listing determinations are based on scientifically sound data, assumptions, and analyses. The peer reviewers have expertise about one or more of the 23 species' biology, habitat, life-history needs, and vulnerability to threats, which will inform our determination. We invite comment from the peer reviewers during this public comment period. A copy of our peer review plan is available for public review at

http://www.fws.gov/pacific/informationquality

Previous Federal Actions

Seven of the 23 species proposed for listing as endangered species are candidate species (77 FR 70103; November 22, 2013). Candidate species are those taxa for which the U.S. Fish and Wildlife Service (Service) has sufficient information on their biological status and threats to propose them for listing under the Act, but for which the development of a listing regulation has been precluded to date by other higher priority listing activities. The current candidate species addressed in this proposed listing rule include the following seven animal species: the Pacific sheath-tailed bat (

Emballonura semicaudata rotensis

), the Mariana eight-spot butterfly (

Hypolimnas octocula marianensis

), the Mariana wandering butterfly (

Vagrans egistina

), the fragile tree snail (

Samoana fragilis

), the Guam tree snail (

Partula radiolata

), the humped tree snail (

Partula gibba

), and Langford's tree snail (

Partula langfordi

). The candidate status of these species was most recently reaffirmed in the November 22, 2013, Review of Native Species that are Candidates for Listing as Endangered or Threatened (CNOR) (77 FR 70103).

On May 4, 2004, the Center for Biological Diversity petitioned the Secretary of the Interior to list 225 species of plants and animals, including the 7 candidate species listed above, as endangered or threatened under the provisions of the Act. Since then, we

have published our annual findings on the May 4, 2004, petition (including our findings on the seven candidate species listed above) in the CNORs dated May 11, 2005 (70 FR 24870), September 12, 2006 (71 FR 53756), December 6, 2007 (72 FR 69034), December 10, 2008 (73 FR 75176), November 9, 2009 (74 FR 57804), November 10, 2010 (75 FR 69222), October 26, 2011 (76 FR 66370), November 21, 2012 (77 FR 69994), and November 22, 2013 (77 FR 70103). This proposed rule constitutes a further response to the 2004 petition.

In addition to the 7 candidate species, we are proposing to list 16 additional species that occur in the Mariana Islands as endangered or threatened species, including 14 plants (

Bulbophyllum guamense, Cycas micronesica,

Dendrobium guamense, Eugenia bryanii,

Hedyotis megalantha, Heritiera longipetiolata,

Maesa walkeri, Nervilia jacksoniae,

Phyllanthus saffordii, Psychotria malaspinae,

Solanum guamense, Tabernaemontana rotensis,

Tinospora homosepala,

and

Tuberolabium guamense

) and 2 animals (Slevin's skink (

Emoia slevini

) and the Rota blue damselfly (

Ischnura luta

)). Three of these plant species,

Heritiera longipetiolata, Maesa walkeri,

and

Psychotria malaspinae,

have been identified as the “rarest of the rare” Mariana plant species and in need of immediate conservation under the multiagency (Federal and Territorial) Guam Plant Extinction Prevention Program (GPEPP). The goal of GPEPP is to prevent the extinction of plant species that have fewer than 200 individuals remaining in the wild on the island of Guam (GPEPP 2014, in litt.). We believe these 14 plants and 2 animal species warrant listing under the Act for the reasons discussed in the “Summary of Factors Affecting the Species” section (below). Because these 16 species occur within 2 of the same ecosystems as the 7 candidate species, and share common threats with them, we have included them in this proposed rule to provide them with protection under the Act in an expeditious manner.

We will be publishing a proposal to address critical habitat for the 23 Mariana Islands species under the Act in the near future.

Background

Mariana Islands Species Addressed in this Proposed Rule

Table 1 below provides the scientific name, common name, listing status, and range (islands on which the species is found) for the 23 Mariana Islands species that are addressed in this proposed rule.

Table 1—The 23 Species Addressed in This Proposed Rule

Scientific name

Common name(s)

Listing status

Range

Plants

Bulbophyllum guamense

cebello halumtano

Proposed-Endangered

Guam, Rota, Saipan (H), Pagan (H).

Cycas micronesica

fadang

Proposed-Threatened

Guam, Rota, Pagan, Palau,* Yap.*

Dendrobium guamense

NCN

Proposed-Endangered

Guam, Rota, Tinian (H), Saipan (H).

Eugenia bryanii

NCN

Proposed-Endangered

Guam.

Hedyotis megalantha

paudedo

Proposed-Endangered

Guam.

Heritiera longipetiolata

ufa-halomtano

Proposed-Endangered

Guam, Saipan, Tinian, Rota (H).

Maesa walkeri

NCN

Proposed-Endangered

Guam, Rota.

Nervilia jacksoniae

NCN

Proposed-Endangered

Guam, Rota.

Phyllanthus saffordii

NCN

Proposed-Endangered

Guam.

Psychotria malaspinae

aplokating-palaoan

Proposed-Endangered

Guam.

Solanum guamense

berenghenas halomtano

Proposed-Endangered

Guam, Rota (H), Tinian (H), Saipan (H), Asuncion (H), Guguan (H), Maug (H).

Tabernaemontana rotensis

NCN

Proposed-Threatened

Guam, Rota.

Tinospora homosepala

NCN

Proposed-Endangered

Guam.

Tuberolabium guamense

NCN

Proposed-Endangered

Guam, Rota, Aguiguan (H), Tinian (H).

Animals

Emballonura semicaudata rotensis

Pacific sheath-tailed bat, liyang

, payesyes

, pai scheei

Proposed-Endangered (C)

Aguiguan, Guam (H), Rota (H), Tinian (H), Saipan (H), Anatahan (H*), Maug (H*).

Emoia slevini

Slevin's skink, Marianas Emoia, guali'ek halom tano

Proposed-Endangered

Guam (Cocos Island), Alamagan, Asuncion, Guguan, Pagan, Sarigan.

Hypolimnas octocula mariannensis

Mariana eight-spot butterfly

Proposed-Endangered (C)

Guam, Saipan (H).

Vagrans egistina

Mariana wandering butterfly

Proposed-Endangered (C)

Rota, Guam (H).

Ischnura luta

Rota blue damselfly

Proposed-Endangered

Rota.

Partula gibba

humped tree snail, akaleha'

Proposed-Endangered (C)

Guam, Rota, Aguiguan, Alamagan, Pagan, Sarigan, Saipan, Tinian (H), Anatahan (H).

Partula langfordi

Langford's tree snail, akaleha'

Proposed-Endangered (C)

Aguiguan.

Partula radiolata

Guam tree snail,

akaleha'

Proposed-Endangered (C)

Guam.

Samoana fragilis

fragile tree snail, akaleha'

Proposed-Endangered (C)

Guam, Rota.

NCN = no common name.

H) = historical occurrence.

(H*) = possible historical occurrence.

Ch = Chamorro name.

Ca = Carolinian name.

* = range outside of the Mariana Islands.

The Mariana Islands

Geography

The Mariana Islands is a longitudinallyarranged archipelago consisting of 15 main islands and various smaller islets located in western Micronesia between latitudes 21° and 13° N and longitudes 144° and 146° E. The Mariana Islands vary in age, between 5 million years old in the north and 50 million years old in the south. The archipelago was formed by the collision of the Pacific and Philippine tectonic plates at the Mariana Trench, which resulted in volcanic activity that built up a chain of mountains protruding from the sea floor (see Figure 1) (Raulerson and Rinehart 1992, p. 3; Scripps Institution of Oceanography (SIO) 2014, in litt.). Scientists biogeographically separate the Mariana Islands into the “northern” and “southern” islands based on geological time of formation and associated substratum (Fosberg et al. 1975, pp. 1−5; Mueller-Dombois and Fosberg 1998, p. 241). The primarily volcanic northern islands include Farallon de Medinilla, Anatahan, Sarigan, Guguan, Alamagan, Pagan, Agrihan, Asuncion, Maug, and Uracas, while the limestone and volcanic southern islands include Guam, Rota, Aguiguan, Tinian, and Saipan. The northern islands of Anatahan, Guguan, Alamagan, Asuncion, Pagan, and Uracas are still volcanically active. Only the southern islands of Guam, Cocos Island, Rota, Tinian, and Saipan are regularly inhabited by humans; all of the other Mariana Islands are considered uninhabited, although some (e.g., Aguiguan, Pagan) may be visited on occasion.

BILLING CODE 4310-55-P

EP01OC14.000

BILLING CODE 4310-55-C

Geology

The substratum of the younger northern islands is of volcanic origin, while the substratum of the older southern islands is coral limestone (Mueller-Dombois and Fosberg 1998, p. 241). The limestone substratum of the southern islands is composed of ancient coral reef limestone that developed as the islands rose from the ocean floor and eventually above sea level (Berger et al. 2005, p. 9). The northern islands contain very little limestone substratum

due to their young age and because many of them (Uracas, Pagan, Asuncion, Guguan and Anatahan) remain volcanically active (Ohba 1994, p. 14; U.S. Geological Survey (USGS) 2006, in litt.). The northern islands are composed of black basalts and are typically cone-shaped volcanoes with steep slopes, many of which have eroded into steep ravines often widened by erosion (Ohba 1994, p. 14). Areas of exposed weathered volcanic substratum can be found on the southern islands, particularly on the southern half of Guam, in strong contrast to the predominant karst limestone composition of the northern half of the island (Mueller-Dombois and Fosberg 1998, p. 241).

Vegetation

Both the intentional and inadvertent introduction of alien plant and animal species has contributed to the reduction in range of native vegetation throughout the Mariana Islands (throughout this rule, the terms “alien,” “feral,” “nonnative,” and “introduced” all refer to species that are not naturally native to the Mariana Islands). Currently, most of the extant native vegetation on the islands persists on rugged karst or steep limestone slopes and precipitous cliffs, ridgelines, valleys, and other regions where unsuitable topography prevents urbanization and agricultural development, or where inaccessibility limits encroachment by nonnative plants and grazing by feral ungulates (Amidon 2000, p. 5; Berger et al. 2005, pp. 37, 44-45).

Hydrology

There are no year-round surface water sources in the northern islands, with the exception of two small lakes on the island of Pagan. The southern islands, in contrast, exhibit multiple year-round surface water sources including wetlands and streams on Saipan, two perennial streams and two springs on Rota, a small wetland on Tinian, and several wetlands, rivers, and streams on the volcanic portions of southern Guam, particularly in the Tolofofo River region (CNMI Statewide Assessment and Resource Strategy Council (CNMI-SWARS) 2010, pp. 9-10, 30, 32; Mueller-Dombois and Fosberg 1998, pp. 248, 254, 260, 266, 269; SIO 2014, in litt.).

Climate

Their relatively low elevation above sea level (the highest point in the chain is Mt. Agrihan on Agrihan at 3,166 ft (965 m)), juxtaposed with their close proximity to the equator, insulate the Mariana Islands from seasonal variation in weather and climate. The entire archipelago is defined as the “tropical rainforest climate” according to the Koeppen climate classification (Ohba 1994, p. 16); however, there are very few year-round meteorological weather stations in the Mariana Islands, resulting in limited available meteorological data. Additional data has been collected from Iwo-Jima from which patterns are collectively extrapolated across the Mariana archipelago (Ohba 1994, pp. 15-16).

The Mariana archipelago exhibits two distinct seasons, a notably wetter season from July through October, and a drier season from November through June, with April characteristically being the driest month out of the year (Ohba 1994, p. 16; Mueller-Dombois and Fosberg 1998, p. 241). Precipitation averages 96 in (218 cm) per year, dependent in part upon elevation. Some of the tallest peaks across the islands experience frequent cloud cover, particularly the northern island summits of Anatahan, Alamagan, Pagan, and Sarigan (Dahl 1980, pp. 22, 64; Ohba 1994, pp. 18, 41, 48). Stone (1970, p. 12) observed the southern Mariana Islands (from Anatahan southward) to be warmer than the northern islands.

The Mariana Islands receive relatively constant trade winds with a weak westerly monsoon influence in summer months (Mueller-Dombois and Fosberg 1998, p. 241). Storms and typhoons originating from the southeast and east occur frequently with an average of one typhoon per year affecting the Mariana Islands (Mueller-Dombois and Fosberg 1998, p. 241).

Biogeography

In general, the younger, northern islands, particularly the five active volcanic islands (Uracas, Pagan, Asuncion, Guguan, and Anatahan), support fewer species and ecosystem types than the southern islands, due primarily to factors including age, time since last eruption, island size, and highest point of elevation (Ohba 1994, pp. 15-18; Mueller-Dombois and Fosberg 1998, p. 241). Historically, volcanic eruptions have proved very disruptive to the ecology of the more northern Mariana Islands when they occur (USGS 2006, in litt.; Zoology Unlimited, LLC (Limited Liability Company) 2013, pp. 9-11). For example, in May 2003, the island of Anatahan experienced a powerful and explosive eruption that destroyed 80 to 90 percent of the island's forest cover and was believed to have caused the extirpation of the Mariana fruit bat (

Pteropus mariannus mariannus

) and Micronesian megapode (

Megapodius laperouse laperouse

) (Zoology Unlimited, LLC. 2013, pp. 10-11). Fortunately, these two species have been observed on Anatahan in recent years, albeit in low numbers (Zoology Unlimited, LLC. 2013, pp. 10-11).

The cumulative literature portrays Guam and Rota, in the southern part of the archipelago, as the most species-rich of the Mariana Islands. Mueller-Dombois and Fosberg (1998, p. 243) conducted one of the most comprehensive vegetation analyses of the Mariana Islands (building upon their previous works and those of Stone (1970, 659 pp.), Ohba (1994, p. 18), and many others) and observed that, although the primary substratum differs between the northern and southern islands (

e.g.,

volcanic versus limestone, respectively), the physical nature of the substratum may be of equal or more importance than the chemical nature in determining vegetation patterns. For example, some areas covered by rough lava flows found on the northern islands exhibit convergent forest type compared to forests found on the karst limestone in the southern islands (Mueller-Dombois and Fosberg 1998, pp. 243-245). Additionally, grassland (

i.e.,

savanna) species in the northern islands overlap with species found in the southern islands grasslands, although species richness is greater on the southern islands (Mueller-Dombois and Fosberg 1998, p. 241). The northern islands are predominantly primary grasslands (colonized relatively recently after volcanic activity) with areas of secondary forest. Conversely, the southern islands are predominantly primary and secondary forests with secondary grasslands, a situation that likely arose from grassland expansion through agricultural burning and clearing (Mueller-Dombois and Fosberg 1998, p. 241).

Micronesia, together with Polynesia, is described as the Polynesia-Micronesia Hotspot, meaning that these island groups contain an exceptional concentration of endemic (found nowhere else in the world) species, and are currently experiencing exceptional habitat loss (Myers et al. 2000, pp. 853-855).

Pre-Historical Human Impact

Archaeological evidence indicates that the Mariana Islands had been settled approximately 2,000 B.C. by the pre-contact Chamorro people, who migrated from Southeast Asia (SIO 2014, in litt.). The Chamorro people introduced to the islands a variety of food plants including rice, breadfruit, sugar cane, bananas, coconuts, and taro (Stone 1970, pp. 182, 200). The exact

extent to which these early settlers modified the landscape is unknown; however, it is believed to be not insignificant (Fosberg 1960, pp. 36, 42-43). These environmental impacts may parallel those documented in the Hawaiian Islands by early Hawaiian settlers; however, early Chamorro impacts in the Mariana Islands are not as well documented.

The Chamorro established their largest settlements in the southern islands including Guam, Rota, and Saipan (Russell 1998, p. 87). However, multiple smaller settlements existed in the northern islands and these were likely dependent in part on the larger communities in the relatively resource-rich southern islands (Russell 1998, p. 84). Researchers estimate that 100,000 to 150,000 Chamorro may have inhabited these islands, a number that declined to below 5,000 individuals just a few hundred years after European contact due to introduced diseases and other factors (SIO 2014, in litt.).

Historical and Ongoing Human Impacts

After the initial Chamorro modifications for agriculture and villages, the flora and fauna on the Mariana Islands continued to undergo alterations due not only to ongoing volcanic activity in the northern islands, but also to land use activities and nonnative species introduced by European colonialists. The arrival of the Spanish in 1591 further imposed degradation of the ecosystems of the Mariana Islands with the introduction of numerous nonnative animals and plants. The Spanish occupied the Mariana Islands for nearly 300 years (SIO 2014, in litt.). In 1899, Spain sold the Mariana Islands to Germany, with the exception of Guam, which was ceded to the United States as a result of the Spanish-American war (SIO 2012, in litt.; Encyclopedia Britannica 2014, in litt.).

The German administration altered the forest ecosystem on Rota, Saipan, and Tinian, and on some of the northern islands, by means of

Cocos nucifera

(coconut) farming, which was encouraged for the production of copra (the dried fleshy part of a coconut used to make coconut oil) (Russell 1998, pp. 94-95). Upon the start of World War I, the Japanese quickly took over German occupied islands and accelerated the alteration of the landscape by clearing large areas of native forest on Rota, Saipan, and Tinian for growing

Saccharum officinarum

(sugarcane) and building associated refineries and for planting

Acacia confusa

(sosugi) to provide fuel wood (CNMI-SWARS 2010, pp. 6-7). The Japanese drastically altered the islands of Rota, Saipan, and Tinian, leaving little native forest. Military activities during World War II further altered the landscape on Saipan and Tinian. Rota was a notable exception, left relatively untouched (CNMI-SWARS 2010, p. 7). Japan also occupied Guam at the onset of World War II; however, by 1944 the U.S. neutralized the Mariana Islands with the recapture of Saipan, Tinian and Guam (Encyclopedia Britannica 2014, in litt.). Since World War II, the U.S. military has developed a strong presence in the Mariana Islands, particularly on the island of Guam, where both the U.S. Navy and U.S. Air Force operate large military installations. The island of Farallon de Medinilla is used for military ordnance training (Berger et al. 2005, p. 130).

Currently, the U.S. Department of Defense is implementing a project referred to as the “Guam and Commonwealth of the Northern Mariana Islands Military Relocation” (Joint Guam Program Office (JGPO)-Naval Facilities Engineering Command, Pacific (JGPO-NavFac, Pacific) 2010a, p. ES-1; JGPO-NavFac, Pacific 2013, pp. 1-1—1-3). This military relocation proposes: (1) the relocation of a portion of the U.S. Marine Corps (Marine Corps) currently in Okinawa, Japan, which consists of up to 5,000 Marines and their 1,300 dependents, as revised in the Draft Supplemental Environmental Impact Statement (SEIS) (NavFac Engineering Command Pacific 2014, p. ES-3), in addition to the development and construction of facilities and infrastructure to support training and operations on Guam and Tinian for the relocated Marines; (2) the construction of a deep-draft wharf with shoreside infrastructure at Apra Harbor, Guam, to support the U.S. Navy (Navy) transiting nuclear-powered aircraft carrier; and (3) the development of facilities and infrastructure on Guam to support the relocation of military personnel and their dependents to establish and operate a U.S. Army (Army) and Missiles Defense Task Force (JGPO-NavFac, Pacific 2010a, p. ES-7).

Both Guam and Tinian are located within the Mariana Islands Range Complex, an area used by the Department of Defense (DOD) for readiness training (JGPO-NavFac, Pacific 2010a, pp. ES-2—ES-3). The northern two-thirds of Tinian are leased to the DOD, and the development of these lands will negatively impact the habitat of 1 of the 23 species in the forest ecosystem (

Heritiera longipetiolata

). The draft 2014 SEIS focuses on the change to the preferred alternatives identified in the 2010 Final EIS (NavFac Engineering Command Pacific 2014, p. ES-1). The preferred alternative sites on Guam for the implementation of the Marine relocation efforts and development of a live-fire training range complex now include Alternative A Finegayan and Alternative 5 Northwest Field on Andersen Air Force Base (AFB), where, in total, 18 of the 23 species or their habitat are known to occur (13 of the 14 plants:

Bulbophyllum guamense, Cycas micronesica, Dendrobium guamense, Eugenia bryanii, Hedyotis megalantha, Heritiera longipetiolata, Maesa walkeri, Nervilia jacksoniae, Phyllanthus saffordii, Psychotria malaspinae, Solanum guamense, Tabernaemontana rotensis,

and

Tuberolabium guamense;

and 5 of the 9 animals: the Mariana eight-spot butterfly, the Mariana wandering butterfly, the Guam tree snail, the humped tree snail, and the fragile tree snail) (NavFac Engineering Command Pacific 2014, pp. ES-18—ES-22). The draft SEIS describes: (1) a more moderate construction activity over 13 years instead of a 7-year intense construction boom; (2) a significant reduction in peak and steady state population increases, from more than 79,000 new Guam residents down to 7,400 new residents; (3) a reduction in the project area at Finegayan from 2,580 ac (1,044 ha) to 1,452 ac (588 ha); (4) no new land acquisition; (5) a reduction in project area at Northwest Field (instead of Route 15); and (6) an overall decrease in power and water demands (NavFac Engineering Command Pacific 2014, p. ES-3).

In conjunction with the relocation efforts discussed above, the U.S. military is planning to improve existing and develop new live-fire military training areas on the islands of Tinian and Pagan (JPGO-NavFac, Pacific 2010a, pp. ES-5, ES-16-17, ES 19-20, ES-40; CJMT EIS-OEIS (see below)). The Marine Corps (the Executive Agent designated by the U.S. Pacific Command) recently published their “Commonwealth of the Northern Mariana Islands Joint Military Training Environmental Impact Statement—Overseas Environmental Impact Statement (CJMT EIS-OEIS at

http://www.cnmijointmilitarytrainingeis.com/about

). The CJMT EIS-OEIS Final Scoping Summary Report informs the public that the military plans to maximize use of DOD-leased lands within CNMI, specifically Tinian and Pagan. The live-fire training range project area on Tinian overlaps with the relocation effort areas discussed above (the northern two-thirds of the island). Likewise, the live-fire training range

project will negatively impact the plant species

Heritiera longipetiolata,

as discussed above. On Pagan, both Alternative 1 and Alternative 2 claim the entire island as a live-fire training area (NavFac Engineering Command Pacific 2014, p. 13). In addition, the live-fire training range project proposes the designation of special use air and sea spaces around the entire islands of Pagan, Tinian, and Aguiguan (just south of Tinian), and most of Saipan (north of Tinian). If the entire island of Pagan is used as a live-fire training range area, it would negatively impact 4 of the 23 species (

Cycas micronesica,

Slevin's skink, humped tree snail, and habitat for

Bulbophyllum guamense

) and their habitat in the forest ecosystem.

In addition to military spending, Guam's economy depends on tourism. More than 1 million tourists visit Guam annually, mostly arriving from Japan, Korea, and other Asian countries. In the early 1960s, military contributions to Guam's economy approached 60 percent, with tourism adding almost another 30 percent. There was a downturn in military presence and tourism in the 70s and 80s; however, recently, with the projected increase in military employees and their dependents, and with Guam seeking a “no visa required” status for visitors from Russia and China, monitoring of sea ports and airports against inadvertent introduction of harmful and invasive species is especially important (

http://www.guamvisitorsbureau.com/,

accessed April 25, 2014;

http://guampedia.com/evolution-of-the-tourism-industry-on-guam-2/#toc-consequences-and-conclusions,

accessed April 25, 2014) (see

Factor D. The Inadequacy of Existing Regulatory Mechanisms

Political Division

Micronesia consists of several island groups: (1) Mariana Islands (collectively the U.S. Commonwealth of the Northern Mariana Islands (CNMI) and the U.S. Territory of Guam); (2) the Federated States of Micronesia, including the Caroline Islands, Yap, Chuuk, Pohnpei, and Kosrae and the Republic of Palau, the Republic of Kiribati, the Republic of the Marshall Islands, Nauru, and Wake Island.

Islands in the Mariana Archipelago

A brief summary of each island in the Mariana archipelago, from south to north, follows below (for detailed information see Stone 1970, 75 pp.; Falanruw et al. 1989, 11 pp.; Ohba 1994, 56 pp.; Mueller-Dombois and Fosberg 1998, 32 pp.). Here we describe each of the islands in the Mariana archipelago, even if the species addressed in this proposed rule do not currently occur there, or were not found there historically, to provide the reader context for understanding various issues discussed in this document or in subsequent rulemakings that may make reference to the various islands.

Guam

Guam is the largest and southernmost island of the Mariana Islands. It is nearly 31 miles (mi) (50 kilometers (km)) long and from 4 to 9 mi (7 to 15 km) wide, with a peak elevation of 1,332 feet (ft) (406 meters (m)) at Mt. Lamlam (Muller-Dombois and Fosberg 1998, p. 269). Guam is located in the northwestern Pacific Ocean, 1,200 mi (1,930 km) east of the Philippines, 3,500 mi (5,632 km) west of the Hawaiian Islands, and 54 mi (87 km) south of Rota. The northern and southern regions of the island show marked contrast due to their geologic history. The northern region is an extensive, upraised, terraced, limestone plateau or “mesa” between 300 and 600 ft (90 and 183 m) above sea level interrupted by a few low hills, of which two (Mataguac and Mt. Santa Rosa) are volcanic in nature; others are exclusively coralline limestone (e.g., Barrigada Hill and Ritidian Point (Stone 1970, p. 12)). The southern region is primarily volcanic material (e.g., basalts) with several areas capped by a layer of limestone (Stone 1970, p. 12).

Of all the Mariana Islands, Guam contains the most extensive stream and drainage systems, particularly in the Talofofo Region (Stone 1970, p. 13; Muller-Dombois and Fosberg 1998, p. 269). Fairly extensive wetland areas are located on both coasts of the southern region as well as the higher elevation Agana Swamp located in the middle of the island. Guam is also the most populated of all the Mariana Islands, with more than 180,000 residents. Guam has experienced impacts from at least 4,000 years of human contact, starting with the Chamorro, followed by the Spanish, Germans, Japanese, and Americans (see “Pre-Historical Human Impact” and “Historical and Ongoing Human Impacts,” above). World War II and subsequent U.S. military activity have also negatively impacted natural habitats on Guam; however, the buffer zones around the U.S. Navy and Air Force bases on Guam and conservation areas designated on these bases support some of the rarest species. There are three conservation areas designated by the Guam Department of Aquatic and Wildlife Resources (GDAWR): (1) Anao Conservation Area; (2) Bolanos Conservation Area; and, (3) Cotal Conservation Area (GDAWR 2006, p. 39; Sablan Environmental, Inc. 2008, p. 3). Guam supports the forest, savanna, stream, and cave ecosystems (see “Mariana Islands Ecosystems,” below). Twenty of the 23 species addressed in this proposed rule occur on Guam (all 14 plants:

and

Tuberolabium guamense;

and 6 of the 9 animals: Slevin's skink (Cocos Island, off Guam), the Mariana eight-spot butterfly, the Mariana wandering butterfly, the Guam tree snail, the humped tree snail, and the fragile tree snail. The Pacific sheath-tailed bat occurred on Guam historically.

Rota

Just northeast of Guam (36 mi; 58 km) and southwest of Aguiguan (47 mi; 76 km), Rota is the fourth largest island in the Mariana Islands, measuring 33 square miles (mi

) (96 square kilometers (km

)) in land area (Mueller-Dombois and Fosberg 1998, p. 265; CNMI-SWARS 2010, p. 6). The highest point on the island is Mount Sabana or the “Sabana plateau,” at just over 1,600 ft (488 m) (Mueller-Dombois and Fosberg 1998, p. 265). The Sabana plateau is characterized by a savanna ringed by forest that extends onto the surrounding karst limestone cliffs and down the rugged slopes that encircle all sides of the Sabana (Mueller-Dombois and Fosberg 1998, pp. 265-266). Rota consists primarily of terraced limestone surrounding a volcanic core that protrudes from the topmost plateau, or Sabana. The Sabana is noticeably wetter than the rest of the island and is the only location known to support all four orchids proposed for listing as endangered or threatened species in this rule (

Bulbophyllum guamense, Dendrobium guamense, Nervilia jacksoniae,

and

Tuberolabium guamense

) (Harrington et al. 2012, in litt.).

Rota has experienced land alterations since the arrival of the first Chamorro more than 4,000 years ago. When the Mariana Islands were occupied by the Japanese (1914-1944) they cleared forest areas to plant large sugarcane plantations and conducted phosphate mining on the Sabana plateau (Amidon 2000, pp. 4-5; Engbring 1986, pp. 10, 27). Although Rota was never invaded during World War II, it was heavily bombed by U.S. military forces

(Engbring et al. 1986, pp. 8, 11). Rota has a population of approximately 3,000 people. In recent years, three terrestrial conservation areas have been designated on Rota by the CNMI Department of Land and Natural Resources: (1) The Sabana Heights Wildlife Conservation Area; (2) I-Chenchon Park Wildlife Conservation Area and Bird Sanctuary; and, (3) Wedding Cake Mountain Wildlife Conservation Area (Berger et al. 2005, p. 14).

Rota supports the forest, savanna, stream, and cave ecosystems. Eleven of the 23 species addressed in this proposed rule currently occur on Rota (7 of the 14 plants:

Bulbophyllum guamense, Cycas micronesica, Dendrobium guamense, Maesa walkeri, Nervilia jacksoniae, Tabernaemontana rotensis,

and

Tuberolabium guamense;

and 4 of the 9 animals: the Mariana wandering butterfly, the Rota blue damselfly, the fragile tree snail, and the humped tree snail). The plants

Heritiera longipetiolata

and

Solanum guamense

and the Pacific sheath-tailed bat were known from Rota historically.

Aguiguan

Aguiguan is known as “Goat Island” due to the presence of a large feral goat population (Engbring et al. 1986, p. 8). Located approximately 8 km (5 mi) southwest of Tinian, Aguiguan is a small uninhabited island measuring 7 mi

(18 km

) in land area with a peak elevation of 515 ft (157 m) at Mt. Alutom (CNMI-SWARS 2010, p. 6). This island was historically inhabited by the Chamorro people (Russell 1998, pp. 90-91). Aguiguan is entirely limestone, with very steep cliffs fringing nearly the entire island, making access difficult (Berger et al. 2005, p. 36). There are no streams on the island (Engbring et al. 1986, p. 8). During the Japanese occupation, large areas of native forest were cleared for sugarcane plantations, a large runway and other war-related structures (Engbring et al. 1986, p. 8; Mueller-Dombois and Fosberg 1998, p. 264). Ecosystem types on Aguiguan include forest and cave. Three of the 23 species addressed in this proposed rule occur on Aguiguan: the Pacific sheath-tailed bat, the humped tree snail, and Langford's tree snail. The plant

Tuberolabium guamense

was known from Aguiguan historically.

Tinian

Located approximately 3 mi (5 km) southeast of Saipan and 7 mi (9 km) north of Aguiguan, Tinian is the third largest island in the Mariana Islands, measuring 40 mi

(101 km

) in area, with a peak elevation of 584 ft (178 m) at Lasso Hill (Engbring et al. 1986, p. 5). The island of Tinian has a population of more than 3,000 residents. Tinian's climate is the same as that of Guam (see

“The Mariana Islands,”

above). The island is predominantly limestone with low-lying plateaus and ridges, and lacks surface streams (Stafford et al. 2005, p. 15; Engbring et al. 1986, p. 5). Two small wetland areas, heavily overgrown with no open water, Hagoi Marsh and Marpo Swamp, serve as a domestic water source (Engbring et al. 1986, p. 5). Tinian has lost most of its primary (native) forest, due initially to clearing for agriculture by the Chamorro, followed by agricultural endeavors of German colonialists in the early 1900s (

e.g.,

coconut plantations) and then by Japanese settlers after 1914 (e.g., sugarcane plantations) (Berger et al. 2005, pp. 36-37). Impacts to Tinian's native vegetation were then compounded by impacts from military activities during World War II (Mueller-Dombois and Fosberg 1998, p. 262; Russell 1998, p. 98; CNMI-SWARS 2010, pp. 6-7, 28-29). Currently, approximately 5 percent of primary (native) forest remains on Tinian (Engbring et al. 1986, p. 25). Tinian supports the forest and cave ecosystems. Tinian currently has no designated conservation areas. One of the 23 species addressed in this proposed rule occurs on Tinian,

Heritiera longipetiolata.

The plants

Dendrobium guamense, Solanum guamense,

and

Tuberolabium guamense,

the Pacific sheath-tailed bat, and the humped tree snail were known from Tinian historically.

Saipan

Located approximately 3 mi (4.5 km) northeast of Tinian, Saipan is the second largest and second most populous of the Mariana Islands, measuring 44 mi

(115 km

) with a peak elevation of 1,555 ft (474 m) at Mt. Tapochau (Mueller-Dombois and Fosberg 1998, p. 256). The island is composed primarily of terraced limestone peaks, with exposed volcanic ridges and slopes (Mueller-Dombois and Fosberg 1998, p. 256). Saipan supported a large population of Chamorro people for thousands of years, followed by the Spanish, Germans, Japanese, and the U.S. military forces, and was also heavily impacted by World War II. Saipan is the site of one of the largest battles in the Pacific between U.S. and Japanese forces. Much of Saipan's forests were destroyed during World War II, with only pockets of native forest surviving (Engbring et al. 1986, pp. 3-5, 10-12; Berger et al. 2005, pp. 38-39). Due to this widespread destruction of native forests and subsequent erosion, the nonnative tree

Leucaena leucocephala

(tangantangan) was seeded for erosion control (Berger et al. 2005, p. 32). Tangantangan is now a dominant tree species on the island, and forms a unique mixed-forest habitat not reported from the other islands (CNMI-SWARS 2010, p. 7). There are four conservation areas on Saipan: (1) Bird Island Wildlife Preserve; (2) Kagman Wildlife Conservation Area and Forbidden Island Sanctuary; (3) Marpi Forest; and (4) the Saipan Upland Mitigation Bank (Berger et al. 2005, p. 14). Ecosystem types on Saipan include forest, savanna, and cave. One of the 23 species addressed in this proposed rule occurs on Saipan, the humped tree snail. The plants

Bulbophyllum guamense, Dendrobium guamense,

and

Solanum guamense,

the Pacific sheath-tailed bat, and the Mariana eight-spot butterfly were known from Saipan historically.

Farallon de Medinilla

Located approximately 52 mi (83 km) northeast of Saipan, and 33 mi (53 km) south of Anatahan, Farallon de Medinilla (FDM) is a small, uninhabited island measuring less than 1 mi

(3 km

) in area with a peak elevation of 1,047 ft (319 m) (CNMI-SWARS 2010, p. 6). None of the 23 species are currently or historically documented from this island.

Anatahan

Located approximately 23 mi (37 km) south of Sarigan, and 33 mi (53 km) northwest of FDM, Anatahan is an uninhabited volcanic island with recent activity, measuring 12 mi

(31 km

) in land area, and a peak elevation of 2,582 ft (788 m) (Mueller-Dombois and Fosberg 1998, p. 252; CNMI-SWARS 2010, p. 6). This island is believed to have been inhabited by the Chamorro people, if not as a permanent residence, then as a collection site for natural resources (Russell 1998, p. 87). Climate on Anatahan is similar to Guam and the other southern Mariana Islands (see “

The Mariana Islands,

” above); however, being at a more northerly latitude, can be slightly cooler than the islands to the south (Ohba 1994, p. 14). Notable physical features of Anatahan include two volcanoes with an east to west trending summit depression formed by overlapping summit craters (Berger et al. 2005, p. 11). The largest caldera measures 1.5 by 2 mi (2 by 3 km) wide. Between 2003 and 2005, Anatahan erupted several times, with the largest eruption occurring in 2005, covering the island with at least 6 ft (2 m) of volcanic ash and destroying an estimated 98 percent of the forest and

savanna habitat (Berger et al. 2005, p. 11; Kessler 2011, pp. 321, 323). Coconut crabs (

Birgus latro

) and five species of resident land birds were eliminated along with most plants and other animals; however, cats (

Felis catus

), rats (

Rattus

spp.), and monitor lizards (

Varanus indicus

) survived (Kessler 2011, p. 323). Vegetation is slowly recovering, and if cats and rats were eliminated, Anatahan could be a good site for the reintroduction of native species—a “clean slate” (Kessler 2011, pp. 323-324). At this time, none of the 23 species are known to occur on Anatahan; however, the humped tree snail occurred there historically.

Sarigan

Located approximately 40 mi (64 km) south of Guguan and 23 mi (37 km) northeast of Anatahan, Sarigan is an uninhabited, roughly triangular, island measuring 2 mi

(5 km

) in width with a peak elevation of 1,801 ft (549 m) (CNMI-SWARS 2010, p. 6). The island is believed to have been inhabited by the Chamorro people (Russell 1998, p. 86). Sarigan consists of a low truncated volcanic cone with a 2,460-ft (750-m)-wide summit crater containing a small ash cone. Other notable physical features of Sarigan include irregular shorelines with steep cliffs created by old lava flows (Berger et al. 2005, p. 12). Sarigan has undergone complete eradication of feral ungulates, following the recommendation of the 1998 Fish and Wildlife Biological Opinion for U.S. Navy mitigation for their bombing activities on FDM. The ungulate removal project was a cooperative effort by FWS, U.S. Navy, CNMI Division of Fish and Wildlife (DFW), and the Northern Islands Mayor's Office. The islands' native vegetation and fauna is now increasing in species richness and population numbers (Kessler 2011, pp. 320-322). Ecosystem types on Sarigan include forest and savanna. Two of the 23 species are known to occur on Sarigan (Slevin's skink and the humped tree snail). We are unaware of historical occurrences of the other 21 species on Sarigan.

Guguan

Located approximately 19 mi (30 km) south of Alamagan and 40 mi (64 km) northeast of Sarigan, Guguan is an uninhabited island with volcanic activity, measuring 2 mi

(4 km

) and a peak elevation of 988 ft (301 m) (Ohba 1994, p. 16). The island is not believed to have been inhabited by the Chamorro people (Russell 1998, pp. 83-89). Its north side is devoid of vegetation resulting from volcanic activity, and its south side is a vegetated, eroded, volcanic cone. Other notable physical features of Guguan include steep cliffs along the shoreline and moist to wet ravines (SIO 2014, in litt.). Also notable is the presence of dense seabird colonies (Ohba 1994, p. 16; Berger et al. 2005, p. 12). Guguan supports the forest ecosystem. The entire island of Guguan is a designated conservation area (Berger et al. 2005, p. 15). One of the 23 species occurs on Guguan (Slevin's skink). The plant

Solanum guamense

occurred on Guguan historically.

Alamagan

Located approximately 18 mi (29 km) north of Guguan and 30 mi (48 km) south of Pagan, Alamagan is an uninhabited island with volcanic activity, measuring 4 mi

(11 km

), and a peak elevation of 2,441 ft (744 m) at Mt. Alamagan (Ohba 1994, p. 16). Alamagan is an emergent summit of a large stratovolcano (steep, many-layered volcano characterized by periodic explosive eruptions) with a 1,148-ft (350-m) deep summit crater at the center of the island (Berger et al. 2005, p. 12). Most of the historically recent eruptions have been violently explosive (Berger et al. 2005, p. 12). The island was inhabited by the Chamorro people (Russell 1998, p. 86). Alamagan supports the forest and savanna ecosystems. Two of the 23 species are known to occur on Alamagan (Slevin's skink and the humped tree snail). We are unaware of historical occurrences of the other 21 species on Alamagan.

Pagan

Located 42 mi (68 km) from Agrihan and 30 mi (48 km) from Alamagan, Pagan is the fifth largest island in the Marianas archipelago, and the largest of the northern Mariana Islands, with an area of 19 mi

(48 km

) (Ohba 1994, p. 17). Four volcanoes comprise Pagan: Mt. Pagan in the north, and an unnamed complex of three older volcanoes to the south (Ohba 1994, p. 17; Smithsonian Institution 2014a, in litt.). These volcanoes are connected by a narrow isthmus. The highest point on this island is Mt. Pagan, which rises 1,870 ft (570 m) above sea level. Mt. Pagan is one of the most active volcanoes in the Mariana Islands, with its most recent eruption in 2012 (Smithsonian Institution 2014b, in litt.). The largest eruption during historical times took place in 1981, when lava buried 10 percent of the island, and ash covered the entire island, forcing the 53 residents to flee to Saipan (Smithsonian Institution 2014b, in litt.). The island of Pagan supports the forest and savanna ecosystems. Three of the 23 species are known to occur on Pagan, the tree

Cycas micronesica

and the animals Slevin's skink and the humped tree snail. The plant

Bulbophyllum guamense

occurred historically on Pagan.

Agrihan

Located approximately 64 mi (102 km) south of Asuncion, and 39 mi (63 km) north of Pagan, Agrihan is an almost perfectly round, active volcanic cone (Ohba 1994, p. 17). None of the 23 species addressed in this proposed rule are known to have historically occurred, or to currently occur, on Agrihan, but other listed species, the Mariana fruit bat and the Micronesian megapode, occur there.

Asuncion

Asuncion is located approximately 23 mi (37 km) southeast of Maug and 62 mi (100 km) north of Agrihan. This island is an active, uninhabited volcano measuring 3 mi

(7 km

), with a peak elevation of 2,923 ft (891 m) (Ohba 1994, p. 18; Mueller-Dombois and Fosberg 1998, p. 245). Historically, Asuncion was inhabited by Chamorro peoples when Sanvitores arrived in the mid 1600s, and as evidenced by coconut groves (Mueller-Dombois and Fosberg 1998, p. 235). The long interval since Asuncion's last confirmed eruption in 1906 (Smithsonian Institution 2014c, in litt.), in conjunction with its high summit often enclosed by clouds (Ohba 1994, p. 18), affords this cone-shaped volcanic island densely forested slopes with diverse vegetation. Asuncion supports the forest and savanna ecosystems (Ohba 1994, p. 18). The entire island of Asuncion is a designated conservation area (Berger et al. 2005, p. 15). One of the 23 species addressed in this proposed rule is known to occur on Asuncion (Slevin's skink). The plant

Solanum guamense

occurred historically on Asuncion.

Maug

Located approximately 43 mi (70 km) south of Uracas and 24 mi (39 km) north of Asuncion, Maug consists of three small, uninhabited islets (East Island, West Island, and North Island). The three islets are the emergent portions of a largely submerged volcano, with a central lagoon within a sunken crater (Ohba 1994, p. 18; Mueller-Dombois and Fosberg 1998, p. 244). The collective land mass of the three islets measures 0.8 mi

(2 km

) with the highest elevation at 745 ft (227 m) at North Island (Ohba 1994, p. 18; Mueller-Dombois and Fosberg 1998, p. 244). Historically, Chamorro people inhabited Maug (Russell 1998, p. 88), and the islets were briefly inhabited by the Japanese during World War II (Russell

1998, pp. 96-97). Each of the three islets consists of narrow rocky ridges covered primarily by grasslands, sedges, and scrub; however, larger trees such as

Hernandia

sp.,

Pisonia grandis,

and

Terminalia catappa

have been reported to occur in ravines on the leeward sides (Ohba 1994, p. 18; Mueller-Dombois and Fosberg 1998, pp. 244-245). Ecosystems on Maug include forest and savanna, which currently provide habitat for large breeding colonies of a variety of seabirds (Ohba 1994, p. 18). All three islets that comprise Maug are designated as a conservation area (Berger et al. 2005, p. 15). None of the 23 species addressed in this proposed rule are known to currently occur on the islands of Maug. The plant

Solanum guamense

occurred historically on Maug.

Uracas

Uracas (Farallon de pajaros), is the northernmost island of the Mariana archipelago, roughly 43 mi (70 km) northwest of Maug. The island is an active, uninhabited volcano measuring 0.9 mi

(2 km

) and with a peak elevation of 1,180 ft (334 m) (Ohba 1994, p. 18). None of the 23 species addressed in this proposed rule, or any previously listed species, are known to have historically occurred, or to currently occur, on Uracas.

An Ecosystem-Based Approach to Assessing the Conservation Status of 23 Species in the Mariana Islands

In this document, we have analyzed the threats to each of the 23 Mariana Islands species individually to determine the appropriate status of each species on its own merits under the Act. However, because many of these species, and particularly those that share the same habitat types (henceforth referred to as ecosystems), share a very similar suite of threats, we have organized the 23 species addressed in this proposed rule by common ecosystem for efficiency, to reduce repetition for the reader, and to reduce publication costs. Therefore, we begin our analysis of the potential threats to each of the 23 species by first describing the relevant ecosystems in which these species occur, to avoid repeating the habitat characteristics associated with each individual species found in the same ecosystem. Organizing the rule in this way also allows us to describe threats that affect multiple species occurring in shared ecosystems in a more efficient manner, again reducing repetition for the reader and saving publication costs.

In addition, as an incidental benefit of assessing the threats to the 23 species using shared ecosystems as an organizational tool, we have laid the groundwork for better addressing threats to these species, should they be listed. On the Mariana Islands native species occurring in the same habitat types depend on many of the same physical and biological features and the successful functioning of their specific ecosystem to survive. Because these species that share ecosystems face a suite of shared threats, managing or eliminating these threats holistically at an ecosystem level is more cost effective and should lead to better resource protection for all native species. Cost-effective management of these threats requires implementation of conservation actions at the ecosystem level to enhance or restore critical ecological processes and provide for long-term viability of species and their habitat. Organizing the 23 Mariana Islands species by shared ecosystems sets the stage for a conservation management approach of protecting, restoring, and enhancing critical ecological processes at an ecosystem scale for the long-term viability of all associated native species in a given ecosystem type and locality, thus potentially preventing the future imperilment of any additional species that may require protection. This approach is in accord with the primary stated purpose of the Act (see section 2(b)): “to provide a means whereby the ecosystems upon which endangered species and threatened species depend may be conserved.”

Each of the 23 Mariana Islands species is found in one of the four ecosystem types described in this rule: forest, savanna, stream, and cave (Table 2). Of the 23 species, only the Pacific sheath-tailed bat is found in more than one ecosystem type (forest and cave).

Table 2—The 23 Mariana Islands Species and the Ecosystems Upon Which They Depend

Ecosystem

Species

Plants

Animals

Forest

Bulbophyllum guamense

Cycas micronesica

Dendrobium guamense

Eugenia bryanii

Heritiera longipetiolata

Maesa walkeri

Nervilia jacksoniae

Psychotria malaspinae

Solanum guamense

Tabernaemontana rotensis

Tinospora homosepala

Tuberolabium guamense

Pacific sheath-tailed bat.

Slevin's skink.

Mariana eight-spot butterfly.

Mariana wandering butterfly.

Humped tree snail.

Langford's tree snail.

Guam tree snail.

Fragile tree snail.

Savanna

Hedyotis megalantha

Phyllanthus saffordii

Stream

Rota blue damselfly.

Cave

Pacific sheath-tailed bat.

For all of the proposed species, we identified and evaluated those factors that are threats to each individual species specifically (species-specific threats), as well as those factors which are common threats to all of the species of a given ecosystem type (ecosystem-level threats). For example, the degradation of habitat by nonnative ungulates is considered a direct or indirect threat to 17 of the 23 species proposed for listing as endangered or threatened species. We have labeled such threats that are shared by all species within the same ecosystem as an “ecosystem-level threat,” because they impact all proposed species occurring in that ecosystem type in terms of the nature of the impact, its severity, timing, and scope. Beyond ecosystem-level threats, we further identified and evaluated species-specific threats that may be unique to certain species. For example, the threat of predation by nonnative flatworms is unique and specific to the four tree snails addressed in this rule.

Mariana Islands Ecosystems

For the purposes of organizing our threats discussion for the 23 species by shared habitats, we describe four broad Mariana Islands ecosystems: Forest,

savanna, stream, and cave, based on physical features, elevation, substratum, vegetation type, and hydrology (see

“The Mariana Islands,”

above). We acknowledge the presence of other ecosystems (e.g., coastal, wetland) in the Mariana Islands, however we limit our discussion to these four because they are the relevant ecosystems that support the 23 species proposed for listing as endangered or threatened species in this rule.

Forest Ecosystem

There are two substrate types in the forest ecosystem, limestone and volcanic (Stone 1970, pp. 9, 14, 18-24; Falanruw et al. 1989, pp. 6-9; Ohba 1994, pp. 19-29; Mueller-Dombois and Fosberg 1998, p. 243). The annual rainfall in the forest ecosystem lies within the archipelago average, ranging from 78 to 100 inches (in) (2,000 to 2,500 millimeters (mm)), with a rainy season from June or July through October or November. The temperature of the forest ecosystem mirrors the archipelago monthly averages, between 75 degrees Fahrenheit (°F) and 82 °F (24 degrees Celsius (°C) and 28 °C), with extremes of 64 °F and 95 °F (18 °C and 35 °C). Multiple plant species are present throughout the forest ecosystem, and on most of the islands; however, variations in species structure are observed (Fosberg 1960, pp. 37, 56-59, plates 1-40; Falanruw et al. 1989, pp. 6-9; Ohba 1994, pp. 19-29; Mueller-Dombois and Fosberg 1998, pp. 257, 268, 270-271).

Native canopy species in the forest ecosystem (as defined here) include but are not limited to:

Artocarpus mariannensis, Barringtonia asiatica,

Claoxylon

spp.,

Cordia subcordata, Cyathea

spp.,

Cyanometra ramiflora, Elaeocarpus joga,

Ficus prolixa, Guamia mariannensis,

Hernandia labyrinthica, H. sonora,

Maytenus thompsonii, Merrilliodendron megacarpum,

Ochrosia mariannensis, Pandanus dubius,

P. tectorius, Pisonia grandis,

Pouteria obovata,

and

Premna obtusifolia

(Falanruw et al. 1989, pp. 6-9; Raulerson and Rinehart 1991, pp. 6-7, 11, 14, 20, 24, 28, 33, 50, 52-53, 62-63, 72, 91, 96, 104; Ohba 1994, pp. 19-29; Mueller-Dombois and Fosberg 1998, pp. 257, 268, 270-271; Wiewel et al. 2009, pp. 206-207). Native subcanopy species include but are not limited to:

Aglaia mariannensis, Aidia cochinchinensis,

Allophyllus timoriensis, Cyathea aramaganensis,

Eugenia palumbis, E. reinwardtiana,

Hibiscus tiliaceus, Neisosperma oppositifolia,

Psychotria mariana,

and

Xylosma nelsonii

(Stone 1970, pp. 9, 14, 18-24; Falanruw et al. 1989, pp. 6-9; Raulerson and Rinehart 1991, pp. 13, 47, 56, 59, 68-69, 77, 84, 88; Ohba 1994, pp. 19-29; Mueller-Dombois and Fosberg 1998, pp. 252-253, 257, 268, 272); and native understory species include but are not limited to:

Discocalyx megacarpa, Hedyotis

spp.,

Nephrolepis bisserrata, N. hirsutula,

Phyllanthus marianus,

and

Piper guamense

(Falanruw et al. 1989, pp. 6-9; Ohba 1994, pp. 19-29; Mueller-Dombois and Fosberg 1998, pp. 247, 268). Further, in select areas of the forest ecosystem, usually where the forest is situated to receive and retain more moisture, the canopy trees are covered in various mosses and epiphytic ferns and orchids (Mueller-Dombois and Fosberg 1998, p. 268).

Dominant canopy, subcanopy, and understory species can vary from one location to the next on the same island, and from island to island. These species can be endemic to one island, occur on one or more of the southern islands (e.g., the understory species

Discocalyx megacarpa

), or occur on one or more of the northern islands (e.g.,

Cyathea aramaganensis

). In addition, biologists have observed overlap of forest species on limestone and volcanic substrata, suggesting that physical properties may be more important than chemical properties of these substrates in determining vegetation characteristics (Mueller-Dombois and Fosberg 1998, pp. 262-264). Elevation also contributes to variations in vegetation, as observed on Mt. Alutom, Mt. Almagosa, Mt. Lamlam, and Mt. Bolanus on Guam; the Rota Sabana; and on the slopes of the northern islands (Stone 1970, pp. 9, 14, 18-24; Falanruw 1989, pp. 4-6; Mueller-Dombois and Fosberg 1998, pp. 262-264); although in some cases there is no definite correlation with elevation (i.e., the moisture-retaining, moss-and-epiphyte-covered sections of the forest ecosystem are found near the coast in some areas and also at mid to high elevations) (Fosberg 1960, p. 30).

Additionally, biologists have observed a change in distribution of

Hernandia

species with elevation. For example,

H. sonora,

dominant on the coastal side of the forest ecosystem, changes distinctly to

H. labyrinthica

as the elevation increases (Amidon 2000, p. 49). The significance of these interpretations of forest-associated species in the Mariana archipelago to the 14 plants in this rule is not adequately definitive to subclassify a forest type for each of the species in this rule; therefore, we describe a general forest ecosystem here, with the substrate, temperatures, rainfall, and associated native canopy, subcanopy, and understory species, listed above. The forest ecosystem supports 21 of the 23 species proposed for listing as endangered or threatened species in this rule (all except the plants

Hedyotis megalantha

and

Phyllanthus saffordii,

which occur only in the savanna ecosystem).

Savanna Ecosystem

The savanna ecosystem of the Mariana Islands is characterized by volcanic substrate, primarily of basalts, with laterite soil (red clay rich in iron and aluminum) and a vegetation type in which grasses are the dominant plants. The savanna ecosystem on Guam is segmented by multiple narrow ravine forests, with some grassland (Mueller-Dombois and Fosberg 1998, pp. 241, 272). Savanna is considered a primary ecosystem type; however, human clearing and burning of forests and the presence of feral ungulates have contributed toward the expansion of secondary savanna into areas that previously supported the forest ecosystem (Mueller-Dombois and Fosberg 1998, pp. 241-243; Stone 1970, p. 31). Some authorities have suggested that savanna should not be classified as a native ecosystem in the Mariana Islands (Athens and Ward 2004, p. 27); however, we concur with Mueller-Dombois and Fosberg (1998, pp. 241-243), Stone (1970, pp. 14, 19, 21, 23, 30), and Hunter-Anderson (2009, 16 pp.), that savanna can be classified as a primary ecosystem type. Hunter-Anderson published a detailed analysis of charcoal samples, historical climate change trends, patterns of soil deposition, known agricultural techniques used by the early settlers, and Holocene-age pollen and spore studies, all indicating that the first settlers did not use fire to create or enlarge new open areas (savanna) for agriculture (Hunter-Anderson 2009, 16 pp.). These findings support the theory that the savanna ecosystem type existed prior to human presence in the Mariana Islands.

Annual rainfall in the savanna ecosystem ranges from 78 to 100 in (2,000 to 2,500 mm), with a rainy season from June or July through October or November. Likewise, the temperature of the savanna ecosystem averages between 75 °F and 82 °F (24 °C and 28 °C), with extremes of 64 °F and 95 °F (18 °C and 35 °C). Several endemic plant species are associated with the savanna ecosystem: the grass

Dimeria chloridiformis;

the small herbaceous perennial

Dianella saffordiana,

and the small tree

Phyllanthus mariannensis

(Stone 1970, pp. 19, 388, 549; Mueller-Dombois and Fosberg 1998, pp. 241-243; Hunter-Anderson 2009, 16 pp). Other native savanna species include

the shrubs

Decaspermum fruticosum, Dodonaea viscosa,

Melastoma marianum, Myrtella bennigseniana,

and

Wikstroemia elliptica,

the grass

Digitaria mariannensis;

and subspecies of the fern

Dicranopteris.

Another dominant but controversial component of the savanna ecosystem is the grass

Miscanthus floridulus

(giant miscanthus). Although

M. floridulus

occurred historically on Pagan as analyzed in fossil records studied in 1958 (Fosberg and Corwin 1958, pp. 8-9), and currently occurs on almost all of the 15 Mariana Islands, this species is considered invasive by most Mariana Islands ecologists. Recent field observations revealed that

M. floridulus

often grows in widespread, monotypic stands, whereas endemic plants such as

Hedyotis megalantha

and

Phyllanthus saffordii

grow compatibly within patches of the native fern

Dicranopteris linearis

(Gawel 2012, in litt.). The savanna ecosystem supports 2 of the 14 plant species proposed for listing as endangered or threatened species in this rule (

Hedyotis megalantha

and

Phyllanthus saffordii

Cave Ecosystem

The cave ecosystem is largely located in limestone (karst) areas on the southern islands of Saipan, Aguiguan, Rota, and Guam (Taborosi 2004, pp. 14-15). Limited areas of cave ecosystem also occur on the volcanic northern Mariana Islands where lava tubes and other crevices occur. The cave ecosystem includes stream caves, lava tubes, sea caves, and solution caves (Taborosi 2004, pp. 2, 11; Water and Environmental Research Institute and the Western Pacific-Island Research and Education Initiative (WERI-IREI) 2014, in litt.). Solution caves are the most common, except for on Tinian, which has mostly flank margin caves (Stafford et al. 2005, p. 20; WERI-IREI 2014, in litt.). Solution caves are cavities that have developed in the limestone substrate through the action of running water, erosion, and collapse (WERI-IREI 2014, in litt). Flank margin caves form at the distal margin of the fresh water lens, where mixing of fresh and saline waters occurs (Stafford et al. 2005, p. 20).

Ambient temperatures and rainfall in the cave ecosystem are the same as for surrounding areas in the Marianna Islands (average of 75 °F to 90 °F (24 °C to 32 °C); rainfall 78 in (2,000 mm) per year) (Wiles et al. 2009, p. 10 in O'Shea and Valdez 2009). Thermal characteristics of the interiors of caves show little variability, and relative humidity is high. Humidity measured in four caves on Aguiguan ranged from 92 to 96 percent (O'Shea and Valdez 2009, p. 78 in O'Shea and Valedez 2009). Internal cave temperatures (between caves) vary less than a few degrees, between 79 °F to 82 °F (26 °C to 28 °C), and temperatures within each cave are essentially constant (O'Shea and Valdez 2009, p. 77 in O'Shea and Valedez 2009). No major air movement was detected within caves to indicate any complex thermal patterns (O'Shea and Valdez 2009, p. 77 in O'Shea and Valedez 2009).

Cave sizes range from small (less than 49 ft (15 m) long and 538 ft

(50 m

)) in floor area, with low rock overhangs, narrow vertical crevices, various cavities at the base of cliffs or under large boulders; to medium (538 ft

to 1,076 ft

(50 to 100 m

) in floor area, with wider rooms; to large (over 1,076 ft

(100 m

)) in floor area, with ceiling heights reaching 16 to 98 ft (5 to 30 m)) (Wiles et al. 2009, p. 11 in O'Shea and Valdez 2009).

Cave ecosystems suitable for the Pacific sheath-tailed bat should be within or near mature native forest, to provide an attainable food source (Wiles et al. 2009, p. 10 in O'Shea and Valdez 2009; Gorresen et al. 2009, p. 44 in O'Shea and Valdez 2009). Pacific sheath-tailed bats prefer the larger caves, if available (Wiles et al. 2009, p. 15 in O'Shea and Valdez 2009), but may also be found in smaller caves, especially where there may be less disturbance (e.g., use by goats or humans).

One of the 23 species proposed for listing as endangered in this rule, the Pacific sheath-tailed bat, depends on the cave ecosystem for its life-history needs.

Stream Ecosystem

Streams can be a part of a wetland ecosystem; however, for this proposed rule, we discuss only the more narrowly defined stream ecosystem. Only one species addressed in this rule is found in the stream ecosystem, the Rota blue damselfly, which occurs only on Rota.

Only two of the Mariana Islands have permanent streams, Guam and Rota. Guam has 14 named watersheds with more than 100 streams and rivers (WERI-IREI 2014, in litt.). Saipan has a brackish-water lake, Lake Susupe. Intermittent headwaters originating from Mount Tagpochau and the Fina Sisu ridge during heavy rains provide water to the lake, but there are no permanent streams on Saipan (Wong and Hill 2000, p. 1). Currently on Tinian, there are no permanent streams, and only one functional wetland, Lake Hagoi (Stinson 1995, in litt.). The limestone substrate of these southern islands is very porous, and rain that falls is evaporated, consumed by plants, runs directly off the land surface into the ocean, or recharges ground water (Carruth 2003, p. 13). The northern islands are not known to have permanent streams; however, Pagan has a freshwater lake with hot sulfur springs, and a small brackish-water lake (Guam.net,

http://www.guam.net/pub/sshs/depart/science/mancuso/marianas/pagan/pagan.htm,

accessed April 30, 2014).

The western end of Rota is dominated by the “Sabana” region, which is an irregular plateau 1,300 ft (400 m) high, 2.5 mi by 1.6 mi (4 km by 2.5 km), with two prominent peaks nearly 1,600 ft (500 m) high. The Sabana area is very porous, with internal caves, and any ponding water after a rainfall event filters quickly into the substrate, leaving ephemeral streams (Keel et al. 2007, pp. 12-16). The east, north and west of the plateau gradually drops off in a series of terraces. The south side of the plateau has steep cliffs in the Talakhaya area, with springs and the only surface streams on the island (Keel et al. 2007, p. 3). The stream ecosystem on Rota encompasses these streams and springs in the Talakhaya area, and is the only known location of the Rota blue damselfly (as described in “

Animals

—Rota Blue Damselfly,” below).

On Rota, there is a distinct rainy season from July through December, with an average annual rainfall of 102 in (2600 mm). Ambient temperature averages 81 °F (27 °C) (see “Islands in the Mariana Archipelago,” above). The rainy season and rainfall amounts can dramatically change (become drier) due to the El Niño-Southern Oscillation (ENSO) which also affects stream levels (Keel et al. 2007, p. 6).

The vegetation along the streams consists primarily of mature, tall-canopied, native limestone forest (Keel et al. 2007, p.10; U.S. Forest Service 2014, in litt.). The vegetation type and components are further described in Forest Ecosystem, above.

The Talakhaya Springs within the Sabana Watershed are used as a primary domestic water source. The springs consist of Water Cave (also known as Matan Hanum Spring) and As Onon Spring. The municipal water is obtained by gravity flow from these two springs (up to 1.8 million gallons a day (2.8 cubic feet per second)) (Keel et al. 2007, pp. 1, 5; Stafford et al. 2002, p. 17). Under ordinary climatic conditions, this area supplies water in excess of demand but ENSO-induced drought conditions can lead to significantly reduced discharge, or may completely dewater the streams (Keel et al. 2007, pp. 3, 6, 19). In 1998, water captured from the

springs was inadequate for municipal use, and water rationing was instituted (Keel et al. 2007, p. 6). As the annual temperature rises resulting from global climate change, other weather regime changes such as increases in droughts, floods, and typhoons will occur (Giambelluca et al. 1991, p. iii). Increasing night temperatures cause a change in mean precipitation, with increased occurrences of drought cycles (Loope and Giambelluca 1998, pp. 514-515; Emanuel et al. 2008, p. 365; U.S. Global Change Research Program (US-GCRP) 2009, pp. 145-149, 153; Keener et al

2010, pp. 25-28; Finucane et al

2012, pp. 23-26; Keener

et al

2012, pp. 47−51).

The limestone substrate of Rota is porous, with filtration through central Sabana being the sole water source for the few streams on the island and for human use. There are no other ground water supplies on the island, and limited storage capacity. The Rota blue damselfly is dependent upon any water that escapes the Talakhaya Springs naturally, what is not already removed for human use. The likelihood of dewatering of the Talakhaya Springs is high due to climate change causing increased ENSO conditions, and increased human demand. The “Public and Agency Participation” section of the Comprehensive Wildlife Conservation Strategy for the Commonwealth of the Northern Mariana Islands (2005, p. 347) cites “individuals state the the Department of Public Works has been increasing their water extraction from Rota's spring/stream systems. Historically, this water source flowed year-around, yet now they are essentially dry most of each year.” See the species description in “Rota blue damselfly,” below, and the “Water Extraction” section under

Factor E. Other Natural or Manmade Factors Affecting Their Continued Existence,

below, for further discussion.

Description of the 23 Mariana Islands Species

Plants

In order to avoid confusion regarding the number of populations of each species (i.e., because we do not consider an individual plant to represent a viable population), we use the word “occurrence” instead of “population.” Additionally, we use the word occurrence to refer only to wild (i.e., not propagated and outplanted) individuals because of the uncertainty of the persistence to at least the second generation (F2) of the outplanted individuals. A population consists of mature, reproducing individuals forming populations that are self-sustaining. Also, there is a high potential that one or more of the outplanted populations may be eliminated by normal or random adverse events such as fire, nonnative plant invasion, or disease, before a seed bank can be established.

Bulbophyllum guamense

(cebello halumtano), an epiphyte in the orchid family (Orchidaceae), is known from widely distributed occurrences on the southern Mariana Islands of Guam and Rota, in the forest ecosystem (Ames 1914, p. 13; Raulerson and Rinehart 1992, p. 90; Costion and Lorence 2012, pp. 54, 66; Global Biodiversity Information Facility (GBIF) 2012a-

Online Herbarium Database

Bulbophyllum guamense

was recorded historically on Guam from clifflines encircling the island, and on the slopes of Mt. Lamlam and Mt. Almagosa. As recently as 1992, this species was reported to occur in large mat-like formations on trees “all over the island,” (Guam) (Raulerson and Rinehart 1992, p. 90). Currently, numbers have declined dramatically, and there are only 4 known occurrences (3 on Guam and 1 on Rota) totaling fewer than 250 individuals on Guam and fewer than 30 individuals on Rota. Historically, this species also occurred on Pagan (last observed in 1984) and Saipan (last observed in 1970).

Bulbophyllym guamense

has thus been lost from two of the four islands where it formerly occurred, and only a few small populations of the species remain on Guam and Rota. The remaining individuals of

B. guamense

are vulnerable to the effects of continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, fires, and typhoons, combined with predation by nonnative invertebrates such as slugs.

Cycas micronesica

(fadang), a cycad in the cycad family (Cycadaceae), is known from Guam, Rota, and Pagan, as well as Palau (politically the independent Republic of Palau) and Yap (geographically part of the Caroline Islands; politically part of the Federated States of Micronesia), in the forest ecosystem (Hill et al. 2004, p. 280; Keppel et al. 2008, p. 1,006; Cibrian-Jaramillo et al. 2010, pp. 2,372-2,375; Marler 2013, in litt.).

Just 10 years ago,

Cycas micronesica

was ubiquitous on the island of Guam, and similarly common on Rota.

Cycas micronesica

is currently under attack by a nonnative insect, the cycad aulacaspis scale (

Aulacaspis yasumatsui

) that is causing rapid mortality of plants at all locations (Marler 2014, in litt.). As of January 2013,

C. micronesica

mortality reached 92 percent on Guam, and cycads on Rota are experiencing a similar fate (Marler 2013, in litt.). All seedlings of

C. micronesica

in a study area were observed to die within 9 months of infestation by

C. yasumatsui

(see

Factor C. Disease and Predation,

below for further discussion) (Marler and Muniappan 2006, p. 3; Marler and Lawrence 2012, p. 233; Marler 2013, pers. comm.; Western Pacific Tropical Research Center 2012, p. 4).

Currently, there are 15 to 20 occurrences of

Cycas micronesica

totaling 900,000 to 950,000 individuals on the Micronesian Islands of Guam, Rota, Pagan, Yap, and Palau. On Guam and Rota there are fewer than 630,000 (Marler 2013, pers. comm.). These totals do not distinguish between successfully reproducing adults and juveniles (Marler 2013, pers. comm.), which, because of the effects of the cycad aulacaspis scale, implies that the number of extant individuals that can successfully reproduce is much lower. On Guam, there are four fragmented occurrences, totaling fewer than 516,000 individuals: one occurrence along the shoreline to the base of the limestone cliffs on the north side; a second occurrence beginning at the forest edge along the cliffs and continuing into the forest on the north side; a third occurrence on the northern plateau; and a fourth occurrence along the ravines and rock outcrops on the southern side, with a few individuals occurring across the savanna.

On Rota, there are four known occurrences within the forest ecosystem, totaling fewer than 111,500 individuals (Marler 2013, in litt.). On the northeast shore the first occurrence totals fewer than 25,500 individuals; the second occurrence, on the northwest shore, totals fewer than 21,600 individuals; the third occurrence on the south shore totals fewer than 63,600 individuals; and the fourth occurrence on Wedding Cake peninsula totals fewer than 300 individuals.

There are likely a relatively limited number of individuals of

Cycas micronesica

on Pagan. In recent surveys, Pratt (2011, pp. 33-42) reported finding representatives of the species in a ravine on the southwestern part of the island.

Yap consists of a group of four islands, three of which are separated by water but share a common reef, with a total land area of 39 mi

(102 km

). On Yap, there are three occurrences of

Cycas micronesica

totaling 288,450 individuals (Marler 2013, in litt). Palau consists of three larger islands, Babeldaob, Koror, and Ngeruktabel, and between 250 and 300 smaller islands referred to as the “Rock Islands.” The

total land area is 177 mi

(458 km

). On Palau, four occurrences of

C. micronesica

total fewer than 2,500 individuals: (1) two occurrences on Ngeruktabel Island total fewer than 900 individuals, (2) one occurrence on Ngesomel Island totals fewer than 600 individuals, and (3) possibly as many as 1,000 individuals scattered on the Rock Islands (Marler 2013, in litt.). The aulacaspis scale was observed on the main islands of Palau in 2008 (Marler 2014, in litt.), and is expected to reach Yap as well (Marler 2013, in litt.).

Protecting and preserving

Cycas micronesica

on the islands of Guam and Rota is important, as it is an integral component of the forest ecosystem, and over 50 percent of the known individuals occur on these islands. The nonnative cycad aulacaspis scale quickly causes mortality of all life stages of

C. micronesica,

preventing reproduction of

C. micronesica,

and leading to its extirpation (see

Factor C. Disease and Predation,

below). The magnitude of the ongoing threats of predation by the scale and nonnative animals, secondary infestations by other insects, and loss of habitat due to development, typhoons, climate change, and direct damage and destruction by military live-fire training is large, and these threats are imminent. Although

C. micronesica

presently is found in relatively high numbers, the factors affecting this species can result in very rapid mortality of large numbers of individuals. A study by Marler and Lawrence (2012) shows that if the ongoing negative population density trajectory for

C. micronesica

established over 4 years is sustained, extirpation of

C. micronesica

from Guam and Rota will occur by 2019.

Dendrobium guamense

(no common name (NCN)), an ephiphyte in the orchid family (Orchidaceae), is known from Guam, Rota, and Tinian, in the forest ecosystem (Ames 1914, p. 14; Raulerson and Rinehart 1992, p. 98; Costion and Lorence 2012, p. 66). As recently as the 1980s, this species was common in trees on Guam and Rota, with more than 12 occurrences on Guam and 17 occurrences on Rota (Bishop Museum 2013—

Online Herbarium Database;

Consortium Pacific Herbarium (CPH) 2012a—

Online Herbarium Database,

5 pp.). Currently, there are 9 occurrences totaling approximately 550 individuals distributed among these islands. On Guam, there are 4 occurrences totaling fewer than 250 individuals (Harrington et al. 2012, in litt). On Rota, there are 4 occurrences of

D. guamense,

totaling fewer than 300 individuals (Harrington et al. 2012, in litt). There is one reported occurrence on the island of Tinian, with an unknown number of individuals (Quinata et al. 1994, p. 8; CPH 2012a—

Online Herbarium Database,

5 pp.). Historically,

D. guamense

was also known from Saipan, in the forest ecosystem (CPH 2012a—

Online Herbarium Database,

5 pp.). Formerly relatively common, the remaining populations of

D. guamense

and habitat for its reintroduction to Saipan are at risk;

D. guamense

populations are decreasing on Guam, Rota, and Tinian, and both the species and its habitat continues to be negatively affected by continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, fires, and typhoons, combined with predation by nonnative invertebrates such as slugs.

Eugenia bryanii

(NCN), a perennial shrub in the Myrtle family (Myrtaceae), is known only from Guam. Historically,

E. bryanii

occurred on windy, exposed clifflines along the west and east coasts of the island, and from along the Pigua River, in the forest ecosystem (Costion and Lorence 2012, p. 82; Gutierrez 2012, in litt.). Currently,

E. bryanii

is known from 5 occurrences totaling fewer than 420 individuals (Gutierrez 2014, in litt.). Populations of

E. bryanii,

a single island endemic, are decreasing from initial numbers observed on Guam, and these remaining small populations are at risk, due to continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, and typhoons, combined with herbivory by deer.

Hedyotis megalantha

(paudedo), a perennial herb in the coffee family (Rubiaceae), is known only from the savanna ecosystem on Guam. Historically,

H. megalantha

was reported solely from Guam; however, because several herbarium records reported this species on Rota and Saipan, we investigated other reports and taxonomic and genetic analyses concerning the range of this species. We believe the Rota and Saipan reports are misidentifications of one or more of the other

Hedyotis

species also found in the Mariana Islands (Fosberg et al. 1993, pp. 63-79; CPH 2012b—

Online Herbarium Database;

World Checklist of Select Plant Families (WCSP) 2012a—

Online Herbarium Database

). Between 1911 and 1966, this species ranged from the mid-central mountains and west coast of Guam, south to Mt. Lamlam (Bishop Museum 2013-

Online Herbarium Database

). Currently,

H. megalantha

is known from one large scattered occurrence totaling fewer than 1,000 individuals on southern Guam (Costion and Lorence 2012, pp. 54, 86; Gutierrez 2012, in litt.; Bishop Museum 2013—herbarium database; Gutierrez 2013, in litt.).

Hedyotis megalantha

typically occurs as lone individuals rather than in patches or groups (Gutierrez 2013, in litt.). In sum, the single known occurrence of

H. megalantha,

a single island endemic, is decreasing from initial numbers observed on Guam, and the remaining individuals are at continued risk due to ongoing habitat loss and destruction from agriculture, urban development, nonnative animals and plants, fires, and typhoons, combined with habitat destruction and direct damage by recreational vehicles.

Heritiera longipetiolata

(ufa-halomtano; looking glass tree), a tree in the hibiscus family (Malvaceae), is known only from the Mariana Islands. A few herbarium records have cited

H. longipetiolata

on Palau, Chuuk, Pohnpei, and the Eastern Caroline Islands; however, upon a thorough review of the literature and herbarium records, and conferring with local botanical experts, we conclude that these few outlying occurrences are actually

H. littoralis,

not

H. longipetiolata

(Stone 1970, pp. 23, 420-421; Raulerson and Rinehart 1991, p. 94; Wiles 2012, in litt.; Center for Plant Conservation 2010, in litt.; CPH 2012c—

Online Herbarium Database;

GBIF 2014—

Online Herbarium Database;

Harrington et al. 2012, in litt.; Lorence 2013, in litt.).

Historically,

Heritiera longipetiolata

is reported from Guam, Rota, Saipan, and Tinian, in the forest ecosystem (Stone 1970, p. 420; Raulerson and Rinehart 1991, p. 94; CPH 2012c—

Online Herbarium Database;

GBIF 2014—

Online Herbarium Database

). By 1997, there were about 1,000 individuals on Guam, several hundred on Tinian, and fewer than 100 on Saipan, with none observed on Rota (Wiles in Internation Union for Conservation of Nature (IUCN) Red List 2014, in litt.). Currently,

H. longipetiolata

is known from 9 occurrences totaling fewer than 160 individuals, on Guam, Saipan, and Tinian, all within the forest ecosystem (M and E Pacific, Inc., pp. 6, 8, 31, 78; Harrington et al. 2012, in litt; Grimm 2013, in litt). On Tinian,

H. longipetiolata

is known from fewer than 10 individuals (Williams 2013, in litt.). On Saipan,

H. longipetiolata

is known from 3 occurrences, totaling fewer than 30 individuals. Wiles stated that there is strong evidence that

H. longipetiolata

is not regenerating, and that seedlings and seeds are eaten by ungulates and crabs (Wiles in IUCN Red List 2014, in litt.).

Heritiera longipetiolata

is on Guam's endangered species list, listed as Vulnerable on IUCN's Red List of

Threatened Species, and is also a species of concern for Guam's Plant Extinction Prevention Program. The remaining populations of

H. longipetiolata

persist only in small numbers, and are decreasing from initial numbers observed on Guam, Saipan, and Tinian. With fewer than 200 individuals remaining across three islands, the species

Heritiera longipetiolata

and habitat for the recovery of the species on Rota are at risk due to ongoing habitat loss and destruction from agriculture, urban development, nonnative animals and plants, and typhoons. Herbivory by pigs and deer, and habitat and direct destruction by military live-fire training also contribute to the decline of

H. longipetiolata.

Maesa walkeri

(NCN), a shrub or small tree in the primrose family (Primulaceae), is found only in the Mariana Islands. Historically,

M. walkeri

is known from the islands of Guam and Rota, within the forest ecosystem (Fosberg and Sachet 1979, pp. 368-369; Raulerson and Rinehart 1991, p. 67; M and E Pacific, Inc. 1998, pp. 31, 79; Costion and Lorence 2012, p. 84; CPH 2012d—

Online Herbarium Database;

GBIF 2012b—

Online Herbarium Database;

Wagner et al. 2012—

Flora of Micronesia

). Several voucher specimens (preserved and labeled representative whole plants or plant parts, used to compare and correctly identify plant species, usually kept as part of an herbarium collection) report

M. walkeri

from the Carolinian Island of Pohnpei, but after careful review of the best available data (cited above) we conclude that

M. walkeri

is endemic to the Mariana Islands. Historically,

M. walkeri

was known from at least 13 occurrences on Guam and 9 occurrences on Rota (Bishop Museum 2014—

Online Herbarium Database

). Currently,

M. walkeri

is known from 4 occurrences in the forest ecosystem on Guam and Rota, totaling fewer than 60 individuals. On Guam, there are two individuals (M and E Pacific, Inc. 1998, pp. 31, 79; Grimm 2013, in litt.). On Rota,

M. walkeri

is known from 2 occurrences totaling approximately 50 individuals (Harrington et al. 2012, in litt.; Gawel 2013, in litt.).

Maesa walkeri

is also a species of concern for Guam's Plant Extinction Prevention Program.

In summary, the species

Maesa walkeri

is vulnerable to extinction due to its very limited numbers, totaling fewer than 60 individuals (with only 2 on Guam). The remaining populations of

M. walkeri

are decreasing from initial numbers observed on Guam and Rota, and continue to be affected by ongoing habitat loss and destruction from agriculture, urban development, nonnative animals and plants, fires, and typhoons. The impacts on the species are exacerbated by the effects of low numbers of individuals resulting in loss of vigor and genetic representation, which limits its ability to compete with other species and adapt to changes in environmental conditions.

Nervilia jacksoniae

(NCN), a small herb in the orchid family (Orchidaceae), is found only in the Mariana Islands. Historically,

N. jacksoniae

occurred on the islands of Guam and Rota, in the forest ecosystem, and ranged from northern to central Guam and only the southwestern point of Rota (Rinehart and Fosberg 1991, pp. 81-85; Raulerson and Rinehart 1992, p. 118; Costion and Lorence 2012, p. 67). Currently, there are approximately 15 occurrences totaling at least 520 individuals on the islands of Guam and Rota, in the forest ecosystem (Harrington et al. 2012, in litt.). On Guam,

N. jacksoniae

is known from 2 occurrences totaling fewer than 200 individuals (M and E Pacific, Inc. 1998, p. 58; Grimm 2012, in litt.; McConnell 2012, pers. comm.). On Rota,

N. jacksoniae

is known from 13 scattered occurrences totaling at least 320 individuals in the forest ecosystem (Rinehart and Fosberg 1991, pp. 81-85; Raulerson and Rinehart 1992, p. 118; Costion and Lorence 2012, p. 67; CPH 2012e—

Online Herbarium Database;

GBIF 2012c—

Online Herbarium Database;

McConnell 2012, pers. comm.). Populations of

N. jacksoniae

are decreasing from initial numbers observed on Guam and Rota and are at risk of further losses due to continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, fires, and typhoons, combined with predation by nonnative invertebrates such as slugs.

Phyllanthus saffordii

(NCN), a woody shrub in the Phyllanthaceae family, is historically known only from the southern part of Guam within the savanna ecosystem. Several literature and database sources report this species from the northern Mariana Islands (Costion and Lorence 2012, pp. 82-83; Wagner 2012—

Flora of Micronesia;

U.S. Department of Agriculture-Agricultural Research Service-Germplasm Resources Information Network (USDA-ARS-GRIN) 2013—

Online Database;

WCSP 2012b—

Online Database

); however, a thorough review of the literature, databases, and herbaria records revealed recorded occurrences only on Guam (Merrill 1914, pp. 104-105; Glassman 1948, p. 181; Stone 1970, pp. 387-388; Pratt 2011, p. 59; Gutierrez 2012, in litt.; GBIF 2012d—

Online Herbarium Database;

Bishop Museum 2013—

Online Herbarium Database;

Smithsonian Institution 2014-

Flora of Micronesia Database

). Until the early 1980s,

P. saffordii

ranged from central to southern Guam (Bishop Museum 2014—

Herbarium Database

). Currently,

P. saffordii

is known from 4 scattered occurrences on southern Guam, totaling fewer than 1,400 individuals (Gutierrez 2013, in litt.; Gawel et al. 2013, in litt.). In summary, populations of

P. saffordii,

a single island endemic, are decreasing from initial numbers observed on Guam and are at risk, due to continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, fires, and typhoons, combined with habitat destruction and direct damage by recreational vehicles.

Psychotria malaspinae

(aplokhating-palaoan), a shrub or small tree in the coffee family (Rubiaceae), is known only from Guam. Historically,

P. malaspinae

was known from scattered occurrences on the northeastern and southwestern sides of Guam, in the forest ecosystem (Merrill 1914, pp. 148-149; Stone 1970, pp. 554-555; Raulerson and Rinehart 1991, p. 83; Fosberg et al. 1993, pp. 111-112; Costion and Lorence 2012, pp. 54, 85-86; Bishop Museum 2014—

Online Database;

Wagner 2012—

Flora of Micronesia;

WCSP 2012c—

Online Database

). Currently,

P. malaspinae

is known from only three occurrences, each of a single individual (M and E Pacific, Inc. 1998, pp. 67, 79). None of these individuals has been observed within the last 5 years. Biologists searched for this species during rare plant surveys conducted in July 2012; however, none were located (Harrington et al. 2012, in litt.). A specimen collected from the Ritidian National Wildlife Refuge on Guam in August 2013 is currently pending identification (Gawel et al. 2013, in litt.).

Psychotria malaspinae

is also a species of concern for Guam's Plant Extinction Prevention Program.

The species

Psychotria malaspinae,

a single island endemic, has been reduced to three known individuals in the wild, rendering this species vulnerable to extinction. These remaining individuals are at risk, due to continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, and typhoons. Herbivory by pigs and deer, combined with the effects of low numbers of individuals, which results in loss of vigor and genetic representation, and limits its ability to compete with other species and adapt to changes in environmental conditions, contribute to the decline of

P. malaspinae.

Solanum guamense

(berenghenas halomtano), a small shrub in the

nightshade family (Solanaceae), is known only from the Mariana Islands (Merrill 1914, pp. 139-140; Stone 1970, p. 521; Costion and Lorence 2012, p. 89). Historically,

S. guamense

was reported from Guam, Rota, Saipan, Tinian, Asuncion, Guguan, and Maug (Stone 1970, p. 521; GBIF 2012e—

Online Database;

Bishop Museum 2014—

Online Database

). Currently,

S. guamense

is known from a single occurrence of one individual on Guam, in the forest ecosystem (Perlman and Wood 1994, pp. 135-136).

Once ranging across multiple islands,

Solanum guamense

is now vulnerable to extinction, the species having been reduced to a single remaining individual on Guam. This species, and habitat for its reintroduction to Rota, Saipan, Tinian, Asuncion, Guguan, and Maug, are at risk, due to continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, and typhoons. Herbivory by pigs and deer, combined with the effects of low numbers of individuals, which results in loss of vigor and genetic representation and limits its ability to compete with other species and adapt to changes in environmental conditions, contribute to the decline of

S. guamense.

Tabernaemontana rotensis

(NCN), a small to medium-sized tree in the dogbane family (Apocynaceae), is historically known from Guam and Rota, in the forest ecosystem (University of Guam (UOG) 2007, p. 6). The genus is widespread throughout tropical and subtropical regions. In 2004 (69 FR 1560, January 9, 2004), we proposed to list

T. rotensis;

however, in April 2004 (69 FR 18499) we did not list

T. rotensis

because an authoritative monographic work on the genus submerged this species in an expansive interpretation of the widespread species

T. pandacaqui.

In 2011, a genetic study was conducted on specimens from Rota, Guam, Asia, and the Pacific, to determine if those individuals on the Mariana Islands are a monophyletic lineage. The study determined that

T. rotensis

is a valid species, distinct from the widespread

T. pandacaqui

(Reynaud 2012, 27 pp. + appendices). In 2004,

T. rotensis

was known from 8 individuals on Rota, and at least 250 individuals on Guam. In 2007, more than 21,000 individuals were found throughout Andersen AFB, with a population structure representing seedlings, juveniles, and reproductive, mature individuals (UOG 2007 p. 4). Currently, on Rota,

T. rotensis

is known from two occurrences, each composed of fewer than five individuals (Harrington et al. 2012, in litt.). On Guam,

T. rotensis

is known from 6 occurrences totaling approximately 21,000 individuals (M and E Pacific, Inc. 1998, p. 61; UOG 2007, pp. 32-42).

In summary, populations of

Tabernaemontana rotensis

on Guam and Rota are at risk, due to continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, fires, and typhoons, combined with vandalism. The greatest concern regarding this species is not of population structure, but the small proximity of occurrences in an area that may be developed according to the proposed AFB and Navy base expansions (UOG 2007, p. 5; JGPO-NavFac Pacific 2010a, 2010b; JGPO-NavFac Pacific 2014).

Tinospora homosepala

(NCN), a vine in the moonseed family (Menispermaceae), is historically known only from Guam (Merrill 1914, p. 83; Stone 1970, pp. 27, 277; Costion and Lorence 2012, pp. 92-93). Currently,

T. homosepala

is known from 3 occurrences totaling approximately 30 individuals, in the forest ecosystem (Yoshioka 2008, p. 15; Gawel et al. 2013, in litt.). There is discussion among botanists as to whether or not

T. homosepala

is either the same as a commonly occurring species found throughout Malaysia and the Philippines or a variety of that species (

T. glabra

) (Costion and Lorence 2012, pp. 92-93; Gawel et al. 2013, in litt.).

Tinospora homosepala

differs from

T. glabra

in having equal-sized sepals (petal-like structures of the calyx) as opposed to the outer sepals being much smaller than inner sepals as in

T. glabra

(Costion and Lorence 2012, p. 93; Forman 1981, pp. 381, 417, and 419).

While these discussions note that additional research on the taxonomy of

Tinospora homosepala

is appropriate to address questions, no changes to the currently accepted taxonomy have been proposed, although Forman (1981, p. 419) notes that, if fruits of

T. homosepala

are discovered and are indistinguishable from

T. glabra,

it may be preferable to reduce

T. homosepala

to subspecific rank under

T. glabra.

Regardless, any future reduction in rank from full species status to that of a subspecies or variety would not, in itself, disqualify this taxon from protection under the Act. All known individuals of

T. homosepala

on Guam are said to be males that reproduce clonally (Yoshioka 2008, p. 15; Gawel et al. 2013, in litt.). Clonal reproduction limits genetic diversity, reducing the ability of the species to form new genetic combinations to fit changing environmental conditions (Stebbins 1957, p. 352). In summary, the species

T. homosepala,

a single island endemic, has been reduced to roughly 30 individuals on Guam, and it is possible that no female representatives of this species remain. These few remaining individuals of the species are at risk of extinction, due to continued habitat loss and destruction from nonnative animals and plants, and typhoons, and by genetic limitations as a result of the possible loss of potential sexual reproduction.

Tuberolabium guamense

(NCN) (

Trachoma guamense

is a synonym), an epiphyte in the orchid family (Orchidaceae), is known only from the Mariana Islands. Historically,

T. guamense

was reported from the islands of Guam, Rota, Tinian, and Aguiguan (Raulerson and Rinehart 1992, p. 127; CPH 2012f—

Online Herbarium Database;

GBIF 2012f—

Online Database

). The Royal Botanical Gardens at Kew's online database (WCSP 2012d—

Online Database

) describes the range for

T. guamense

as the Mariana Islands and the Cook Islands; however, we were unable to confirm this with herbarium specimens citing the Cook Islands as a site for collection (CPH 2012f—

Online Herbarium Database;

GBIF 2012f—

Online Herbarium Database;

Smithsonian Institution 2014-

Online Herbarium Database

). In 1992,

T. guamense

was found in “trees and shrubs all over the island” (Raulerson and Rinehart 1992, p. 127), and the Consortium of Pacific Herbaria has records of 22 collections from Guam, 5 collections from Rota, 15 collections from Tinian, and 3 collections from Aguiguan (CPH 2012f-

Online Herbarium Database

). Currently,

T. guamense

is known from three occurrences: one occurrence of one individual on Guam and two occurrences on Rota, in the forest ecosystem (Gawel et al. 2013, in litt.; Harrington et al. 2012, in litt.).

In summary, populations of

Tuberolabium guamense

are decreasing from initial numbers observed on Guam and Rota, and habitat for its reintroduction to Tinian and Aguiguan is at risk. The remaining few representatives of this species and its habitat are vulnerable to ongoing threats posed by the continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, fires, and typhoons. Herbivory by slugs, combined with the effects of low numbers of individuals which results in loss of vigor and genetic representation, and limits its ability to compete with other species and adapt to changes in environmental conditions, contribute to the decline of

T. guamense.

Animals

Pacific Sheath-Tailed Bat

The Pacific sheath-tailed bat (

Emballonura semicaudata rotensis

) is a small insectivorous bat (forearm length about 1.8 in (45 mm), weight 0.2 ounces (oz) (5.5 grams (g)), in the family

Emballonuridae,

an Old World bat family that has an extensive distribution primarily in the tropics (Lemke 1986, pp. 743-745; Nowak 1994, pp. 90-91; Lemke 1986, pp. 743-744; Koopman 1997, pp. 358-359; Wiles and Worthington 2002, pp. 1-3; O'Shea and Valdez 2009, pp. 9-10). The Pacific sheath-tailed bat is a rich brown to dark brown above and paler below (Walker and Paradiso 1983, p. 211). The common name “sheath-tailed bat” refers to the nature of the tail attachment: the tail pierces the tail membrane and its tip appears completely free on the upper surface of the membrane (Walker and Paradiso 1983, p. 209).

The Pacific sheath-tailed bat was once common and widespread in Polynesia and Micronesia, and is the only insectivorous bat recorded from a large part of this area (Hutson et al. 2001, p. 138). The classification of the subspecies has received varied treatment, but the most thorough and recent taxonomic evaluation for this subspecies was conducted by Koopman (1997, pp. 358-360). Koopman recognizes four subspecies:

E. s. rotensis,

endemic to the Mariana Islands (Guam and the CNMI);

E. s. sulcata,

occurring in Chuuk and Pohnpei;

E. s. palauensis,

found in Palau; and

E. s. semicaudata,

occurring in American and Independent Samoa, Tonga, Fiji, and Vanuatu. Historically, in the Mariana Islands, the Pacific sheath-tailed bat was known from Guam, Rota, Aguiguan, Tinian, Saipan, and possibly Anatahan and Maug (Lemke 1986, pp. 743-745; Steadman 1999, p. 321; Wiles and Worthington 2002, pp. 1-3). Currently, the Pacific sheath-tailed bat appears to be extirpated from all but one island in the Mariana Islands, Aguiguan, where a single remaining population of this subspecies is estimated to number between 359 to 466 individuals (Wiles and Worthington 2002, p. 15; Wiles 2007, pers. comm.; O'Shea and Valdez 2009, pp. 2-3).

The biology of this subspecies, including reproduction, habitat use, and diet, was, until recently, largely unknown (Wiles and Worthington 2002, p. 19; Esselstyn et al. 2004, p. 304). A study by O'Shea and Valdez (2009, pp. 95-97) reveals more life-history information. Fecal pellets of the Pacific sheath-tailed bat collected from two caves on Aguiguan show these bats consume a diverse array of prey, mostly consisting of small-sized insects including hymenopterans (ants, wasps, and bees), lepidopterans (moths), and coleopterans (beetles) as the three major food items (O'Shea and Valdez 2009, pp. 63-65).

The Pacific sheath-tailed bat appears to be cave-dependent, roosting during the day in a wide range of cave-types, including overhanging cliffs, karst limestone caves, crevices, and lava tubes (Grant et al. 1994, pp. 134-135; O'Shea and Valdez 2009, pp. 105-108). Bats and cave swiftlets (birds,

Aerodramus

spp.) may be found sharing caves (Lemke 1986, pp. 744-745; Tarburton 2002, pp. 106-107; Wiles and Worthington 2002, pp. 7, 13; Lemke 1986, pp. 744-745). Analysis of data collected from echolocation stations deployed across Aguiguan indicates that the bats' peak activity and occurrences are related to canopy cover, vegetation structure, and distance to known roosts; and that native limestone forest is preferred foraging habitat (O'Shea and Valdez 2009, pp. 105-108).

A previous survey of habitat use on Aguiguan in 2003 revealed that bats foraged almost entirely in forests (native and nonnative) near their roosting caves and clearly did not utilize the non-forested habitats on the island (Esselstyn et al. 2004, p. 307). Bruner and Pratt (1979, p. 3) also observed sheath-tailed bats foraging in native forests on Pohnpei. Large roosting colonies appear to be common for the Palau subspecies, but smaller aggregations may be more typical of at least the Mariana Island subspecies and perhaps other

Emballonura

found elsewhere (Wiles et al. 1997, pp. 221-222; Wiles and Worthington 2002, pp. 15, 17). In 1995, roosting bats on Aguiguan were detected in only 5 of 77 caves surveyed (Wiles 2007, pers. comm.), with colony sizes ranging from 2 to 64 individuals. Observations in 2007 indicated that the bats preferred large caves (over 1,076 ft

(100 m

)) in floor area, with ceiling heights reaching 16 to 98 ft (5 to 30 m)) (see “Cave Ecosystem,” above, for further cave description), as nearly all of the caves used for roosting were characterized as large by researchers (GDAWR 1995, pp. 95-96; O'Shea and Valdez 2009, pp. 9-17; Wiles and Worthington 2002, pp. 7, 13). The Pacific sheath-tailed bat is nocturnal and typically emerges around dusk to forage on insects (Craig et al. 1993, p. 51; Wiles and Worthington 2002, p. 13).

The Pacific sheath-tailed bat populations have declined drastically in the Mariana Islands, and the subspecies is now known to occur on only Aguiguan. While populations of other Pacific sheath-tailed bat subspecies appear to be healthy in some locations, mainly in the Caroline Islands, they have also declined drastically in other areas, including Independent and American Samoa, and Fiji (Bruner and Pratt 1979, p. 3; Grant et al. 1994, pp. 133-134; Wiles et al. 1997, pp. 222-223; Wiles and Worthington 2002, pp. 17-19). For example, populations of sheath-tailed bats (

E. s. semicaudata

) were noted to precipitously decline from American Samoa in the 1970s (Grant et al. 1994, pp. 133-134). It is speculated that disturbance of caves where the sheath-tailed bats roosted by successive storms contributed to the decline of sheath-tailed bats; however, it was noted that some caves were still inhabited by swiftlets (Grant et al. 1994, p. 134). Other factors contributing to the decline of sheath-tailed bats in American Samoa may include starvation during extended storms, human disturbance of caves, bombing and shelling during World War II, pesticides, and guano mining; however, the exact causes of sheath-tailed bat population declines in the American Samoa and other South Pacific islands are still uncertain (Grant et al. 1994, pp. 135-136). In contrast, large numbers of individuals of the sheath-tailed bat subspecies

E. s. palauensis

were readily observed by Wiles et al. in the 1990s (1997, p. 224).

In summary, the Pacific sheath-tailed bat (

E. s. rotensis

), once found on multiple islands on Guam and the Marianas, has been reduced to a single, small remaining population. The species has exhibited a significant decline from its initial numbers observed on Guam, Rota, Aguiguan, Tinian, Saipan, and its persistence in a single remaining population renders it vulnerable to extinction. The remaining population of the Pacific sheath-tailed bat continues to experience threats due to continued habitat loss and destruction from agriculture, urban development, nonnative animals, and typhoons. In addition, predation by monitor lizards, and possible predation by the brown tree snake, may contribute to the observed decline of the Pacific sheath-tailed bat.

Slevin's Skink

Slevin's skink (

Emoia slevini,

guali'ek halom tano) is a small lizard in the reptile family Scincidae, the largest lizard family in number of worldwide species. Slevin's skink was first described in 1972 by Walter C. Brown and Marjorie V.C. Falanruw, which is the most recent and accepted taxonomy (Brown and Falanruw 1972, p. 107). It

is the only lizard endemic to the Mariana Islands and is on the Government of Guam's Endangered Species List (Fritts and Rodda 1993, p. 3; Rodda et al. 1997, p. 568; Rodda 2002, p. 2; CNMI DFW 2005, p. 174; GDAWR 2006, p. 107; Guam Department of Agriculture 2014, in litt.). Slevin's skink previously occurred on the southern Mariana Islands (Guam, Cocos Island, Rota, Tinian, and Aguiguan), where it is now extirpated, except from Cocos Island off of Guam, where it was recently rediscovered (Fritts and Rodda 1993, p. 2; Steadman 1999; Lardner 2013, in litt.).

Surveys conducted in the 1980s and 1990s show that Slevin's skink was present on the northern islands of Sarigan, Guguan, Alamagan, Pagan, and Asuncion (Berger et al. 2005, pp. 174-175; GDAWR 2006, p. 107; Vogt 1997, in litt.); however, none were captured on Anatahan or Agrihan or ever reported historically from these islands (Berger et al. 2005, p. 175; Rodda et al. 1991, p. 202). The skink has not yet been reported from the southern island of Saipan, or the northern islands of Farallon de Medinilla, Maug, or Uracas. The densest population was on Alamagan (island area of 2,800 ac; 1,130 ha) in the early 1990s, but researchers believe that overgrazing by introduced ungulates may preclude the long-term viability of that population (Rodda 2002, p. 3; Fritts and Rodda 1993, p. 1). The catch rate (number of lizards captured per hour) quadrupled on Sarigan in a survey conducted in 2007, after eradication of feral ungulates from the island in 1998 (Vogt 2007, p. 5-5; Kessler 2011, p. 322). Its current status on Aguiguan, Guguan, Pagan, and Asuncion is unknown.

Slevin's skink measures 3 in (77 mm) from snout to cloaca vent (the opening for reproductive and excretory ducts), although length can vary slightly (Vogt and Williams 2004, p. 65). Fossil remains indicate its prehistoric size was much larger, up to 4.3 in (110 mm) in length (Rodda 2010, p. 3). Slevin's skink is darkly colored, from olive to brown, with darker flecks in a checkerboard pattern, and a light orange to bright yellow underside (Vogt and Williams 2004, p. 65). Their skin tends to be shiny, and is very durable and tough. Juveniles may appear cream-colored (Vogt and Williams 2004, p. 65; Rodda 2010, p. 3).

Slevin's skink is a fast-moving, alert, insectivorous lizard, typically found on the ground or at ground level, and active during the day. Based on both older and more recent observations, the species occurs in the forest ecosystem, with most individuals observed on the forest floor using leaf litter as cover (Brown and Falanruw 1972, p. 110; GDAWR 2006, p. 107; Cruz et al. 2000, p. 21; Lardner 2013, in litt.). Occasionally, individuals were observed in low hollows of tree trunks (Brown and Falanruw 1972, p. 110). It is a social species, seen often in the company of other individuals, including other nonnative skink species (Vogt and Williams 2004, pp. 59, 65). The females carry their eggs internally and give birth to live young (Brown 1991, pp. 14-15). Other specific life-history or habitat requirements of Slevin's skink are not well documented (Rodda 2002, p. 3).

Slevin's skink was most numerous in the Mariana Islands during prehistoric times, before the introduction of other competing lizards and predators, and loss of native forest (Vogt and Williams 2004, p. 65; Berger et al. 2005, p. 175). After World War II, Slevin's skink had notably vanished from the larger southern Mariana Islands (Fritts and Rodda 1993, p. 4), which suggests the species may be sensitive to habitat destruction or changes in land use practices (Fritts and Rodda 1993, p. 4; Berger et al. 2005, p. 174). Slevin's skink had not been recorded on Guam since 1945 or on Cocos Island since the early 1990s (Rodda and Fritts 1992, p. 171; Campbell 2011, in litt.), until a specimen was captured on Cocos Island in January of 2011 (Campbell 2011, pers. comm.). Over half the island is developed for a hotel, and it is a tourist destination (Fritts and Rodda 1993, p. 2). Only about 25 ac (10 ha) of suitable habitat is available on Cocos Island, and it is periodically overwashed during typhoons (Fritts and Rodda 1993, pp. 2, 5). The northern islands of its known occurrence provide less than 19,843 ac (8,030 ha) of land area, not all of which is suitable habitat. Slevin's skink is no longer found on the larger southern islands of Guam, Rota, and Tinian, which combined, provide the largest land area, 179,892 ac (72,800 ha). This species no longer occurs in 90 percent of its historical range.

In summary, once widespread, the remaining known populations of Slevin's skink are made up of a few individuals on Cocos Island, and occurrences of undetermined numbers of individuals on Alamagan and Sarigan. Populations of Slevin's skink are decreasing from initial numbers observed on Cocos Island, Alamagan, Pagan, and Asuncion, and it has not been reobserved on Guam, Rota, Tinian, and Aguiguan; the species has been lost from 90 percent of its former range. The remaining populations of Slevin's skink are at risk, due to continued habitat loss and destruction from agriculture, urban development, nonnative animals, and typhoons. Predation by rats, monitor lizards, and possible predation by the brown tree snake (if the snake is introduced to other islands), also contribute to the decline of Slevin's skink.

Mariana Eight-Spot Butterfly

The Mariana eight-spot butterfly (

Hypolimnas octocula marianensis

), a butterfly in the Nymphalidae family, is known solely from the islands of Guam and Saipan, in the forest ecosystem (Schreiner and Nafus 1996, p. 2; Schreiner and Nafus 1997, p. 26). It may be extirpated from Saipan (Schreiner and Nafus 1997, p. 26). This subspecies was originally described by Butler and is recognized as a distinct taxon in Swezey (1942, p. 35), the most recent and accepted taxonomy for this species. Like most nymphalid butterflies, orange and black are the two primary colors exhibited by this subspecies. The males are smaller than the females by at least a third or more in size. Males are predominantly black with an orange stripe running vertically on each wing. The stripe on the hindwings exhibits small black dots in a vertical row. Overall, the females appear more orange in color than the males, and black bands across the apical (top) margins of both pair of wings are exhibited. Along the inner margin of these black bands, large white spots are exhibited across the entire length of the wings (Schreiner and Nafus 1997, pp. 15, 26-27). The caterpillar larva of this species is black in color with red spikes and a black head, differentiating it from similar-appearing caterpillars including

Hypolimnas bolina, H.

anomala,

and

Pipturus

spp. (Schreiner and Nafus 1996, p. 10; Schreiner and Nafus 1997, p. 26).

The larvae of this butterfly feed on two native plants,

Procris pedunculata

(no common name), and

Elatostema calcareum

(tapun ayuyu) (Schreiner and Nafus, 1996, p. 1). Both of these forest herbs (family Urticaceae) are found only on karst substrate within the forest ecosystem, draped over boulders and small cliffs, presumably out of reach of browsing ungulates (Schreiner and Nafus 1996, p. 1; Rubinoff 2013, in litt.). When adult butterflies were observed, they were always in proximity to the host plants (Rubinoff 2011, in litt.; Rubinoff 2013, p. 1). Both of the host plant species are rare in their range, and both plants are believed to be susceptible to feral ungulate grazing based upon anecdotal observations indicating they occur only in the extremely rugged limestone karst terrain believed to be avoided by most

ungulates (Rubinoff 2013, in litt.). The two host plants have been recorded on the islands of Guam, Rota, Saipan, and Tinian (Schreiner and Nafus 1996, p. 2; Schreiner and Nafus 1997, p. 26; Harrington et al. 2012, in litt.; Rubinoff and Haines 2012, in litt.; Rubinoff, in litt. 2013). However, despite recent surveys (2011-2013) on Rota, Tinian, and Saipan, the Mariana eight-spot butterfly is currently known only from the island of Guam (Schreiner and Nafus 1996, p. 2; Schreiner and Nafus 1997, p. 26; Rubinoff and Haines 2012, in litt.; Rubinoff 2013, in litt. 2013). There are 11 known populations of the Mariana eight-spot butterfly on Guam (Schreiner and Nafus 1996, p. 2; Schreiner and Nafus 1997, p. 26; Rubinoff and Haines 2012, in litt.; Rubinoff 2011, in litt.; Rubinoff 2013, in litt.). Several areas were found that supported host plants on Saipan in 1995; however, no individuals of the Mariana eight-spot butterfly were seen, and it may be extirpated on Saipan (Schreiner and Nafus 1997, p. 26).

In summary, the Mariana eight-spot butterfly has been lost from one of the two islands where it formerly occurred. This butterfly is dependent upon two relatively rare host species, both of which are susceptible to the effects of ungulate grazing. The Mariana eight-spot butterfly is vulnerable to the impacts of continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, and typhoons. Herbivory of its host plants by nonnative animals, combined with direct predation by ants and parasitic wasps, contribute to the decline of the Mariana eight-spot butterfly.

Mariana Wandering Butterfly

The Mariana wandering butterfly (

Vagrans egistina

), is endemic to the islands of Guam and Rota in the Mariana archipelago, in the forest ecosystem. This butterfly was originally named

Issoria egistina

(Swezey 1942, p. 35). In 1934, Hemming published the genus

Vagrans

as a replacement name for the genus

Issoria.

Schriener and Nafus (1997) recognize this species as

Vagrans egistina,

which is the most recent and accepted taxonomy.

Like most nymphalid butterflies, the Mariana wandering butterfly is primarily orange and black in coloration. This species is largely black in appearance with a prominent orange irregular pattern extending from the forewings to the hindwings. Obvious stripes or rows of spots are lacking (Schreiner and Nafus 1997, plate 9). The caterpillar larva life stage of this species is brown in color with black-colored spikes (Schreiner and Nafus 1996, p. 10).

The Mariana wandering butterflies are known to be good fliers, and in earlier times, probably existed as a series of meta-populations (Harrison et al. 1988, p. 360), with considerable movement and interbreeding between local and stable populations and continued colonization and extinction in disparate localities. The larvae of this butterfly feed on the plant species

Maytenus thompsonii

(luluhut) in the Celastraceae family, which is endemic to the Mariana Islands (Swezey 1942, p. 35; Schreiner and Nafus 1996, p. 1). The host plant

M. thompsonii

is known to occur within the forest ecosystem on Guam, Rota, Saipan, and Tinian (Vogt and Williams 2004, p. 121).

Historically, the Mariana wandering butterfly was originally collected and described from the island of Guam where it was considered to be rare, but widespread (Swezey 1942, p. 35). The species has not been observed on Guam since 1979, where it was last collected in Agana. Currently, it is considered likely extirpated from Guam (Schreiner and Nafus 1996, pp. 1-2; Rubinoff 2013, in litt.). The Mariana wandering butterfly was first collected on Rota in the 1980s (Schreiner and Nafus 1996, p. 10). During several 1995 surveys on Rota, it was recorded at only one location among six different sites surveyed (Schreiner and Nafus 1996, pp. 1-2). From June through October 2008, extensive surveys for the Mariana wandering butterfly were conducted on the island of Tinian under the direction of the Service. While several

Maytenus thompsonii

host plant population sites were identified in limestone forest habitat, no life stages of the Mariana wandering butterfly were observed (Hawley in litt., 2009, pp. 1-9).

Although considered extirpated from Guam, whether the Mariana wandering butterfly continues to exist on Rota is unknown, as is its possible occurrence on other islands where its host plants are found. Several years of seasonal surveys are needed to determine the status of this species, but we do know that if it persists, it is likely in very low numbers as it has not been observed in many years. Any remaining populations of the Mariana wandering butterfly continue to be at risk from ongoing habitat loss and destruction by rats and typhoons. Herbivory of its host plant by nonnative animals, combined with direct predation by ants and parasitic wasps, contribute to the decline of the Mariana wandering butterfly.

Rota Blue Damselfly

The Rota blue damselfly (

Ischnura luta

) is a small damselfly endemic to the island of Rota and found within the stream ecosystem. Grouped together with dragonflies in the order Odonata, damselflies fall within the suborder Zygoptera. The Rota blue damselfly belongs to the family Coenagrionidae, and it is the only known damselfly species endemic to the Mariana Islands. This species was first described in 2000 (Polhemus et al. 2000, pp. 1-2) based upon specimens collected in 1996. The species is relatively small in size, with males measuring 1.3 in (34 mm) in body length, with forewings and hindwings 0.7 in (18 mm) and 0.67 in (17 mm) in length, respectively. Both sexes are predominantly blue in color, particularly the thorax and portions of the male's abdomen are brilliant, iridescent blue. Both sexes have a yellow and black head with some yellow coloration on the abdomen. Females of this species may be distinguished by their slightly smaller size and somewhat paler blue body color (Polhemus et al. 2000, pp. 1-8).

Resembling slender dragonflies, damselflies are readily distinguished by their trait of folding their wings parallel to the body while at rest rather than holding them out perpendicular to the body. The general biology of narrow-winged damselflies includes territorial males that guard areas of habitat where females will lay eggs (Moore 1983a, p. 89; Polhemus and Asquith 1996, pp. 2-7). During copulation, and often while the female lays eggs, the male grasps the female behind the head with terminal abdominal appendages to guard the female against rival males; thus males and females are frequently seen flying in tandem. Adult damselflies are predaceous and feed on small flying insects such as midges and other flies.

The immature larval life stages (naiads) of the vast majority of damselfly species are aquatic, breathe through flattened abdominal gills, and are predaceous, feeding on small aquatic invertebrates or fish (Williams 1936, p. 303). Females lay eggs in submerged aquatic vegetation or in mats of moss or algae on submerged rocks, and hatching occurs in about 10 days (Williams 1936, pp. 303, 306, 318; Evenhuis et al. 1995, p. 18). Naiads may take up to 4 months to mature (Williams 1936, p. 309), after which they crawl out of the water onto rocks or vegetation to molt into winged adults, typically remaining close to the aquatic habitat from which they emerged. Adults have only been observed in association with the single perennial stream on Rota; therefore, we

believe the larval stage of the Rota blue damselfly is aquatic.

The Rota blue damselfly was only first discovered in April 1996, when a few individuals were observed and one male and one female specimen were collected outside the Talakhaya Water Cave (also known as Sonson Water Cave) located below the Sabana plateau (Polhemus et al. 2000, pp. 1-8; Camacho et al. 1997, p. 4). The size of the population at the time of discovery was estimated to be small and limited to the stream area near the mouth of the cave. The primary source of the stream is springwater emerging at the limestone-basalt interface below the highly permeable limestone of the Sabana plateau (Polhemus et al. 2000, pp. 1-8; Keel et al. 2011, p. 1). This spring water also serves as the main source of fresh water supply for the population of Rota (Polhemus et al. 2000, pp. 1-8; Keel et al. 2011, p. 1). A concrete collection structure with associated piping has been built into and surrounding the entrance of the water cave. This catchment system and a smaller, adjacent catchment deliver approximately 2.7 to 3.8 million liters-per-day (0.7 to 1 million gallons) of water to Rota's municipal system (Keel et al. 2011, pp. 29-30) (see “Stream Ecosystem,” above, and

Factor E. Other Natural or Manmade Factors Affecting Their Continued Existence,

“Water Extraction,” below, for further discussion).

Eighteen years elapsed between the original discovery of the species in 1996 and the next known survey for the Rota blue damselfly. In January 2014, two male specimens were observed flying above a portion of the stream located at approximately 770 ft (235 m) in elevation, and below the Talakhaya (Sonson) Water Cave (Richardson 2014, in litt.). No specimens were observed immediately in the vicinity of the water cave entrance, and no fish were observed in the stream immediately below the cave entrance (Richardson 2014, in litt.), a notable observation because many damselfly species endemic to Pacific islands are known to be susceptible to predation by nonnative fish species that eat the naiad life stage of the damselfly. Predation by nonnative fish is a serious threat to the Hawaiian

Megalagrion

damselfly naiads (Englund 1999, pp. 235-236). Eggs laid in vegetation or on rocks in streams hatch in about 10 days and develop into naiads. Naiads take approximately 4 months to mature before emerging from the water (Williams 1936, pp. 303, 306, 309, 318).

Fish predation has been an important factor in the evolution of behavior in damselfly naiads in continental systems (Johnson 1991, p. 8), and damselflies in the wider-ranging

Ishnura

(as opposed to the Hawaiian

Megalagrion

) may have developed avoidance behaviors (Polhemus 2014, pers. comm.). On a survey of the stream (Okgok River, also known as Babao) fed by the Talakhaya (Sonson) Water Cave, the presence of four native fish species was noted: The eel

Anguilla marmorata,

the mountain gobies

Stiphodon elegans

and

Sicyopus leprurus,

and the flagtail, or mountain bass,

Kuhlia rupestris

(Camacho et al. 1997, p. 8). Densities of these native fish were low, especially in areas above the waterfall. Gobies can maneuver in areas of rapidly flowing water by using ventral fins that are modified to form a sucking disk (Ego 1956, in litt.). The flagtails were only abundant in the lower reach of the stream. Freshwater gobies in Hawaii are primarily browsers and bottom feeders, often eating algae off rocks and boulders, with midges and worms being their primary food items (Ego 1956, in litt.; Kido et al. 1993, p. 47). It can only be speculated that the Rota blue damselfly may have adapted its behavior to avoid the benthic feeding habits of native fish species. The release of aquarium fish into streams and rivers of Guam is well documented, but currently, no nonnative fish have been found in the Rota stream (Tibbatts 2014, in litt.).

The Rota blue damselfly appears to be extremely limited in range and researchers remain perplexed by its absence from other Mariana Islands (Polhemus et al. 2000, p. 8). Particularly striking is the fact that it has never been collected on Guam, despite the islands' larger size and presence of over 100 rivers and streams. The Rota blue damselfly's population site is afforded some protection from human impact by its remote and relatively inaccessible location; however, a reduction or removal of stream flow due to increased interception for municipal usage, and from lower water quantities resulting from the effects of climate change, could eliminate the only known population of the species (See “Stream Ecosystem,” above, and

Factor E. Other Natural or Manmade Factors Affecting Their Continued Existence,

below, for further discussion). Introduction of nonnative fish into the stream could also impact or eliminate the Rota blue damselfly naiads, leading to its extirpation. In addition, low numbers of individuals result in loss of vigor and genetic representation and contribute to the decline of the Rota blue damselfly.

Humped Tree Snail

The humped tree snail (

Partula gibba;

akaleha), in the Partulidae family, is endemic to the forest ecosystem on the Mariana Islands of Guam, Rota, Aguiguan, Saipan, Tinian, Anatahan, Sarigan, Alamagan, and Pagan. The humped tree snail was first collected on Guam in 1819 by Quoy and Gaimard during the Freycinet Uranie expedition of 1817-1819 and was once considered the most abundant tree snail on Guam (Crampton 1925, pp. 8, 25, 60). Currently, the humped tree snail is known from the islands of Guam (Hopper and Smith 1992, p. 81; Smith et al. 2009, pp. 10, 12, 16), Rota (Smith 1995, p. 1; Bauman 1996, pp. 15, 18), Saipan (Hadfield 2010, pp. 20-21), Sarigan (Hadfield 2010, p. 21) Alamagan (Bourquin 2002, p. 30), and Pagan (Hadfield 2010, pp. 8-14), in the forest ecosystem. The humped tree snail may occur on Aguiguan, but was not located on a survey by Smith in 2006 (Smith 2013, p. 14). It is believed that this species is no longer extant on Tinian due to loss of habitat to agriculture and the introduction of nonnative snails (Smith 2013, p. 24), and that it is no longer extant on Anatahan due to volcanic activity in 2003 and 2005 (Kessler 2011, pp. 321, 323).

The shell of the humped tree snail can be left- or right-coiling, conic-ovate, translucent, and engraved longitudinally with equal lines. The color ranges from white to brown, and has a pointed apex colored rose-red, with a milky white suture. Adult snails are from 0.6 to 0.7 in (14 to 18 mm) long, and 0.4 to 0.6 in (10 to 14 mm) wide, with 4

1/2

whorls, the last of which is the largest (Pilsbry 1909-1910 in Crampton 1925, p. 60; Smith et al. 2009, p. 2). In general, partulid snails reproduce in less than 1 year, at which time they can produce up to 18 young each year, and may live up to 5 years. The humped tree snail is oviviparous (gives birth to live young). They are generally nocturnal, live on bushes or trees, and feed primarily on dead or decaying plant material.

The humped tree snail occurs in cool, shaded forest habitat as observed by Crampton and others (Crampton 1925, pp. 31, 61; Cowie 1992, pp. 175-176) with high humidity and reduced air movement that prevents excessive water loss. Crampton (1925, pp. 31, 61) described the habitat requirements of the partulid trees snails as having “sufficiently high and dense growth to provide shade, to conserve moisture, and to effect the production of a rich humus. Hence the limits to the areas occupied by Partulae are set by the more

ultimate ecological conditions which determine the distribution of suitable vegetation.” Crampton further notes that the Mariana Islands partulid tree snails live on subcanopy vegetation and are not found in high canopy. There are no known natural predators of these snails, although many of these partulid species are currently preyed on by alien invertebrates such as flatworms and slugs (Cowie 1992, p. 175).

Following is a brief historical overview of the humped tree snail in the Mariana archipelago. Crampton (1925, pp. 8, 25, 60) first observed the humped tree snail on Guam, in at least 39 sites, totaling more than 3,000 individuals. In 1989, Hopper and Smith (1992, p. 81) resurveyed 34 of Crampton's 39 sites and did not locate any live individuals; however, they discovered individuals at a new site not noted by Crampton. Populations on Guam have since declined from hundreds to fewer than 50 individuals (Smith et al. 2009, p. 11). Bauman surveyed Rota and reported finding live humped tree snails at 5 out of 25 former sites (Bauman 1996, pp. 15, 18). The largest of these populations may have totaled as many as 1,000 snails. However, this population was located along the main road of Rota and was subsequently cleared for development (Miller 2007, pers. comm.). Four other populations on Rota in 2007 were small and totaled fewer than 600 individuals.

The humped tree snail was discovered on Aguiguan in 1952, in six colonies (biologists often refer to snail populations as “colonies”) (Kondo 1970, pp. 75, 81). In 1992, two separate surveys reported snails were observed at four locations on Aguiguan (Craig and Chandran 1992; Smith 1995), but by 2008, no live snails were found on this island (Smith 2013, p. 14). Crampton (1925) was unable to visit Tinian, although he states that Partulae were known from that island (1925, p. 6). Smith reported finding only very old shells on two surveys (2006 and 2008) of Tinian (Smith 2013, p. 6). On Saipan, Crampton collected almost 7,000 humped tree snails in 1925 (Crampton 1925, p. 62). By 1991, Smith and Hopper (1994, p. 11) could not find any live snails at 12 sites visited on the island; however, 2 small populations were later discovered, one in 2002, in the central forest area, and another in a mangrove wetland in 2010 (Bourquin 2002, in litt.; Hadfield 2010, pp. 20-21).

In 1994, Kurozumi reported approximately 20 individuals from Anatahan; however, these were possibly extirpated due to violently destructive volcanic eruptions between 2003 and 2005 (Kessler 2011). Kurozumi also reported the humped tree snails from Sarigan in 1994, and the population appears to be increasing as a result of the removal of ungulates. A survey of Sarigan in 2006 found the healthiest population in native forest at an elevation of approximately 1,300 ft (400 m) (Smith 2006 in Martin et al. 2008, p. 8-1). The species was first reported on Alamagan by Kondo in 1949, with over 50 individuals collected from wet forest (Easley 1970, p. 87). The populations seem to have declined on Alamagan by over 70 percent for individuals and approximately 27 percent for populations since that time (Kurozumi 1994). The humped tree snail was first reported from Pagan by Kondo in 1949 (Easley 1970, p. 87). Populations persist on Pagan although the same decline is seen here as for Alamagan (Kurozumi 1994).

In summary, populations of the humped tree snail are rapidly decreasing from initial numbers observed, and with continued habitat loss and predation by nonnative species, are at risk, with the possible exception of those on Sarigan, as ungulates have been removed from that island (see “Conservation Efforts To Reduce Habitat Destruction, Modification, or Curtailment of Its Range,” below). However, predation by rats remains a threat to the humped tree snail on Sarigan (Kessler 2011, p. 320).

Recent data also suggest that the individuals identified as humped tree snails on Rota may be a different species (Hadfield 2010, pp. 20-21). Because these recent findings have not been published, and data on population numbers and number of individuals has not been determined, we are still treating the humped tree snail as a single species.

Langford's Tree Snail

Langford's tree snail (

Partula langfordi;

akaleha), in the Partulidae family, is endemic to the forest ecosystem of the island of Aguiguan. Langford's tree snail was first collected and described by Kondo while working on biological control agents in the early 1950s (Kondo 1970, 18 pp.). Kondo's taxonomic work is the most recent and accepted taxonomy for this species. This tree snail has not been observed in the wild since 1992, when one live individual was observed on the northwest terrace of the island (Berger et al. 2005, p. 154). Surveys conducted in 2006 and 2008 revealed only old shells of dead

P. langfordi

(Smith 2013, p. 14).

Langford's tree snail has a dextral (to the right or clockwise from the opening of the shell at the lower right, as opposed to sinistral, to the left, or counterclockwise) shell, described by Kondo (1970, pp. 75-77) as being ovate-conic and moderately thin. The holotype of this species has a length of 0.6 in (14 mm), a diameter of 0.4 in (9 mm), and an aperture length of 0.3 in (8 mm). It has a spire of five whorls that are slightly convex, with an obtuse apex. Its aperture is oblong-ovate with the white mouth projections thickened and expanded. It is buff colored superimposed by maroon.

Although much less studied than related partulid snails from the Mariana Islands, the biology of Langford's tree snail is believed to be the same. See “Humped tree snail (

Partula gibba

),” above, for details.

Historically, Langford's tree snail is known only from the island of Aguiguan. In the 1970 survey of Aguiguan, it was noted that Langford's tree snail was collected from an area where it occurred sympatrically with the humped tree snail (Easely 1970, p. 89). The mixed populations were not uniformly distributed, but occurred in small colonies with large unoccupied areas between the colonies. In five of the sites, the Langford's tree snail outnumbered the humped tree snail and it appeared that humped tree snails were more numerous and dominant in the western portion of the site while Langford's tree snails were dominant in the eastern portion of the site (Kondo 1970, p. 81). Three other colonies of Langford's tree snail were collected, two on the north coast and one on the west end of Aguiguan (Kondo 1970, p. 81). A total of 464 adults were collected from 7 sites (Kondo 1970, p. 81). In 1985, five adult Langford's tree snails were collected from the west end of the island (Smith 1995). The last survey in which the species was detected in the wild was conducted in 1992, and one live snail was observed on the northwest terrace of the island (Smith 1995). Surveys of Aguiguan in 2006 and 2008 failed to locate any live Langford's tree snails (Smith 2013, p. 14).

In 1993, the University of Nottingham in England had six young and four adult Langford's tree snails in captivity. By 1994, two adult snails remained. Unfortunately, at the end of 1994, the last two Langford's tree snails died (Pearce-Kelly et al. 1995).

The 2005 Comprehensive Wildlife Conservation Strategy for CNMI (Division of Fish and Wildlife) (Berger et al. 2005) states that “all Partulid snails are selected as a species of special conservation need” (p. 153), and that “[Crampton] found as many as 31 snails on the underside of a single leaf of caladium” (p. 155) (demonstrating that it would be easy to miss a large number

of snails if that one particular leaf were missed during a survey). This strategy outlines conservation actions for Langford's tree snail, including more numerous and intensive surveys, removal of goats from Aguiguan island, control of nonnative species, and reforestation with native plants (pp. 158-159). Given that so few surveys have been conducted on Aguiguan, and only previously surveyed sites were ever revisited, it is likely Langford's tree snail may be found.

Guam Tree Snail

The Guam tree snail (

Partula radiolata;

akaleha), in the Partulidae family, is endemic to the forest ecosystem of Guam. The Guam tree snail was first collected by Quoy and Gaimard during the French

Astrolabe

expedition of 1828 and was initially named

Bulimus

(

Partula

)

radiolatus

by Pfeiffer in 1846, which he changed to

Partula radiolata

in 1849 (Crampton 1925, p. 34). Crampton's 1925 taxonomic work is the most recent and accepted taxonomy for this species.

The shell of the Guam tree snail is pale straw-colored with darker streaks and brown lines, and has impressed spiral lines. Adult length is 0.5 to 0.7 in (13 to 18.5 mm), and width is 0.3 to 0.5 in (8 to 12 mm), with five slightly convex whorls (Pilsbry 1909-1910 in Crampton 1925, p. 35; Smith et al. 2008 in Kerr 2013, p. 10). The biology of the Guam tree snail is very similar to that of the humped tree snail (see “Humped tree snail (

Partula gibba

),” above, for further description). The Guam tree snail prefers the same cool, shaded forest habitat as the humped tree snail and Langford's tree snail, described above.

Historically, suitable habitat for the Guam tree snail was widely available prior to World War II, and included strand vegetation, forested river borders, and lowland and highland forests (Crampton 1925, pp. 36-37), and Crampton found “it occurs almost everywhere on the island where suitable vegetation exists,” although historical population numbers are unknown. Crampton (1925, pp. 38-40) found the Guam tree snail at 37 of 39 sites surveyed on Guam and collected a total of 2,278 individuals. The actual population sizes were probably considerably larger since the purpose of Crampton's collections was to evaluate geographic differences in shell patterns and not to assess population size. In 1989, Hopper and Smith (1992, p. 78) resurveyed 34 of Crampton's 39 sites on Guam and an additional 13 new sites. They observed that 9 of the original 34 sites resurveyed supported these snails; however, the Crampton site identified as having the largest remaining population of the Guam tree snail (estimated at greater than 500 snails) had been completely eliminated by the combined effects of land clearing for a residential development and a subsequent series of typhoons in 1990, 1991, and 1992 (Smith 1995).

Of the 13 new sites surveyed by Hopper and Smith in 1989, 7 supported populations of the Guam tree snail. One of these populations was eliminated by wildfires that burned into ravine forest occupied by the snails in 1991 and 1992 (Smith and Hopper 1994). Further surveys by Smith (1995) revealed five new populations of the Guam tree snail. According to Smith, by 1995, there were 20 sites that still supported small populations of the Guam tree snail. Snails were moved from 1 of these 20 sites to a new location due to the development of a golf course (Smith 1995). In 2003 an additional small colony (fewer than 100 snails) was found on the U.S. Naval Base (Smith 2006, pers. comm.). A smaller colony (20 to 25 snails) was found in 2004 along the Lonfit River (Smith 2006, pers. comm.). Additionally, surveys on the Guam Naval Magazine located another new population, with shells of tree snails in abundance on the ground at all locations (Miller 2006, pers. comm.; JGPO-NavFac 2014 apps, pp. 27, 59). Further surveys of lands leased by the Navy in 2009 indicated a decline in densities of tree snails by about half, which was attributed to a loss of native understory (Smith et al. 2009, pp. 13-14). In 2011, a survey of Andersen AFB revealed a single colony of Guam tree snail (Joint Region Marianas (JRM) Integrated Natural Resources Management Plan (INRMP) Appendices 2012, p. 15).

Populations of the Guam tree snail continue to decline, from first observations of thousands of individuals by Crampton, down to 20 colonies or fewer today. Continued loss of habitat due to development and removal of native plants by ungulates contributes to this loss.

Fragile Tree Snail

The fragile tree snail (

Samoana fragilis;

akaleha), in the Partulidae family, is known from the forest ecosystems of Guam and Rota. This species was first described as

Partula fragilis

by Férussac in 1821 (Crampton 1925, p. 30). It is the only species representing the genus of

Samoana

in the Mariana Islands. The fragile tree snail was first collected on Guam in 1819 by Quoy and Gaimard during the Freycinet Uranie expedition of 1817 to 1819 (Crampton 1925, p. 30). Crampton's 1925 taxonomic work for this species is the most recent and accepted taxonomy for this species.

The conical shell of the fragile tree snail is 0.5 to 0.6 in (12 to 16 mm) long, 0.4 to 0.5 in (10 to 12 mm) wide, and is formed by four whorls that spiral to the right. The common name is derived from the thin, semi-transparent nature of the shell. The shell has delicate spiral striations intersected by transverse growth striations. The background color is buff, tinted by narrow darker marks and whitish banding that are derived from the internal organs of the animal that are visible through the shell (Mollendorff 1894 in Crampton 1925, p. 31). The biology and habitat for this partulid tree snail are the same as those described for the three partulid species described above (see the “Humped tree snail (

Partula gibba

),” above).

Historically, the fragile tree snail was known from 13 populations on Guam and 1 population on Rota (Crampton 1925, p. 30; Kondo 1970, pp. 86-87). Easely (1970, p. 86) documented the 1959 discovery of the fragile tree snail on Rota by R.P. Owen. The same area had been surveyed just 7 years earlier by Benavente and Kondo, in 1952, but the fragile tree snail was not observed (Easley 1970, p. 87). In 1989, Hopper and Smith (1992, p. 78) resurveyed Crampton's original sites plus 13 more, all on Guam. At that time, they found fragile tree snails at only six sites. The most recent surveys on Guam for the fragile tree snail were conducted in 2008 and 2011. Currently, two colonies are known on Guam (Smith et al., 2009, pp. 7, 13). The original site where this species was found on Rota was converted to agricultural fields and no living snails were found there in 1995; however, in 1996, a new colony was found on Rota in a different location (Bauman 1996, pp. 18, 21).

We lack quantitative estimates for the fragile tree snail (Bauman 1996, p. 21), but Crampton (1925, p. 30) originally described this species as rare and low in numbers. Available data indicates the number of known colonies has declined between 1925 and present, from approximately 14 colonies to only 3 colonies.

In summary, populations of the fragile tree snail are decreasing from initial numbers observed on Guam and Rota, and are at risk, due to continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, and typhoons. Trade of shells by collectors, combined with direct predation by rats and flatworms, also contribute to the decline of the fragile tree snail. Low numbers of

individuals contribute to population declines through loss of vigor and genetic representation.

Summary of Biological Status and Threats Affecting the 23 Species Proposed for Listing as Endangered or Threatened Species

Section 4 of the Act (16 U.S.C. 1533) and its implementing regulations (50 CFR part 424) set forth the procedures for adding species to the Federal Lists of Endangered and Threatened Wildlife and Plants. A species may be determined to be an endangered or threatened species due to one or more of the five factors described in section 4(a)(1) of the Act: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; and (E) other natural or manmade factors affecting its continued existence. Listing actions may be warranted based on any of the above threat factors, singly or in combination. Each of these factors is discussed below.

In considering what factors might constitute threats to a species, we must look beyond the exposure of the species to a particular factor to evaluate whether the species may respond to that factor in a way that causes actual impacts to the species. If there is exposure to a factor and the species responds negatively, the factor may be a threat and, during the status review, we attempt to determine how significant a threat it is. The threat is significant if it drives, or contributes to, the risk of extinction of the species such that the species warrants listing as an endangered or threatened species as these terms are defined in the Act. However, the identification of factors that could impact a species negatively may not be sufficient to warrant listing the species under the Act. The information must include evidence sufficient to show that these factors are operative threats that act on the species to the point that the species meets the definition of endangered or threatened under the Act.

If we determine that the level of threat posed to a species by one or more of the five listing factors is such that the species meets the definition of either endangered or threatened under section 3 of the Act, that species may then be proposed for listing as an endangered or threatened species. The Act defines an endangered species as “in danger of extinction throughout all or a significant portion of its range,” and a threatened species as “likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.” The threats to each of the individual 23 species proposed for listing in this document are summarized in Table 3, and discussed in detail below. Since there are 15 islands in the Mariana Islands, Table 4 (below) is provided as a supplement to Table 3, to allow the reader to better understand the presence of nonnative species addressed in this proposed rule that negatively impact the 23 species on an island-by-island basis.

Table 3—Summary of Primary Threats Identified for Each of the 23 Mariana Islands Species

Species

Ecosystem

Factor A

Development, military training, urbanization

Non-

native

animals

Non-

native

plants

Fire

Typhoons

Climate

change

Factor B

Over-

utilization

Factor C

Predation

and

herbivory

ungulates

Predation

and

herbivory

by NN

verte-

brates

Predation

and

herbivory

by NN

inverte-

brates

Factor D

Inadequate

existing

regulatory

mechanisms

Factor E

Species-

specific

Plants

Bulbophyllum guamense

R, BTS

Cycas micronesica

R, P, B, D, BTS

P, D

CAS

ORD

Dendrobium guamense

R, BTS

Eugenia bryanii

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