Endangered and Threatened Wildlife and Plants; Endangered Status for 16 Species and Threatened Status for 7 Species in Micronesia
Federal RegisterOct 1, 2015
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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; Endangered Status for 16 Species and Threatened Status for 7 Species in Micronesia
AGENCY:
Fish and Wildlife Service, Interior.
ACTION:
Final rule.
SUMMARY:
We, the U.S. Fish and Wildlife Service, determine endangered status under the Endangered Species Act of 1973, as amended, for 16 plant and animal species from the Mariana Islands (the U.S. Territory of Guam and the U.S. Commonwealth of the Northern Mariana Islands). We also determine threatened status for seven plant species from the Mariana Islands and greater Micronesia in the U.S. Territory of Guam, the U.S. Commonwealth of the Northern Mariana Islands, the Republic of Palau, and the Federated States of Micronesia (Yap). The effect of this regulation will be to add these 23 species to the Federal Lists of Endangered and Threatened Wildlife and Plants.
DATES:
This rule becomes effective November 2, 2015.
ADDRESSES:
This final rule is available on the Internet at
http://www.regulations.gov
and
http://www.fws.gov/pacificislands
. Comments and materials we received, as well as some of the supporting documentation used in preparing this final rule, are available for public inspection at
http://www.regulations.gov
. All of the comments, materials, and documentation that we considered in this rulemaking are available, by appointment, during normal business hours, at: U.S. Fish and Wildlife Service, Pacific Islands Fish and Wildlife Office, 300 Ala Moana Boulevard, Room 3-122, Honolulu, HI 96850; by telephone at 808-792-9400; or by facsimile at 808-792-9581.
FOR FURTHER INFORMATION CONTACT:
Kristi Young, Acting Field Supervisor, U.S. Fish and Wildlife Service, Pacific Islands Fish and Wildlife Office, 300 Ala Moana Boulevard, Room 3-122, 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 or ESA), a species may warrant protection through listing if it is endangered or threatened throughout all or a significant portion of its range. Listing a species as an endangered or threatened species can only be completed by issuing a rule. 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.
This rule will finalize the listing of 23 species from the Mariana Islands as endangered or threatened species, one of which (
Cycas micronesica
) also occurs in the Republic of Palau and the Federated States of Micronesia (Yap). For the sake of brevity, throughout this document we refer to these 23 species simply as the 23 Mariana Islands species. Sixteen of these species are listed as endangered species: Seven plants—
Eugenia bryanii
(no common name (NCN)),
Hedyotis megalantha
(pau dedu, pao doodu),
Heritiera longipetiolata
(ufa halumtanu, ufa halom tano),
Phyllanthus saffordii
(NCN),
Psychotria malaspinae
(aplokating palaoan),
Solanum guamense
(Biringenas halumtanu, birengenas halom tano), and
Tinospora homosepala
(NCN); and nine animals—the Pacific sheath-tailed bat (Mariana subspecies,
Emballonura semicaudata rotensis;
payeyi, paischeey), Slevin's skink (
Emoia slevini;
gualiik halumtanu, gholuuf), Mariana eight-spot butterfly (
Hypolimnas octocula marianensis;
ababbang, libweibwogh), Mariana wandering butterfly (
Vagrans egistina;
ababbang, libweibwogh), Rota blue damselfly (
Ischnura luta;
dulalas Luta, dulalas Luuta), fragile tree snail (
Samoana fragilis;
akaleha dogas, denden), Guam tree snail (
Partula radiolata;
akaleha, denden), humped tree snail (
Partula gibba;
akaleha, denden), and Langford's tree snail (
Partula langfordi;
akaleha, denden). Seven plant species—
Bulbophyllum guamense
(siboyas halumtanu, siboyan halom tano),
Dendrobium guamense
(no common name (NCN),
Cycas micronesica
(fadang, faadang),
Maesa walkeri
(NCN),
Nervilia jacksoniae
(NCN),
Tabernaemontana rotensis
(NCN), and
Tuberolabium guamense
(NCN)—are listed as threatened species.
Delineation of critical habitat requires, within the geographical area occupied by the species, identification of the physical or biological features essential to the species' conservation. Information regarding the life functions and habitats associated with these life functions is complex, and informative data are largely lacking for the 23 Mariana Islands species. A careful assessment of the areas that may have the physical or biological features essential for the conservation of the species and that may require special management considerations or protections, and thus qualify for designation as critical habitat, will require a thorough assessment. We require additional time to analyze the best available scientific data in order to identify specific areas appropriate for critical habitat designation. Accordingly, we find designation of critical habitat to be “not determinable” at this time.
The basis for our action.
Under the Endangered Species 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. We have determined that the 23 Mariana Islands 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 the synergistic effects of future climate change.
• Predation or herbivory by nonnative feral ungulates, rats, snakes, monitor lizards, slugs, flatworms, ants, and wasps.
• The inadequacy of existing regulatory mechanisms to prevent the introduction and spread of nonnative plants and animals.
• Direct impacts from ordnance and live-fire from military training, recreational vehicles, and exacerbated vulnerability to threats and, consequently, extinction, due to small numbers of individuals and populations.
Peer review and public comment.
We sought comments from independent specialists to ensure that all of our determinations are based on scientifically sound data, assumptions, and analyses. We also considered all
comments and information received during the comment periods and public hearings.
Previous Federal Actions
Please refer to the proposed listing rule, published in the
Federal Register
on October 1, 2014 (79 FR 59364), for previous Federal actions for these species prior to that date. The publication of the proposed listing rule opened a 60-day comment period, beginning on October 1, 2014, and closing on December 1, 2014. In addition, we published a public notice of the proposed rule on October 18, 2014, in the Marianas Variety, Marianas Variety Guam, and the Guam Pacific Daily News newspapers. On January 12, 2015 (80 FR 1491), we reopened the comment period for an additional 30 days and announced two public hearings, each preceded by public information meetings (January 27, 2015, on Guam; and January 28, 2015, on Saipan); and two separate public information meetings, one each on Rota (January 29, 2015) and Tinian (January 31, 2015). This second comment period closed on February 11, 2015. We published public notices in the local Marianas Variety and Pacific Daily News on January 23, 2015, in order to inform the public about the hearings and information meetings, as well as the reopening of the comment period. In total, we accepted public comments on the October 1, 2014, proposed rule (79 FR 59364) for 90 days.
Summary of Changes From Proposed Rule
In preparing this final rule, we reviewed and fully considered comments from the peer reviewers and public on the proposed listings for 23 species. This final rule incorporates the following substantive changes to our proposed rule, based on the comments we received:
(1) The proposed rule described the status of five plant species (four orchids:
Bulbophyllum guamense, Dendrobium guamense,
Nervilia jacksoniae,
and
Tuberolabium guamense;
and a plant in the family Primulaceae,
Maesa walkeri
) as meeting the definition of an endangered species under section 3(6) of the Act (any species which is in danger of extinction throughout all or a significant portion of its range). However, new information from further surveys has shown that these five plant species are more numerous on the island of Rota than previous data indicated, each with a population structure consisting of seedlings, juveniles, and adults. This new information indicates that these five plant species are not quite as imperiled throughout their ranges as previously understood at the time of the proposed rule. However, these species are still susceptible to habitat destruction and modification by nonnative plants and animals, fire, and the future effects of climate change on Rota. Additionally, at least 50 percent of their respective ranges occur on the island of Guam, where these species once occurred in abundance but now exist in very low numbers of individuals, and face similar threats as on Rota, in addition to habitat destruction and modification by urban development, military development and training, brown treesnakes (
Boiga irregularis
), and feral pigs (
Sus scrofa
).
The Act defines an endangered species as “any species which is in danger of extinction throughout all or a significant portion of its range,” and a threatened species as “any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.” Therefore, because the four orchid species (
Bulbophyllum guamense, Dendrobium guamense, Nervilia jacksoniae,
and
Tuberolabium guamense
) and
Maesa walkeri
appear relatively healthy on Rota, but face threats throughout all of their ranges, and have declined across at least 50 percent of their ranges (
i.e.,
on Guam), we have retained them in this final listing determination but have changed their status to threatened species, as they are at risk of becoming endangered within the foreseeable future throughout all of their ranges. All new data received during the comment period for these five species have been added to Description of the 23 Mariana Islands Species and Summary of Biological Status and Threats Affecting the 23 Mariana Islands Species, below. Further, our rationale for listing each of these five species as threatened species, versus endangered species, is discussed under Determination, below.
(2) We updated the section titled “Historical and Ongoing Human Impacts” under
The Mariana Islands,
below, to include recent changes in proposed military actions.
(3) We have corrected our original description of the political division of Micronesia. See “Political Division” under
The Mariana Islands,
below.
(4) We have added new island occurrences for three species addressed in this final rule.
Dendrobium guamense
was recently discovered on the island of Aguiguan—a brand new island record (Zarones 2015a, in litt.); the humped tree snail was recently observed on Tinian, an island on which the humped tree snail was previously thought to be extirpated (Naval Facilities Engineering Command Pacific (NavFac, Pacific) 2014, pp. 5-5, 5-7); and one individual of
Heritiera longipetiolata
was reported from Rota, an island on which it was thought this species was extirpated (Cook 2010, pers. comm. cited in CNMI Department of Land and Natural Resources (DLNR) 2014, in litt.). These three island additions have been placed under
Islands in the Mariana Archipelago,
Description of the 23 Mariana Islands Species, and Table 1, below.
(5) We have corrected the common names for many of the plant and animal species addressed in this final rule after consultation with a Chamorro and Carolinian language expert and a comment received from a peer reviewer. These changes can be observed in Table 1 and under Description of the 23 Mariana Islands Species, below.
(6) We have added the parenthetical “(Mariana subspecies)” to the common name of the Pacific sheath-tailed bat addressed in this rule, specifically the subspecies
Emballonura semicaudata rotensis,
to allow the reader to more easily distinguish between the four subspecies of Pacific sheath-tailed bats that are known by the same common name.
(7) Due to a comment we received from a peer reviewer, we have changed our general description of partulid (referring to a genus of tree snails in the Pacific) characteristics (see Description of the 23 Mariana Islands Species) to include that the mobility of partulids is more related to ambient precipitation and humidity, rather than with the time of day. Previous reports indicated that partulids are primarily nocturnal.
(8) Due to comments received from a peer reviewer and new information, we have expanded our description of the negative impacts associated with the manokwari flatworm, also known as the New Guinea flatworm (
Platydemus manokwari
), on the four tree snails under
Flatworm Predation on Tree Snails
under Summary of Biological Status and Threats Affecting the 23 Mariana Islands Species, below. This new information suggests that we had greatly underestimated the severity and scope of the threat posed by the manokwari flatworm in the proposed rule.
(9) Due to comments received by the U.S. Navy, and in light of the new 2014 Draft Supplemental Environmental Impact Statement (SEIS) and subsequent 2015 Final EIS, we updated the description of the Marine Corps relocation under “Historical and Ongoing Human Impacts,” below. We
cited the Final Supplemental EIS (SEIS) released in July of 2015, and associated changes, which include a proposal to construct and operate facilities on Guam (not Tinian) to support the training and operations of Marines and the removal of the proposal to create four ranges on Tinian since the associated training requirements satisfied by those four ranges are now the subject of another EIS (Commonwealth of the Northern Mariana Islands Joint Military Training (CJMT) EIS, described below). We also dropped “and Tinian” in the description of the revised proposed actions associated with the 2015 Final SEIS associated with the relocation. Additionally, we removed the construction of a deep-draft wharf in Apra Harbor and facilities to support the U.S. Missile Defense Task Force since this is no longer proposed on Guam (and is not addressed in the revised proposed action covered in the 2014 Draft SEIS or 2015 Final SEIS).
(10) Due to comments received by the U.S. Navy, and in light of the new 2015 Final SEIS, we updated the description of the Marine Corps relocation under “Historical and Ongoing Human Impacts,” below. The updates include the construction of a Marine Corps cantonment (main base) at Naval Computer and Telecommunications Station Finegayan, family housing on Andersen Air Force Base (AAFB), and a live-fire training range on AAFB-Northwest Field as the preferred alternatives. We noted that Orote Point, Pati Point, and Navy Barrigada are no longer preferred locations for any facilities to support the Marine Corps move.
(11) We have edited the section titled “Ordnance and Live-Fire Training” under
Factor E. Other Natural or Manmade Factors Affecting Their Continued Existence,
below. We changed the physical location of the ordnance and live-fire training, and subsequently the species impacted by this threat, due to changes presented in the Navy's 2014 Draft SEIS (Joint Guam Program Office (JGPO)-NavFac, Pacific 2014, p. ES-1) and 2015 Final SEIS (JGPO-NavFac, Pacific 2015, p. ES-11;
http://www.guambuildupeis.us/
), and the 2015 CNMI Joint Military Training Draft EIS/Overseas EIS (OEIS) (
http://www.cnmijointmilitarytrainingeis.com/about
). In this final rule, the species that are considered to be negatively impacted by ordnance and live-fire include the plants
Cycas micronesica, Heritiera longipetiolata, Psychotria malaspinae,
and
Tabernaemontana rotensis
and the humped tree snail, Mariana eight-spot butterfly, and Slevin's skink. This change is also noted under “Historical and Ongoing Human Impacts” and Table 3, below.
(12) We added new information to “Conservation Efforts to Reduce Disease and Predation” and “Conservation Efforts to Reduce Habitat Destruction, Modification, or Curtailment of Its Range,” below. In 2013, the U.S. Navy erected five new exclosures on Tinian, each with 1,000 mature individuals of
Cycas micronesica.
In 2014, the U.S. Navy funded $5.1 M towards brown treesnake projects in the Mariana Islands.
(13) Due to new data we received during the comment period, we added the Mariana eight-spot butterfly, Mariana wandering butterfly, and the Pacific sheath-tailed bat (Mariana subspecies) to “Small Number of Individuals and Populations,” below. A recent genetic analysis found no heterogeneity exists between three separate populations of the Mariana eight-spot butterfly on Guam (Lindstrom and Benedict 2014, p. 27). In fact, they found the genetic sequences studied to be identical, which is indicative that little population structure exists among these mobile insects, and that they have recently experienced a population bottleneck limiting genetic diversity for this species on Guam (Lindstrom and Benedict 2014, p. 27). Additionally, since there are no recent observations of the Mariana wandering butterfly, we have deduced that if a population exists, it does so in very small numbers and, therefore, faces the same threat of reduced genetic diversity as the Mariana eight-spot butterfly. A recent genetic analysis of the Pacific sheath-tailed bat (Mariana subspecies) found no genetic diversity among the only known extant population of this species (Oyler-McCance
et al.
2013, pp. 1,034-1,035). This new data, combined with the observed decrease in range from five islands formerly (Guam, Rota, Saipan, Tinian, and Aguiguan) to just one at present (Aguiguan), has led the Service to conclude that the Pacific sheath-tailed bat (Mariana subspecies) is at risk from low numbers of individuals and populations. We have added the two butterflies and bat addressed in this rule to the threat of small number of individuals and populations under Table 3, and
Factor E. Other Natural or Manmade Factors Affecting Their Continued Existence
“Small Number of Individuals and Populations,” below. Additionally, we added the fragile tree snail under the section titled “Small Number of Individuals and Populations,” below, as it was noted in Table 3, but missing from the discussion under Factor E.
(14) Due to a comment from a peer reviewer, we have made a change regarding the life-cycle of Slevin's skink under Description of the 23 Mariana Islands Species, below. In the proposed rule, we cited Brown (1991, pp. 14-15) as stating that Slevin's skinks are viviparous (lay their eggs internally and give birth to live young). We have corrected this statement to reflect more recent observations indicating that Slevin's skinks are oviparous (lay eggs that mature and hatch externally) (Zug 2013, p. 184; Rodda 2014, in litt.).
(15) Due to new information received during the comment period, we have added a new occurrence for the Rota blue damselfly. Zarones (
et al.
2015b, in litt.) reported a new observation of an individual of the Rota blue damselfly, located at a stream east of the Water Cave that is not connected to the Water Cave (Okgok) Stream. This finding was confirmed by U.S. Fish and Wildlife Service (Service) entomologists. This new occurrence has been added under Description of the 23 Mariana Islands Species, below.
(16) According to new information we received during the comment period, we corrected the name of I-Chenchon Park, which is now the Mariana Crow Conservation Area; added the Sabana Heights and Talakhaya conservation areas under the Sabana Wildlife Conservation Area on Rota; and added the newly established Nightingale Reed-warbler Conservation Area and the Micronesian Megapode Conservation area to conservation areas on Saipan (see
Islands in the Mariana Archipelago,
below).
(17) After further analysis, we have concluded that feral cattle are not a threat to the plant
Heritiera longipetiolata
on the island of Tinian, nor are feral cattle considered present in large enough numbers to be assigned to the island of Tinian in Table 4, below. The humped tree snail was believed to be extirpated from Tinian at the time of the proposed rule and, therefore, was not previously assigned this threat on Tinian. Both feral and domestic cattle have been present on Tinian for centuries and have reportedly caused broad-ranging negative impacts to the forest ecosystem (
i.e.,
erosion, trampling, and grazing); however, the number of feral cattle on Tinian has declined in recent times (Wiles
et al.
1990, pp. 167-180; Flores 2015, in litt.). Cattle ranching on Tinian is on the rise, and depending on the location and amount of land allotted to cattle ranching, negative impacts to the forest ecosystem may be observed in the future. However, at the time of this final rule, neither feral nor domestic cattle
are considered a threat to the plant
Heritiera longipetiolata
or the humped tree snail on the island of Tinian.
(18) In the Regulation Promulgation section of the proposed rule, we identified the historic range of
Cycas micronesica
as Guam and the Mariana Islands. We have corrected the historic range of
Cycas micronesica
in this final rule to additionally include the sovereign island nation of the Federated States of Micronesia (the island of Yap), and the independent island nation of the Republic of Palau.
Background
Mariana Islands Species Addressed in This Final 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 the subjects of this final rule. Following the table, Figure 1 provides a map of the islands that comprise the Mariana archipelago.
Table 1—The 23 Mariana Islands Species Addressed in This Final Rule
Scientific name
Common name(s)
Listing status
Range
Plants
Bulbophyllum guamense
wild onion siboyas halumtanu
Ch
, siboyan halom tano
CI
Threatened
Guam, Rota, Saipan (H), Pagan (H).
Cycas micronesica
fadang
Ch
, faadang
CI
Threatened
Guam, Rota, Pagan
‡
, Palau *, Yap.*
Dendrobium guamense
NCN
Threatened
Guam, Rota, Saipan (H), Tinian,
Aguiguan
, Agrihan (H).
Eugenia bryanii
NCN
Endangered
Guam.
Hedyotis megalantha
pao dedu
Ch
, pao doodu
CI
Endangered
Guam.
Heritiera longipetiolata
ufa halumtanu
Ch
, ufa halom tano
CI
Endangered
Guam, Saipan, Tinian,
Rota
.
Maesa walkeri
NCN
Threatened
Guam, Rota.
Nervilia jacksoniae
NCN
Threatened
Guam, Rota.
Phyllanthus saffordii
NCN
Endangered
Guam.
Psychotria malaspinae
aplokating palaoan
Ch / CI
Endangered
Guam.
Solanum guamense
Biringenas halumtanu
Ch
, birengenas halom tano
CI
Endangered
Guam, Rota (H), Saipan (H), Tinian (H), Asuncion (H), Guguan (H), Maug (H).
Tabernaemontana rotensis
NCN
Threatened
Guam, Rota.
Tinospora homosepala
NCN
Endangered
Guam.
Tuberolabium guamense
NCN
Threatened
Guam, Rota, Tinian (H), Aguiguan (H).
Animals
Emballonura semicaudata rotensis
Pacific sheath-tailed bat (Mariana subspecies), payeyi
Ch
, paischeey
CI
Endangered
Aguiguan, Guam (H), Rota (H), Tinian (H), Saipan (H), Anatahan (H
§
), Maug (H
§
).
Emoia slevini
Slevin's skink, Marianas Emoia, Marianas skink, gualiik halumtanu
Ch
, gholuuf
CI
Endangered
Guam (H), Cocos Island, Rota (H), Tinian (H), Aguiguan (H), Sarigan, Guguan, Pagan, Alamagan, Asuncion.
Hypolimnas octocula marianensis
Mariana eight-spot butterfly, ababbang
Ch
, Libweibwogh
CI
Endangered
Guam, Saipan (H).
Vagrans egistina
Mariana wandering butterfly, ababbang
Ch
, Libweibwogh
CI
Endangered
Rota, Guam (H).
Ischnura luta
Rota blue damselfly, dulalas Luta
Ch
, dulalas Luuta
CI
Endangered
Rota.
Partula gibba
humped tree snail, akaleha
Ch
, denden
CI
Endangered
Guam, Rota, Aguiguan, Alamagan, Pagan, Sarigan, Saipan,
Tinian
, Anatahan (H).
Partula langfordi
Langford's tree snail, akaleha
Ch
, denden
CI
Endangered
Aguiguan.
Partula radiolata
Guam tree snail, akaleha
Ch
, denden
CI
Endangered
Guam.
Samoana fragilis
fragile tree snail, akaleha dogas
Ch
, denden
CI
Endangered
Guam, Rota.
NCN = no common name.
(H) = historical occurrence (20 years or more prior to present date).
(H §) = possible historical occurrence.
Ch = Chamorro name.
CI = Carolinian name.
* = range outside of the Mariana Islands.
‡ = Tentative occurrence.
Translations courtesy of the Chamorro/Carolinian Language Policy Commission.
Bold type in the Listing Status and Range columns indicates a change in range from the proposed rule.
BILLING CODE 4310-55-P
ER01OC15.080
BILLING CODE 4310-55-C
The Mariana Islands
Here we discuss only background information pertinent to the Mariana Islands that has changed since the proposed rule. Please see the proposed rule (79 FR 59364; October 1, 2014) for a description of the general geography, geology, vegetation, hydrology, climate, biogeography, and pre-historic human impact. We would like to acknowledge a spelling error in the proposed rule under “Hydrology,” where we incorrectly spelled Talofofo as Tolofofo. Talofofo is the correct spelling for this hydrological region in Guam. Additionally, we have made substantial changes from the proposed rule to the
below section, Historical and Ongoing Human Impacts, for the reasons described above in the section Summary of Changes from Proposed Rule.
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 Saipan and Tinian, and to a lesser extent on Rota, 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 United States 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; JGPO-NavFac, Pacific 2014, pp. ES-1—ES-34; JGPO-NavFac, Pacific 2015, pp. ES-1—ES-40;
http://guambuildupeis.us/
). 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) (JGPO-NavFac, Pacific 2014, p. ES-3) and Final SEIS (JGPO-NavFac, Pacific 2015, pp. ES-1—ES-40;
http://guambuildupeis.us/
); (2) the development of facilities and infrastructure (
i.e.,
cantonment, family housing, and associated infrastructure) on Guam to support the relocation of military personnel and their dependents (JGPO-NavFac, Pacific 2015, p. ES-3;
http://guambuildupeis.us/
); and (3) the development and construction of facilities and infrastructure on Guam to support training and operations for the relocated Marines, specifically a Live-Fire Training Range Complex (LFTRC) (JGPO-NavFac, Pacific 2015, p. ES-3;
http://guambuildupeis.us/
)
The Final 2015 SEIS focuses on changes to the proposed actions and alternatives identified in the 2010 Final EIS (JGPO-NavFac, Pacific 2014, p. ES-1) and 2014 Draft SEIS (JGPO-NavFac, Pacific 2015, pp. ES-1—ES-40;
http://guambuildupeis.us/
). The preferred alternative sites on Guam for the implementation of the Marine relocation efforts and development of an LFTRC now include Alternative E Finegayan (Navy Base Guam)-Andersen Air Force Base (AFB) and Alternative 5 Northwest Field on Andersen AFB, respectively. Alternative E is a new alternative not presented in the 2014 Draft SEIS. The 2014 Draft SEIS had listed Alternative A Finegayan as the preferred alternative for cantonment and housing, and the new preferred Alternative E places the cantonment on Finegayan and family housing on Andersen AFB. This new Alternative E was added to reduce the amount of vegetation that would have to be cleared, present additional opportunities for forest enhancement mitigation, maintain the natural buffer area between developed areas and nearby sensitive coastal resources (
e.g.,
Haputo Ecological Reserve Area), and leverage existing family housing support facilities already in place at Andersen AFB (JGPO-NavFac, Pacific 2015, p. ES-15;
http://guambuildupeis.us/
). Finegayan and Northwest Field on Andersen AFB collectively support 16 of the 23 species or their habitats (11 of the 14 plants:
Bulbophyllum guamense, Cycas micronesica, Dendrobium guamense, Eugenia bryanii, Heritiera longipetiolata, Maesa walkeri, Nervilia jacksoniae, 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) (JGPO-NavFac, Pacific 2014, pp. ES-18—ES-22; JGPO-NavFac, Pacific 2015, p. ES-11;
http://guambuildupeis.us/
).
The Final SEIS describes: (1) More moderate construction activity over 13 years instead of a 7-year intense construction boom; (2) a significant reduction in projected peak population increase (from 79,000 to less than 10,000) and steady state population increase (from 33,000 to approximately 7,400); (3) a reduction in the project area at Finegayan from 2,580 ac (1,044 ha) to 1,213 ac (491 ha); (4) utilization of 510 ac (206 ha) of existing infrastructure on Andersen AFB for family housing; (5) no new land acquisition; (6) a reduction in project area at Northwest Field (instead of Route 15); and (7) an overall decrease in power and water demands (JGPO-NavFac, Pacific 2014, p. ES-3; JGPO-NavFac, Pacific 2015, p. ES-11;
http://guambuildupeis.us/
).
Concurrent with the relocation efforts discussed above, the U.S. Marine Corps (the Executive Agent designated by the U.S. Pacific Command) published their “Commonwealth of the Northern Mariana Islands (CNMI) Joint Military Training (CJMT) Draft Environmental Impact Statement (EIS)-Overseas Environmental Impact Statement (OEIS)” (herein referred to as the “CJMT Draft EIS-OEIS”) (CNMI Joint Military Training Draft EIS-OEIS at
http://www.cnmijointmilitarytrainingeis.com/about
). The 2015 Draft CJMT EIS-OEIS informs the public that the military has proposed plans to use Tinian and Pagan to establish a series of live-fire range training areas, training courses, and maneuver areas to reduce existing joint service training deficiencies and meet the U.S. Pacific Command Service Components' unfilled unit level and combined level training requirements in the Pacific (2015 CNMI Joint Military Training Draft EIS-OEIS at
http://www.cnmijointmilitarytrainingeis.com/about
).
The northern two-thirds of Tinian are leased to the Department of Defense (DOD), and the development of these lands will negatively impact the habitat of 2 of the 23 species addressed in this final rule, the plant
Heritiera longipetiolata,
and the humped tree snail. Likewise, live-fire training on Tinian will negatively impact the habitat and individuals of
H. longipetiolata
and the humped tree snail. On Pagan, both Alternative 1 and Alternative 2 claim the entire island for training purposes, with the north dedicated to live-fire maneuver areas, and the south dedicated to non-live-fire maneuver areas (CJMT Draft EIS-OEIS
http://www.cnmijointmilitarytrainingeis.com/about
). If the entire island of Pagan is used for training purposes, it will negatively impact 2 of the 16 species listed as endangered species in this final rule, Slevin's skink and the humped tree snail, and their habitats. Additionally,
Cycas micronesica
may be present on Pagan, although this is not yet confirmed. If
Cycas micronesica
is confirmed on Pagan, then this species would be considered negatively impacted by ordnance and live-fire training on both Guam and Pagan.
Additionally the entire Mariana archipelago is located within the Mariana Islands Training and Testing (MITT) Study Area, which comprises air, land, and sea space, and includes the existing Mariana Islands Range Complex (MIRC), its surrounding seas, and a transit corridor between the MIRC and the Navy's Hawaii Range Complex, where training and testing activities may occur. The MIRC is the only Navy range complex in the MITT Study Area (JGPO-NavFac, Pacific 2013, pp. 1-3; Mariana Islands Training and Testing
http://mitt-eis.com/EISOEIS/Background.aspx
). The MITT Study Area opens up every island within the Mariana Archipelago as a potential training site (
Mariana Islands Training and Testing
http://mitt-eis.com/EISOEIS/Background.aspx
), which subsequently may result in negative impacts to any number of the 23 species addressed in this final rule. Proposed actions include increases in training activities on Guam, Rota, Saipan, Tinian, Farallon de Medinilla (increase in bombing), and Pagan. Likely negative impacts include, but are not limited to, direct damage to individuals from live-fire training and ordnance, wildfire resulting from live-fire and ordnance, direct physical damage (
e.g.,
trampling by humans, helicopter landing, etc.) to individuals, and spread of nonnative species. Additionally, water purification training is proposed for all of these islands, except Farallon de Medinilla, which may be particularly damaging to the Rota blue damselfly, for which the only known location exists along the freshwater streams of the Talakhaya watershed.
In addition to military spending, Guam's economy depends on tourism. More than one 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 in the 70s and 80s. Also at this time, the growth of a private economy occurred, fueled by tourism (Guampedia
http://www.guampedia.com/evolution-of-the-tourism-industry-on-guam-2/
, Accessed April 23, 2015). Currently, tourism accounts for about 60 percent of Guam's annual business revenue and 30 percent of all non-Federal jobs (Guam Visitor Bureau 2014, p. 3;
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).
An increase in human population, whether from tourism or a military presence, also increases the type and intensity of stressors on endangered and threatened species. These stressors range from increased development, which results in loss of habitat, to increased risk for introduction of harmful nonnative species, which directly or indirectly impact native species and their habitats. As Guam is seeking a “no visa required” status for visitors from Russia and China (Guam Visitor Bureau 2014, p. 33), monitoring of sea ports and airports against inadvertent introduction of harmful and invasive species is especially important (see “
Factor D. The Inadequacy of Existing Regulatory Mechanisms”
). The proposed increase in military training activities throughout the Marianas heightens the importance for enhanced monitoring at these sites.
Political Division
Micronesia is made up of six island groups: (1) Mariana Islands; (2) Caroline Islands, consisting of the sovereign island nation of the Federated States of Micronesia (Yap, Chuuk, Pohnpei, and Kosrae) and the independent island nation of the Republic of Palau; (3) Gilbert Islands (politically the Republic of Kiribati); (4) Marshall Islands (politically the Republic of the Marshall Islands); (5) Nauru (politically the Republic of Nauru, the world's smallest republic, consisting of a single phosphate rock island); and (6) Wake Island (also known as Wake Atoll, an unorganized, unincorporated territory of the United States). Micronesia, together with Polynesia, is described as the “Polynesia-Micronesia Hotspot,” reflecting the fact 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. 853-858) (see Summary of Biological Status and Threats Affecting the 23 Mariana Islands Species, below).
Islands in the Mariana Archipelago
Please see the proposed rule (79 FR 59364; October 1, 2014) for a description of each of the 14 Mariana Islands; a map of the islands is included here as Figure 1. The below island descriptions are included in this final rule because they include at least one substantial change since publication of the proposed rule. These sections reflect new information received during the two comment periods on the proposed rule.
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 180 m) above sea level interrupted by a few low hills, of which two (Mataguac and Mt. Santa Rosa) are volcanic in nature, while 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 at Agana Swamp
located in the middle of the island. Guam is also the most populated of all the Mariana Islands, with an estimated 170,000 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 Human Impact,” 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 last remaining intact native habitats and subsequently some of the last remaining individuals of the rarest species. There are three conservation areas on the island 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 final rule occur on Guam (all 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 5 of the 9 animals: Slevin's skink (Cocos Island, off Guam), the Mariana eight-spot butterfly, the Guam tree snail, the humped tree snail, and the fragile tree snail. The Pacific sheath-tailed bat (Mariana subspecies) and the Mariana wandering butterfly 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
2
) (96 square kilometers (km
2
)) in land area (Mueller-Dombois and Fosberg 1998, p. 265; CNMI Statewide Assessment and Resource Strategy Council (CNMI-SWARS) 2010, p. 6). The highest point on the island is Mount Sabana (also referred to as the Sabana plateau or simply the Sabana), 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 listed as threatened species in this final 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
et al.
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 (DLNR): (1) The Sabana Wildlife Conservation Area (which includes the Sabana Heights Conservation Area and the Talakhaya Conservation Area); (2) Mariana Crow Conservation Area and Bird Sanctuary; and (3) Wedding Cake 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 final rule currently occur on Rota (8 of the 14 plants:
Bulbophyllum guamense, Cycas micronesica, Dendrobium guamense, Heritiera longipetiolata
(recently rediscovered; formerly thought extirpated from Rota),
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 plant
Solanum guamense,
and the Pacific sheath-tailed bat (Mariana subspecies), 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
2
(18 km
2
) 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. Four of the 23 species addressed in this final rule occur on Aguiguan: the plant
Dendrobium guamense
(recently discovered for the first time on Aguiguan); and the Pacific sheath-tailed bat (Mariana subspecies), 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
2
(101 km
2
) 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 over 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). There are two small wetland areas, heavily overgrown with no open water, Hagoi Marsh and Marpo Swamp, which 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), predominantly along the southeastern portion of Tinian (Spaulding 2013, in litt.; Spaulding 2015, in litt.). Tinian supports the forest and cave ecosystems. Tinian currently has no designated conservation areas. Three of the 23
species addressed in this final rule occurs on Tinian, the plants
Dendrobium guamense
and
Heritiera longipetiolata
and the humped tree snail (recently rediscovered; formerly thought extirpated from Tinian). The plants
Solanum guamense
and
Tuberolabium guamense
and the Pacific sheath-tailed bat (Mariana subspecies) 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
2
(115 km
2
) 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 the CNMI Division of Forestry has suggested it forms a unique mixed forest habitat on Saipan not reported from the other islands (CNMI-SWARS 2010, p. 7). There are six conservation areas on Saipan: (1) Bird Island Wildlife Conservation Area; (2) Kagman Wildlife Conservation Area and Forbidden Island Sanctuary; (3) Marpi Commonwealth Forest; (4) Nightingale Reed-Warbler Conservation Area; (5) Micronesian Megapode Conservation Area; and (6) 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 final rule occurs on Saipan, the humped tree snail. The plants
Bulbophyllum guamense, Dendrobium guamense,
and
Solanum guamense,
the Pacific sheath-tailed bat (Mariana subspecies), and the Mariana eight-spot butterfly were known from Saipan historically.
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
2
(48 km
2
) (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. Two of the 23 species are known to occur on Pagan, the animals Slevin's skink and the humped tree snail. The tree
Cycas micronesica
also likely occurs on Pagan; however, this is not yet confirmed (see
Cycas micronesica
under Description of the 23 Mariana Islands Species, below). The plant
Bulbophyllum guamense
occurred historically on Pagan.
The descriptions for each of the remaining northern islands in the Mariana Archipelago remain unchanged from the proposed rule and, therefore, are not included in this final rule. Please refer to the proposed rule (79 FR 59364; October 1, 2014) for further information.
An Ecosystem-Based Approach to Organizing This Listing Rule
In the Mariana Islands, as within most archipelagos, native species that occur in the same habitat types (ecosystems) depend on many of the same biological features and the successful functioning of that ecosystem to survive. We have, therefore, organized the species addressed in this final rule by common ecosystems. Although the listing determination for each species is analyzed separately, we have organized the individual analysis for each species within the context of the broader ecosystem in which it occurs for efficiency and to reduce repetition for the reader. In addition, native species that share ecosystems often face a suite of common factors that may be a threat to them, and ameliorating or eliminating these threats for each individual species often requires the same management actions in the same areas. Cost-effective management of these threats often requires implementation of conservation actions at the ecosystem level to enhance or restore critical ecological processes and provide long-term viability of species and their habitat. Organizing the 23 Mariana Islands species by shared ecosystems may also set 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.
Based on the best available scientific and commercial data, including information received during the comment period on our proposed rule (79 FR 59364; October 1, 2014), we are listing the plants
Eugenia bryanii, Hedyotis megalantha, Heritiera longipetiolata, Phyllanthus saffordii, Psychotria malaspinae, Solanum guamense,
and
Tinospora homosepala;
and the animals Pacific sheath-tailed bat (Mariana subspecies), Slevin's skink, Mariana eight-spot butterfly, Mariana wandering butterfly, Rota blue damselfly, humped tree snail, Langford's tree snail, Guam tree snail, and fragile tree snail from the Mariana Islands, as endangered species. We are listing the plants
Bulbophyllum guamense, Cycas micronesica, Dendrobium guamense, Maesa walkeri, Nervilia jacksoniae, Tabernaemontana rotensis,
and
Tuberolabium guamense,
from the Mariana Islands and greater Micronesia, as threatened species.
These 23 Mariana Islands species are found in four ecosystem types: Forest, savanna, stream, and cave (Table 2). Of the 23 species, only the Pacific sheath-tailed bat (Mariana subspecies) 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
Pacific sheath-tailed bat (Mariana subspecies).
Cycas micronesica
Slevin's skink.
Dendrobium guamense
Mariana eight-spot butterfly.
Eugenia bryanii
Mariana wandering butterfly.
Heritiera longipetiolata
Humped tree snail.
Maesa walkeri
Langford's tree snail.
Nervilia jacksoniae
Guam tree snail.
Psychotria malaspinae
Fragile tree snail.
Solanum guamense
Tabernaemontana rotensis
Tinospora homosepala
Tuberolabium guamense
Savanna
Hedyotis megalantha
Phyllanthus saffordii
Stream
Rota blue damselfly.
Cave
Pacific sheath-tailed bat (Mariana subspecies).
For each species, we identified and evaluated those factors that are threats to each individual species specifically (species-specific threats), as well as those factors which pose 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 listed as endangered or threatened in this final rule. We have labeled such threats that are shared by all species within the same ecosystem as “ecosystem-level threats,” because they impact all species inhabiting 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, and not shared by all other species in the same ecosystem. For example, the threat of predation by nonnative flatworms is unique and specific to the four tree snails addressed in this final rule.
Mariana Islands Ecosystems
As noted above, for the purposes of organizing our threats discussion for the 23 species by shared habitats, we have identified 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; and the proposed rule (79 FR 59364; October 1, 2014)). 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 listed as endangered or threatened species in this final rule. These four ecosystems are described in the proposed rule (79 FR 59364; October 1, 2014) and these descriptions are hereby incorporated into this final rule, with the exception of a revised description of the forest ecosystem, below; see Table 2 (above) for a list of the species that occur in each ecosystem type.
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). There are multiple plant species 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, Cyanometra ramiflora,
Elaeocarpus joga, Ficus prolixa,
Hernandia labyrinthica, H. sonora,
Merrilliodendron megacarpum, Ochrosia mariannensis,
O. oppositifolia, 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,
Allophylus timoriensis, Eugenia palumbis,
E. reinwardtiana, Hibiscus tiliaceus,
Maytenus thompsonii, Meiogyne cylindrocarpa,
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 such that it receives and retains 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, or occur on one or more of the northern islands. 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, p. 243). 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 (Falanruw
et al.
1989, p. 8; 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, precipitation, and associated native canopy, subcanopy, and understory species, listed above. The forest ecosystem supports 20 of the 23 species listed as endangered or threatened species in this final rule (all except the plants
Hedyotis megalantha
and
Phyllanthus saffordii,
which occur only in the savanna ecosystem, and the Rota blue damselfly, which occurs only in the stream ecosystem).
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 (as indicated, for example, by the presence of individuals representing multiple life-history stages). 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
(siboyas halumtanu, siboyan halom tano), 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;
Zarones
et al.
2015c, in litt.).
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, there are 12 known occurrences (3 on Guam and 9 on Rota) totaling fewer than 250 individuals on Guam and at least 261 individuals on Rota. At the time of the proposed rule, our information indicated that there were likely fewer than 30 individuals of this species on Rota. However, a recent survey team on Rota reported at least 261 individuals of
B. guamense
along the Sabana tableland and slopes above 980 ft (300 m) elevation with a population structure consisting of seedlings, juveniles, and flowering adults. This survey team estimated the overall number of individuals could be as high as 16,000. This latter estimate appears to be an assumption based on the premise that
B. guamense
is uniformly distributed across the region in preferred habitat areas (Zarones
et al.
2015c, in litt.).
The Service does not concur that there are enough data to determine that this species is uniformly distributed across the Sabana, and subsequently cannot support the extrapolation of numbers for this species to be as high as 16,000, although it is possible. The healthy population structure of
B. guamense
recently observed on Rota, with multiple generations of plants present, does show that the status of this species is better on this island than previously understood. Historically, there are a couple of herbarium records of
B. guamense
occurring on Pagan (last observed in 1984) and Saipan (last observed in 1970), however, these are considered outliers and not within the accepted endemic range of
B. guamense.
Due to the common occurrence of errors detected throughout the herbaria records and literature, the Service recognizes Guam and Rota as the most scientifically credible range for this species.
Bulbophyllum guamense
has declined in number of populations and individuals on Guam, which represents half of its known range, and the species exists in a specialized niche habitat within the forest ecosystem on 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. We anticipate the effects of climate change will further exacerbate many of these threats in the future.
Cycas micronesica
(fadang, faadang), a cycad in the cycad family (Cycadaceae), is known from Guam, Rota, and tentatively on 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
A. yasumatsui
(see “
Factor C. Disease and Predation,”
below for further discussion) (Marler and Muniappan 2006, p. 3; Marler and Lawrence 2012, p. 233; Western Pacific Tropical Research Center 2012, p. 4; Marler 2013, pers. comm.).
Currently, there are 15 to 20 occurrences of
Cycas micronesica
totaling 900,000 to 950,000 individuals on the Micronesian Islands of Guam, Rota, Yap, and Palau. There may be a small number of individuals on Pagan; however, this is not yet confirmed. 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
Cycas circinalis
in a ravine on the southwest part of the island. Cycas
micronesica
was once merged with
C. rumphii
or
C. circinalis,
but is now considered a separate species (Hill 1994, pp. 543-567; Hill
et al
2004, p. 280). It is more likely that this cycad species on Pagan is
C. micronesica;
however, until identification is confirmed, we consider this a tentative location.
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
2
(102 km
2
). 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
2
(458 km
2
). On Palau, there are four occurrences of
C. micronesica
totaling fewer than 2,500 individuals: (1) Two occurrences on Ngeruktabel Island, totaling fewer than 900 individuals, (2) one occurrence on Ngesomel Island totaling 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.).
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, and direct damage and destruction by military live-fire training is large, and these threats are imminent. We anticipate the effects of climate change will further exacerbate many of these threats in the future. 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, pp. 239—240) 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. Marler and Lawrence's data show that it is reasonable to conclude that, unless an effective biocontrol is discovered, the scale will similarly impact the three populations of
C. micronesica
in the Rock Islands of Palau within several years. Additionally, frequent travel between Guam and Yap increases the likelihood that the scale will reach Yap in the foreseeable future.
Dendrobium guamense
(no common name (NCN)), an epiphyte and occasional lithophyte in the orchid family (Orchidaceae), is known from the forest ecosystem on Guam, Rota, Saipan (historically), and Tinian, and was recently recorded for the first time on Aguiguan (Ames 1914, p. 14; Raulerson and Rinehart 1992, p. 98; Quinata 1994, in litt.; Raulerson 2006, in litt.; Costion and Lorence 2012, p. 66; Zarones
et al.
2015a, in litt.; Zarones
et al.
2015c, in litt.). Raulerson (2006, in litt.) cites
D. guamense
as also occurring on Agrihan, however, a voucher record or survey report to support this location could not be found. 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 (Raulerson and Rinehart 1992, p. 98; Consortium Pacific Herbarium (CPH) 2012a—
Online Herbarium Database,
5 pp.).
Currently, there are at least 21 occurrences totaling approximately 1,250 individuals distributed on the islands of Guam, Rota, Tinian, and Aguiguan; this is more than twice as many individuals as were known at the time of the proposed rule. On Guam, there are 4 occurrences totaling fewer than 250 individuals (Quinata
et al.
1994, p. 8; Harrington
et al.
2012, in litt). On Rota, at least 15 occurrences of
D. guamense
are now known, and a recent survey team reported more than 700 individuals of
D. guamense
on the western third of Rota, represented by seedlings, juveniles, and flowering adults (Harrington
et al.
2012, in litt.; Zarones
et al.
2015c, in litt.). The presence of multiple generations in a healthy population structure indicates that the status of
D. guamense
on Rota is better than previously known. This survey team indicated that
D. guamense
is abundant across its preferred habitat on Rota, and subsequently suggested that the actual number of individuals could be as high as 35,000 (Zarones
et al.
2015c, in litt.). The Service supports the finding that the number of
D. guamense
individuals on Rota is in the thousands, although we do not agree that it is reasonable to assume the species is evenly distributed across the island. However, this species is the most abundant of the three epiphytic orchids listed as threatened species in this final rule.
Additionally, Zarones
et al.
(2015a, in litt.) discovered three individuals of
D. guamense
on the island of Aguiguan, a new island record for this species. Zarones
et al.
(2015a, in litt.) hypothesize that more individuals may be found on Aguiguan and other northern islands within CNMI if more in-depth surveys were attempted. There are two reported occurrences on the island of Tinian, with an unknown number of individuals (Quinata 1994, in litt.; Raulerson 2006, in litt.; CPH 2012a—
Online Herbarium Database,
5 pp.). Historically,
D. guamense
was also known from Saipan, in the forest ecosystem (Raulerson 1987, in litt.; Raulerson 2006, in litt.; CPH 2012a—
Online Herbarium Database,
5 pp.). Formerly relatively common on Guam, the remaining few populations of
D. guamense
and habitat for population enhancement or restoration on Guam is at risk; additionally,
D. guamense
occurrences are limited to just a few individuals on Tinian and Aguiguan, with no confirmed individuals on Saipan at this time.
Dendrobium guamense
appears stable and healthy on Rota, however, Raulerson and Rinehart (1992, p. 87) warned that, although the endemic orchids on Rota appear abundant, they occupy specialized habitat that are in fact rare.
On all islands on which it is known to occur (historically or present),
D. guamense
faces two or more of the following impacts: Habitat loss and destruction from agriculture, urban
development, nonnative animals and plants, fire, and typhoons, combined with herbivory by nonnative invertebrates such as slugs. We anticipate the effects of climate change will further exacerbate many of these threats in the future.
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. We anticipate the effects of climate change will further exacerbate many of these threats in the future.
Hedyotis megalantha
(pao dedu, pao doodu), 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 or herbarium errors 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—
Online 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. We anticipate the effects of climate change will further exacerbate many of these threats in the future.
Heritiera longipetiolata
(ufa halumtanu, ufa halom tano; 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;
Global Biodiversity Information Facility (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 no known remaining individuals on Rota at that time (Wiles in International Union for Conservation of Nature (IUCN) Red List 2014, in litt.). Currently,
H. longipetiolata
is known from 10 occurrences totaling approximately 200 individuals, on Guam, Saipan, Tinian, and Rota, 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 Guam,
H. longipetiolata
is presently known from 4 occurrences, totaling approximately 90 individuals; on Tinian, there are between 30 and 40 individuals of
H. longipetiolata,
and possibly more in adjacent forested areas (Spaulding 2013, in litt.; Williams 2013, in litt.; Spaulding 2015, in litt.); on Saipan,
H. longipetiolata
is known from 3 occurrences, totaling at least 53 individuals, with several hundred seedlings beneath the trees (Camacho and Micronesian Environmental Services (MES) 2002, pp. 38-39); and on Rota, more recent information indicates that there is at least one known individual of
H. longipetiolata
(Cook 2010, in litt. cited in CNMI-DLNR 2015, in litt.).
Although Wiles stated that there is strong evidence that
H. longipetiolata
is not regenerating, and that seedlings and seeds are eaten by ungulates and crabs, this observation appears to have been made on Guam where feral deer and feral pigs are abundant and have been observed to eat seedlings of
H. longipetiolata
(Guam Comprehensive Wildlife Conservation Strategy 2005, p. 117; Rogers 2012, in litt.; 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. With roughly 200 individuals remaining across its range (Guam, Saipan, Tinian, and Rota), both
Heritiera longipetiolata
and habitat for the recovery of this species are at risk due to ongoing habitat loss and destruction from agriculture, urban development, nonnative animals and plants, and typhoons. We anticipate the effects of climate change will further exacerbate many of these threats in the future. Herbivory by pigs and deer, and habitat and direct destruction by military live-fire training also negatively impact
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; M and E Pacific, Inc. 1998, pp. 31, 79; Raulerson and Rinehart 1991, p. 67; 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 5 occurrences in the forest ecosystem on Guam and Rota, totaling at least 686 individuals. This is a significant increase over numbers of individuals that were known at the time
of the proposed rule (estimated at fewer than 60). On Guam, there are two individuals (M and E Pacific, Inc. 1998, pp. 31, 79; Grimm 2013, in litt.); and on Rota, there are at least 684 individuals spread out across the Sabana, with a healthy population structure consisting of seedlings, juveniles, and adults (Harrington
et al.
2012, in litt.; Gawel 2013, in litt.; Liske-Clark
et al.
2015, in litt.). The presence of multiple generations of the species indicates that the status of
M. walkeri
is much better on Rota than previously understood. The number of individual
Maesa walkeri
plants on Rota has been estimated to be in the thousands across the Sabana region in small canopy gaps amidst the Pandanus forest and along the forest edge; however, this is assuming
M. walkeri
is evenly distributed (Ulloa 2015, pers. comm. cited in Liske-Clark
et al.
2015, in litt.; Liske-Clark
et al.
2015, in litt.).
The Service supports the conclusion that there may be several thousand more individuals across the Sabana. The cumulative data indicate that
Maesa walkeri
was once relatively abundant on Guam and Rota, and has since declined substantially on Guam. The only healthy extant population of
M. walkeri
remains on the Rota Sabana within a very specialized niche habitat that is experiencing habitat loss and degradation from nonnative animals (deer and rats) and plants, and fire; and is at risk from impacts associated with typhoons and future climate change (
e.g.,
potential shift in range to accommodate changes in temperature, precipitation, humidity, etc., until the range no longer exists). Additionally, habitat on Guam that is essential for the recovery of
M. walkeri
continues to be affected by ongoing habitat loss and destruction from agriculture, urban development, nonnative animals and plants, fires, and typhoons. The effects of future climate change will likely exacerbate many of these impacts.
Maesa walkeri
is a species of concern for Guam's Plant Extinction Prevention Program.
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 southern Guam and on the Sabana region 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.; Zarones
et al.
2015d, 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.; Zarones
et al.
2015d, in litt.).
Zarones
et al.
(2015d, in litt.) recently conducted a small survey on Rota, reporting 167 individuals of
N. jacksoniae
along four transects in just 1.5 hours, and estimated that there may be as many as 100,000 individuals distributed across the Pandanus forest on the Rota Sabana. This estimate, however, appears to be based on the premise that this species is uniformly distributed across area. There are also a few scattered occurrences along the areas adjacent to the Sabana (Zarones
et al.
2015d, in litt.). Our records indicate that this species occurs in a more patchy distribution, in specialized niche habitat (Harrington
et al.
2015, in litt.). Similarly, Falanruw
et al.
(1989, pp. 6-7) noted variation in the distribution of native species across the Sabana, referring to the observed variations in forest structure as phases of limestone forest. However, we do concur that the number of
N. jacksoniae
individuals is likely to be much higher than what has been observed by field biologists on Rota in the past, as this species can occur deep within forested areas in the Sabana region that are difficult to access due to extremely rugged karst and thick
Pandanus
forest. Thus, although exact numbers are not known, the best available scientific data do indicate that
N. jacksoniae
is likely more abundant than was understood at the time of the proposed rule. Nonetheless, the habitat for
N. jacksoniae
in the Sabana region is experiencing habitat destruction and modification by nonnative animals (
i.e.,
Philippine deer and rats) and plants, fire, and typhoons. Additionally,
N. jacksoniae
is preyed upon by nonnative invertebrates such as slugs.
Data indicate that populations of
N. jacksoniae
are decreasing from their initial abundance observed on Guam (Rinehart and Fosberg 1991, p. 84; Cook 2012, in litt.; Harrington
et al.
2012, in litt.), primarily due to habitat loss and destruction from agriculture and urban development; in addition to nonnative animals (
i.e.,
pigs, water buffalo, Philippine deer, and brown treesnake) and plants, fires, and typhoons, and predation by nonnative invertebrates such as slugs. We anticipate the effects of climate change will further exacerbate many of these threats in the future.
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—Agriculture 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.). Populations of
P. saffordii,
a single island endemic, are thus 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. We anticipate the effects of climate change will further exacerbate many of these threats in the future.
Psychotria malaspinae
(aplokating 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 northeast and southwest 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 four occurrences, three with only a single individual each (M and E Pacific, Inc. 1998, pp. 67, 79; Grimm 2012, in litt.), none of which
have been observed for at least 5 years; and a fourth recently discovered occurrence with three individuals (Guam Plant Extinction Prevention Program 2015, in litt.). Biologists searched for this species during rare plant surveys conducted in July 2012; however, none of the occurrences reported prior to July 2012 were relocated (Harrington
et al.
2012, in litt.). The tentative specimen of
P. malaspinae
collected from the Ritidian National Wildlife Refuge on Guam in August 2013, cited in the proposed rule as pending identification, turned out to be
P. hombroniana
—another rare endemic species that may warrant conservation actions (Gawel
et al.
2013, in litt.; Gawel 2015, in litt.).
Psychotria malaspinae
is also a species of concern for Guam's Plant Extinction Prevention Program.
In summary, the species
Psychotria malaspinae,
a single island endemic, has been reduced to an estimated five individuals in the wild, and possibly fewer since several of these individuals have not been observed for several years, rendering this species vulnerable to extinction. There are likely a few scattered individuals or small occurrences such as that recently discovered; however, these remaining individuals are at risk, due to continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, and typhoons. We anticipate the effects of climate change will further exacerbate many of these threats in the future. Herbivory by pigs and deer, damage by ordnance and live-fire training, 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
(Biringenas halumtanu, birengenas halom tano), 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 highly vulnerable to extinction, as there is only one known extant individual of this species. There is a possibility that remaining individuals of
S. guamense
may occur on Asuncion, Guguan, or Maug; or any combination of these three islands, possibly even on Uracas, as these four islands are designated Wildlife Conservation Areas (also referred to as sanctuary islands) by the CNMI constitution (Article IX[2]) (Williams
et al.
2009, p. 3). This article states that no hunting, habitation, nor introduction of any nonnative species is allowed (2NMIAC § 85-30.1 330) (Williams
et al.
2009, p. 3). Further, Maug, Asuncion, Guguan, and Uracas are not frequently visited for scientific purposes due to their remoteness and the associated logistical challenges of planning and cost.
Solanum guamense,
and habitat for its recovery on Guam, Rota, Saipan, and Tinian, are at risk, due to continued habitat loss and destruction from agriculture, urban development, nonnative animals and plants, and typhoons. We anticipate the effects of climate change will further exacerbate many of these threats in the future. 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. We originally proposed to list
T. rotensis
in January of 2004 (69 FR 1560, January 9, 2004); however, in April 2004 (69 FR 18499) we declined to do so because an authoritative monographic work on the genus incorporated this species into 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 (69 FR 1560; January 9, 2004). In 2007, more than 21,000 individuals were found throughout Andersen AFB on Guam, with a population structure representing seedling, juveniles, and reproductive, mature individuals (UOG 2007 p. 4). In 2014, the CNMI DLNR completed a survey of all known locations of naturally occurring and outplanted individuals of
T. rotensis
on Rota, and found nine living naturally occurring individuals and one dead individual (CNMI DLNR 2014, in litt.). These were spread across the western, southern, and eastern parts of the island. Additionally, there are 30 surviving outplanted individuals, ranging in size from 4 to 23 ft (1.3 to 7 m), spread out across the island (J. Manglona, T. Reyes, R. Ulloa, pers. comm. 2014 cited in CNMI DLNR 2014, in litt.). Therefore, the best scientific data currently available indicate that 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), and on Rota,
T. rotensis
is known from 9 individuals (CNMI DLNR 2014, in litt.).
Despite the increased number of known individuals of
Tabernaemontana rotensis,
populations of this species 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 ordnance and live-fire training. We anticipate the effects of climate change will further exacerbate many of these threats in the future. The greatest concern regarding this species is not of population size or structure, but the close proximity of occurrences to an area that is likely to be developed according to the proposed AFB and Navy base expansions (UOG 2007, p. 5; JGPO-NavFac Pacific 2010a, 2010b; JGPO-NavFac Pacific 2014; JGPO-NavFac Pacific 2015;
http://guambuildupeis.us/
).
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
(Forman 1981, pp. 381, 417, and 419; Costion and Lorence 2012, p. 93).
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. Though Forman (1981, p. 419) notes that if fruits of
T. homosepala
are discovered and they are indistinguishable from
T. glabra,
it may be preferable to reduce
T. homosepala
to subspecific rank under
T. glabra.
It should also be noted that 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. We anticipate the effects of climate change will further exacerbate many of these threats in the future.
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 as there is not a single voucher that cites the Cook Islands as a collection site (CPH 2012f—
Online Herbarium Database;
GBIF 2012f—
Online 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 database
).
Currently,
T. guamense
is known from seven occurrences: one occurrence of one individual on Guam and six occurrences on Rota, in the forest ecosystem (Gawel
et al.
2013, in litt.; Harrington
et al.
2012, in litt.; Zarones
et al.
2015c, in litt.). It is possible that a few more individuals are scattered across native forests on Guam. The number of occurrences on Rota represents an increase over those known at the time of the proposed rule. A recent survey on Rota (Zarones
et al.
2015c, in litt.) reported finding 239 individuals of
Tuberolabium guamense
along 6 of 18 transects surveyed on the Sabana, with a healthy population structure consisting of seedlings, juveniles, and flowering adults. Zarones
et al.
(2015c, in litt.) estimate that the actual number of
T. guamense
individuals on the Sabana may be as high as 14,600; however, this appears to assume that
T. guamense
is evenly distributed across the Sabana region. The Service does not concur that this species is evenly or uniformly distributed across the Sabana, consequently we conclude that 14,600 individuals is likely an overestimate. For example, a particularly noteworthy observation from these recent surveys is that
T. guamense
seems to occur solely in native canopy trees, with the majority of individuals found on
Hernandia labyrinthica, Premna obtusifolia,
and
Elaeocarpus joga
(Zarones
et al.
2015c, in litt.). As these native canopy trees are not distributed uniformly across the landscape, neither would we expect
T. guamense
to be evenly or continuously distributed across the Sabana. However, we do agree that the survey results of Zarones
et al.
(2015c, in litt.) indicate that the species
Tuberolabium guamense
is currently more abundant on Rota than previously known.
In summary, populations of
Tuberolabium guamense
are decreasing from their initial abundance observed on Guam, and although new data show a higher number of
T. guamense
individuals than previously thought on Rota,
T. guamense
still occupies very specialized niche habitat in the Sabana region. More than 20 years ago, Raulerson and Rinehart (1992, p. 87) stated that although the orchids may appear abundant on the limestone ridges of Guam and Rota, “the habitats are limited and in reality these orchids are very rare.” Additionally, they wrote, “The islands are small and habitats are rapidly being destroyed by human activity” (Raulerson and Rinehart 1992, p. 87). Although numbers of
T. guamense
are estimated to be possibly in the thousands on Rota (Zarones
et al.
2015c, in litt.), because of the specialized niche habitat occupied by this species we are not in full agreement with this estimate, which relies on an assumption of uniform distribution. Furthermore, habitat for the recovery of this species is considered at risk across its range. The remaining 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, typhoons, and herbivory by slugs. We anticipate the effects of climate change will further exacerbate many of these threats in the future.
Animals
Pacific Sheath-Tailed Bat (Mariana Subspecies)
The Mariana subspecies of the Pacific sheath-tailed bat (
Emballonura semicaudata rotensis
) (payeyi, paischeey) is a small, insectivorous (insect-feeding), sac-winged bat in the family
Emballonuridae,
an old-world group with an extensive tropical distribution. It is a relatively small bat species with an approximate forearm length of about 1.8 in (45 mm) long. Males weigh 0.2 ounces (oz.) (5.5 grams (g)) on average, and females weigh about 0.24 oz. (6.9 g) (Wiles
et al.
2011, p. 303). The pelage varies in color from brown to dark brown dorsally with a paler underbody (Walker and Paradiso 1983, p. 211). The common name “sheath-tailed” bat refers to the nature of the tail attachment, which involves a short, narrow tail emerging from a more anterior sheath-like membrane (Walker and Paradiso 1983, p. 209).
Taxonomically, four subspecies of Pacific sheath-tailed bats are currently recognized:
Emballonura semicaudata rotensis,
endemic to the Mariana Islands (Guam and the CNMI, referred to here as the Mariana subspecies);
E. s. sulcata
in Chuuk and Pohnpei (Pohnpei subspecies);
E. s. palauensis
in Palau (Palau subspecies); and
E. s. semicaudata
in American and Independent Samoa, Tonga, Fiji, and Vanuatu (South Pacific subspecies) (Koopman 1997, pp. 358-360; Oyler-McCance
et al.
2013, pp. 1,030-1,036). Recent genetic analysis conducted by Oyler-McCance
et al.
(2013, p. 1,030) found notable genetic differences between
E. s. rotensis, E. s. palauensis,
and
E. s. semicaudata;
the magnitude of these differences was greater than what is typically reported between
mammalian subspecies. In addition to divergence from the other three subspecies, which would argue against reintroduction efforts based on translocations of individuals between subspecific localities, the study found no genetic variation between the 12
E. s. rotensis
individuals collected and examined (Oyler-McCance
et al.,
2013, p. 1,035), which increases the risks associated with small number of individuals and populations.
Once common and widespread throughout Polynesia and Micronesia, the Pacific sheath-tailed bat, represented by the four subspecies, is the only insectivorous bat recorded from a large part of this area (Hutson
et al.
2001, p. 138; Gorresen
et al.
2009, p. 331; Wiles
et al..
2011, p. 299; Oyler-McCance
et al.
2013, p. 1,030; Valdez
et al.
2013, p. 301). In the Caroline Islands, large numbers of individuals of the sheath-tailed bat subspecies
Emballonura semicaudata palauensis
were readily observed by Wiles
et al.
during studies in the 1990s (1997, p. 224). However, the other three subspecies of the bat have declined dramatically, including in 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). In American Samoa, a decrease in populations of the sheath-tailed bat subspecies
E. s. semicaudata
was noted as early as the 1970s (Grant
et al.
1994, pp. 133-134). Researchers have identified several possible factors for the past and ongoing decline of the Pacific sheath-tailed bat throughout its range, including human disturbance of caves for guano mining and shelter during World War II, bombing and shelling during World War II, indiscriminate use of pesticides, predation by monitor lizards, rats, and brown treesnakes, increasingly isolated populations, and loss of foraging habitat due to human conversion and destruction and alteration by typhoons and nonnative plants and animals (Gorresen
et al.
2009, p. 339; Valdez
et al.
2011, p. 302; Wiles
et al.
2011, pp. 306-307; and Oyler-McCance
et al.
2013, p. 1,035).
In the Mariana Islands, fossil evidence indicates the Mariana subspecies (
Emballonura semicaudata rotensis
) (hereafter simply referred to as the Pacific sheath-tailed bat or simply “bat,” unless noted otherwise), was common on both Guam and Rota, and somewhat less common on the island of Tinian (Steadman 1999, p. 321; Wiles and Worthington 2002, pp. 1-3; Wiles
et al.
2011, p. 299). Historically, populations of the Pacific sheath-tailed bat were reported from Saipan (Wiles
et al.
2011, p. 299), and possibly on Anatahan and Maug as well (Lemke 1986, pp. 743-745). The Mariana subspecies of the Pacific sheath-tailed bat is now restricted to a single remaining population on the small (2.7 square-mile (sq mi; 7 square-kilometer (sq km)) island of Aguiguan, where it was first observed in 1984 (Wiles
et al.
2011, p. 299). The bat has clearly experienced a precipitous reduction from its wider historical range in the Mariana Islands (formerly Guam, Rota, Saipan, Tinian, and Aguiguan), which can reasonably be assumed to be coincident with a significant decline in abundance of individuals.
Currently, the Aguiguan bat population consists of several roosting colonies 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; Wiles
et al.
2011, p. 299; Oyler-McCance
et al.
2013, p. 1,030). During several field surveys between 1995 and 2008, Wiles
et al.
(2011, pp. 299-305), examined a total of 114 caves on the island, of which approximately 8 caves contained roosting bats, with 4 caves consistently occupied during the 13-year study period. Colonies ranged in size from 333 bats in the largest colony, to between 1 and 64 one bats in the other colonies (Wiles
et al.
2011, pp. 301-303).
Despite observed declines in populations of most Pacific sheath-tailed bat subspecies elsewhere, as well as with the Marianas subspecies in general across the Marianas Archipelago, researchers have recorded a small increase in the observed number of bats on Aguiguan in past years, starting with 98 individuals in 1995, up to 285 to 364 bats in 2003, and 359 to 466 bats in 2008 (Wiles
et al.
2011, p. 304). The researchers used population growth models to ensure that this apparent increase is biologically plausible, as opposed to a potential artifact of variable survey methods; they conclude that the increase is most likely real, while cautioning that additional data and analysis are needed. They also suggest that the single remaining population of the Mariana subspecies of Pacific sheath-tailed bat on Aguiguan is more likely limited by foraging habitat, and not by roosting habitat (Wiles
et al.
2011, pp. 304-305). Although this very small population on the tiny island of Aguiguan appears to be relatively healthy, it has limited foraging habitat, which is threatened by feral goats, nonnative plants, development, and typhoons; and the bats are at risk from predation by rats, monitor lizards, and brown treesnakes.
Breeding of Pacific sheath-tailed bats is timed to coincide with offspring born during the onset of the rainy season when there are predictably greater numbers of insect prey. Pacific sheath-tailed bat females produce one pup per litter annually, which translates into relatively low fecundity for the species (Wiles
et al.
2011, p. 303). The bats are nocturnal and roost during the day in a wide range of cave-types, including overhanging cliffs, limestone solution caves, crevices, and lava tubes, (Grant
et al.
1994, pp. 134-135; O'Shea and Valdez 2009, pp. 105-108), and emerge shortly before sunset to forage on insects (Craig
et al.
1993, p. 51; Wiles and Worthington 2002, p. 13; Wiles
et al.
2011, pp. 301-303). Unlike the Pohnpei subspecies, which utilizes hollow trees for roosting (Wiles
et al.
2011, p. 305), the Mariana subspecies of the Pacific sheath-tailed bat appears to be cave-dependent on Aguiguan, which has approximately 114 caves of various sizes classified from small to large (Wiles
et al.
2011, pp. 301-302). On the Northern Mariana Islands, which contain far fewer caves due to their relatively young geologic age and volcanic origin, it is possible that the presence of the predatory monitor lizard may preclude the use of hollow trees as roosting sites by the Pacific sheath-tailed bat (Wiles 2011, p. 306).
The Pacific sheath-tailed bat is also known to share roosting caves with Mariana swiftlets (birds,
Aerodramus
spp.) (Lemke 1986, pp. 744-745; Tarburton 2002, pp. 106-107; and Wiles and Worthington 2002, pp. 7, 13; Wiles
et al.
2011, p. 302). During several field studies between 1995 and 2008, Wiles
et al.
(2011, pp. 302-303), observed Mariana swiftlets roosting in seven out of eight caves co-occupied by the bat, albeit within somewhat segregated portions of the cave. In the same 1995-2008 study, Wiles
et al.
(2011, p. 302) also determined that bats on Aguiguan prefer caves characterized as “large” (over 1,076 ft
2
(100 m
2
) in floor area with ceiling heights reaching 16 to 98 ft (5 to 30 m)) (see “Cave Ecosystem,” in the proposed rule (79 FR 59364; October 1, 2014), for further cave description). Researchers also found occupied caves to be fairly constant in both temperature and humidity, with conditions homogenous and consistent between occupied caves, including most seemingly suitable, unoccupied caves (Wiles
et al.
2011, p. 305).
Some information about the Pacific sheath-tailed bat's biology and life history, including reproduction, habitat use, diet, and limiting factors, has been historically difficult to observe and collect due to a variety of factors
including the bat's small size, secretive habits, difficulty of capture, non-specific roosting sites, and—following its extirpation from most of the islands in its range in the Marianas—the remoteness of the sole remaining population (Wiles and Worthington 2002, p. 19; Esselstyn
et al.
2004, p. 304; Wiles
et al.
2011, p. 305). Funded by the Department of the Navy and the Service, more recent studies including Gorresen
et al.
2009 (pp. 331-340), O'Shea and Valdez 2009 (pp. 95-97), Valdez
et al.
2011 (pp. 301-309), Wiles
et al.
2011 (pp. 299-309), and Oyler-McCance
et al.
2013 (pp. 1,030-1,036), have provided us with new information about the species. For example, we now know from fecal pellets collected from caves on Aguiguan that Pacific sheath-tailed bats there consume a diverse array of small-sized (0.078-0.314 in (2-8 mm)) insects, including ants, bees, and wasps (Hymenoptera), moths (Lepidoptera), and beetles (Coleoptera), as their primary prey (O'Shea and Valdez 2009, pp. 63-65; Valdez
et al.
2011, pp. 301-307).
Earlier surveys of habitat use on Aguiguan in 2003 revealed that the Pacific sheath-tailed bat forages almost entirely in native and nonnative forests near their roosting caves, ignoring non-forested habitats on the island (Esselstyn
et al.
2004, p. 307). Outside of the Mariana Islands, Bruner and Pratt (1979, p. 3) observed similar behavior, with the other subspecies of Pacific sheath-tailed bats (
Emballonura semicaudata semicaudata, E. s. sulcata,
and
E. s. palauensis
) foraging only in native forests. New evidence from recent studies appears to confirm prior observations regarding the association between bat foraging and native limestone forest. For example, the aforementioned dietary study by Valdez
et al.
2011 (pp. 301-307), showed that the bat feeds on certain insects, including barklice (Pscoptera) and fungus-feeding beetles, each very specific to forest habitat on Aguiguan. A 2008 study analyzed the bat's specific method of echolocation (use of sonar to navigate) and flight pattern, both of which are similar to other insect-eating, forest-foraging bats, to identify a correlation between foraging activity and roosting site proximity to native forest canopy and the height and nature of that forest canopy (O'Shea and Valdez 2009, pp. 105-108; Gorresen
et al.
2009, p. 331). The Gorresen
et al.
study (2009, p. 336) as well as Wiles
et al.
(2011 p. 305), point to the high number of unoccupied caves on Aguiguan and suggest it is likely the amount of native forest cover, not the number of suitable roost sites, that may be the main factor currently limiting the island's Pacific sheath-tailed bat population. Some researchers go further to point out that insectivorous bats relying on forested areas for foraging are at greater risk of extinction than those which employ a wider range of foraging methods (Gorresen
et al.
2009, p. 339). Researchers familiar with the status of the Pacific sheath-tailed bat readily identify an almost complete lack of native forest regeneration on Aguiguan and the ever-present possibility of forest destruction by hurricanes as two factors threatening the species' continued existence in the Mariana Islands (Gorresen
et al.
2009, p. 339; Wiles
et al.
2011, pp. 306-307).
In summary, the Mariana subspecies of the Pacific sheath-tailed bat (
Emballonura semicaudata rotensis
), now reduced to a single, remaining population on Aguiguan, has shown a clear and significant decline from its original wide range across at least four, and possibly as many as six, of the Mariana Islands. With recent research suggesting inter-genetic homogeneity within its own population, we now understand that the Mariana Islands Pacific sheath-tailed bat is at especially great risk due to its small population size and isolation from other subspecies. Despite the small increases in abundance of the sole remaining population noted in recent years, the Mariana subspecies of the Pacific sheath-tailed bat faces threats of continued habitat loss and destruction. Additionally, predation by monitor lizards, and potential predation by the brown treesnake, may contribute to the further decline of the species.
Slevin's Skink
Slevin's skink (
Emoia slevini,
gualiik halumtanu, ghóluuf) 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 Division of Fish and Wildlife (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 Guam, where it was recently rediscovered (Fritts and Rodda 1993, p. 2; Steadman 1999; Lardner 2013, in litt.). Local skink experts hypothesize that the individuals on Cocos Island may be a distinct species or subspecies from Slevin's skinks in the northern islands, and are currently conducting a genetic analysis to determine the taxonomic status (Reed 2015, in litt.).
Surveys conducted in the 1980s and 1990s show that Slevin's skink was once present on the northern islands of Sarigan, Guguan, Alamagan, Pagan, and Asuncion (Vogt 1997, in litt.; Berger
et al.
2005, pp. 174-175; GDAWR 2006, p. 107); however, none were captured on Anatahan or Agrihan or ever reported historically from these islands (Rodda
et al.
1991, p. 202; Berger
et al.
2005, p. 175). 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 (Fritts and Rodda 1993, p. 1; Rodda 2002, pp. 1-3). The most recent surveys of Alamagan were completed in 2000. Based on their survey efforts, Cruz
et al.
(2000, pp. 24, 26) reported a capture rate of approximately 0.019 Slevin's skinks per trap hour for Alamagan, which was lower than the capture rate of 0.033 per trap hour reported by McCoid
et al.
(1995, as cited in Cruz
et al.
2000, p. 24) 5 years earlier. The authors state that this may be indicative of a decline in the population of Slevin's skink on the island, but also note that it may be due to seasonal fluctuations (sampling was limited to only 2 nights at a single location in June 2000); they conclude that more surveys are needed (Cruz
et al.
2000, p. 26).
After the eradication of feral ungulates from the island of Sarigan in 1998, the catch rate of skinks (number of lizards captured per hour) roughly quadrupled in a survey conducted in 2007 (Vogt 2007, p. 5-5; Kessler 2011, p. 322), which indicates the skinks are doing much better on Sarigan and that ungulates played a role in their prior decline. Numbers of Slevin's skinks trapped on Asuncion in surveys conducted in 2008 were quite low; only 3 individuals were captured following 350 hours of effort at 20 trap stations, translating to 0.008 per trap hour (Williams
et al.
2008, pp. 36). Recent intensive surveys on Pagan conducted in 2010 by Reed
et al.
(2010, pp. 22, 27) found no Slevin's skinks, leading some experts to postulate that Slevin's skink may be potentially extirpated on Pagan,
if not certainly rare, but ultimately concluding that it is too early to make a definitive judgment (Rodda 2014, in litt.). The current status of Slevin's skink on Guguan 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 is active during the day. 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; Cruz
et al.
2000, p. 21; GDAWR 2006, p. 107; 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 are oviparous, with a normal clutch size of two (Zug 2013, p. 184; Rodda 2014, in litt.). Other specific life-history or habitat requirements of Slevin's skink are not well documented (Rodda 2002, p. 3; Zug 2013, p. 184).
Slevin's skink was most numerous in the Mariana Islands 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). Likewise, as noted above, the observed four-fold increase in captures of Slevin's skink on Sarigan following the removal of nonnative ungulates from that island (Vogt 2007, p. 5-5; Kessler 2011, p. 322) indicates that nonnative ungulates have a negative impact on the species. Slevin's skink had not been recorded on Guam since 1945 and had not been observed 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 (following eradication of rats from that island; Campbell 2011, pers. comm.). Over half of Cocos 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 for Slevin's skink is available on Cocos Island, and this is periodically overwashed during typhoons (Fritts and Rodda 1993, pp. 2, 5), thus there is little if any stable suitable habitat permanently available on the island.
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, provided the great majority of its formerly occupied range, totaling an estimated 179,900 ac (72,800 ha). Even without considering its potential recent extirpation from Pagan, based on these numbers it is apparent that Slevin's skink has likely been reduced to just 10 percent of its overall historical range, and its remaining suitable habitat is a subset of that area.
In summary, once widespread, the remaining known populations of Slevin's skink are made up of a few individuals on Cocos Island, where habitat is limited and subject to overwashing, and occurrences of undetermined numbers of individuals on Alamagan, Guguan, Sarigan, and Asuncion. Slevin's skink persists in low numbers observed on Cocos Island, is possibly extirpated from Pagan, and has not been reobserved on Guam, Rota, Tinian, or Aguiguan. Of the nine islands from which it was formerly known, Slevin's skink is known to be recovering to some degree from the effects of past threats (nonnative ungulates) only on the island of Sarigan; however, other threats remain on this island (
e.g.,
rats). Overall, Slevin's skink has been lost from 90 percent of its former range. Because populations are reduced in distribution and likely small, we conclude the remaining populations of Slevin's skink are at risk, due to continued habitat loss and destruction from agriculture, development, nonnative animals (feral pigs, cows, and goats), and typhoons. We anticipate the effects of future climate change will further exacerbate many of these threats in the future. Predation by rats, monitor lizards, and possible predation by the brown treesnake (if the snake is introduced to other islands), also pose ongoing threats to Slevin's skink.
Mariana Eight-Spot Butterfly
The Mariana eight-spot butterfly (
Hypolimnas octocula marianensis
) (abbabang, libweibwogh), 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
and
H. anomala
(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 (Schreiner and Nafus 1996, p. 1; Rubinoff 2013, in litt.). Surveys show that these two host plants are no longer observed in places where nonnative ungulates can reach them easily, and in the rare case that a plant grows long enough to extend beyond the protection of the extremely rugged limestone karst, browsing damage is observed (Rubinoff 2013, in litt.; Lindstrom and Benedict 2014, pp. 29, 32-35; Rubinoff 2014, in litt.). The eradication of ungulates would allow these host plants to expand their range onto less rugged karst, consequently increasing their availability for the Mariana eight-spot butterfly. When adult butterflies were observed, they were always in proximity to the host plants (Rubinoff 2011, in litt.; Rubinoff 2013, p. 1). 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.).
Recent surveys conducted across Guam confirmed the occurrence of the Mariana eight-spot butterfly in six areas on the island (Lindstrom and Benedict 2014, p. 9). This survey report did not provide estimates for the number of individuals per population. Lindstrom and Benedict (2014, p. 9) stated that there are currently only 6 populations of this species, not the 11 populations cited in the October 1, 2014, proposed rule (79 FR 59364). We do not believe this difference reflects a reduction in the number of populations since the publication of the proposed rule, however. In part, this discrepancy in numbers may lie in the definition of a “current population.” We distinguish populations as separate if they are 3,280 ft (1,000 m) or more apart, and define
current
as a report within 20 years from the present date. In addition, although quite extensive, the surveys conducted by Lindstrom and Benedict and colleagues (2014, pp. 1-44) did not survey all previously cited current occurrences for the Mariana eight-spot butterfly on Guam (Schreiner and Nafus 1996, p. 2; Schreiner and Nafus 1997, p. 26; Rubinoff 2011, in litt.; Rubinoff and Haines 2012, in litt.; Rubinoff 2013, in litt.), so some may have been overlooked. Finally, a lack of observation on select transects at previously reported sites does not necessarily translate to a complete absence of the species at that location; the lack of observation may be more indicative that the species exists in very low numbers. Especially if the site is visited only once, it is easy to miss an observation if individuals are quite rare.
On Saipan, several areas were found that supported host plants in 2011 and 2012; however, no individuals of the Mariana eight-spot butterfly were seen, and it may be extirpated on Saipan (Schreiner and Nafus 1997, p. 26; Harrington
et al.
2012, in litt., p. 19; Rubinoff 2014, in litt.). It is possible that small undetected populations of the Mariana eight-spot butterfly still occur on islands previously recorded (Lindstrom and Benedict 2014, p. 34), or even on the more isolated northern islands on which it has not previously been recorded (Rubinoff 2014, in litt.); however, without any evidence, this remains postulation.
In summary, the Mariana eight-spot butterfly is now found in only six populations on the island of Guam. This butterfly is dependent upon two relatively rare host plant 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. We anticipate the effects of climate change will further exacerbate many of these threats in the future. 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
) (abbabang, libweibwogh) 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.
Schreiner 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).
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., 2008, pp. 1-9). Despite extensive surveys on Guam in 2013 for the Mariana wandering butterfly and several other candidate species, no evidence (
i.e.,
egg, larva, or adult) of the Mariana wandering butterfly was found (Lindstrom and Benedict 2014, pp. 21-41).
Although considered extirpated from Guam, whether the Mariana wandering butterfly continues to exist on Rota is unknown, since the island has not been surveyed specifically for this butterfly since 1995. It is possible this species occurs on the northern islands where host plants are found (Rubinoff 2014, in litt.), although there is no record of its presence. Several years of seasonal surveys are needed to determine the status of this species, but 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. We anticipate the effects of climate change will further exacerbate many of these threats in the future. 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
) (dulalas Luta, dulalas Luuta) 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 been observed in association only 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 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 (Camacho
et al.
1997, p. 4; Polhemus
et al.
2000, pp. 1-8). 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 spring water 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 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,” in the proposed rule (79 FR 59364; October 1, 2014), and Water Extraction under
Factor E. Other Natural or Manmade Factors Affecting Their Continued Existence,
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.). This is 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. In November 2015, Zarones
et al.
(2015b, in litt.) conducted a survey on Rota looking for the Rota blue damselfly and found one individual along a stream 744 yards (680 m) to the west of Water Cave area, not connected to the stream at the Water Cave. Zarones
et al.
(2015b, in litt.) did not report whether or not any native or nonnative fish were observed in the stream.
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 abundant only 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 (Talakhaya watershed area) 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 future climate change, could eliminate one of the only two known populations of the species (see “Stream Ecosystem,” in the proposed rule (79 FR 59364; October 1, 2014), and Water Extraction under
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 results in loss of vigor and genetic representation, and contributes to the vulnerability of the single known population of the Rota blue damselfly.
Humped Tree Snail
The humped tree snail (
Partula gibba;
akaleha, denden), in the Partulidae family, is endemic to the forest ecosystem on the Mariana Islands of Guam, Rota, Saipan, Tinian, Aguiguan, 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), Tinian (NavFac, Pacific 2014, pp. 5-5—5-7), 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 relocated on a survey by Smith in 2006 (Smith 2013, p. 14). This species 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, with evenly spaced spiral sculpturing (Cowie 2014, in litt.). The color ranges from white to brown, and a pointed apex is 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 4.5 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 may live up to 5 years. They reproduce in less than 1 year, at which time they can produce up to 18 young each year. Partulids are ovoviviparous (give birth to live young), more mobile during higher ambient humidity and precipitation and less mobile during dry periods, live on bushes or trees, and feed primarily on dead or decaying plant material (Cowie 1992, p. 167; Hopper 2014, in litt.).
The humped tree snail occurs in cool, shaded forest habitat as first observed by Crampton (Crampton 1925, pp. 31, 61), with high humidity and reduced air movement that prevents excessive water loss. Crampton (1925, pp. 31, 61) described the habitat requirements of the partulid tree 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 tree snails 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. Although tree snails in the Mariana Islands likely evolved to live upon native vegetation, there is no clear indication of obligate relationships with any particular type of tree or plant (Fiedler 2014, in litt.). Further, Mariana partulid snail species are observed to use nonnative “home plants” to which they have apparently adapted (Fiedler 2014, in litt.). Although it has been suggested that native crabs may prey on Mariana partulid snails (Fiedler 2014, in litt.), they are not regarded as a major threat to these tree snails compared to alien carnivorous flatworms (
i.e.,
the manokwari flatworm) and snails (
i.e.,
the rosy wolf snail
Euglandina rosea
and
Gonaxis
spp.) (Cowie 1992, p. 175). Nonnative mites and ants have also raised some concerns about their impacts on Mariana partulid snails (Fiedler 2014, in litt.); however, these are only potential threats at this time.
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. In 2009, the number of individuals of the humped tree snail on Guam was thought to have declined from hundreds to fewer than 50 individuals (Smith
et al.
2009, p. 11); however, in 2014, a previously undocumented population consisting of approximately 100 individuals was discovered (Fiedler 2014, in litt.; Myounghee Noh and Associates 2014, pp. 1-28, and Appendices A and B), which brings the total number of confirmed individuals on Guam to fewer than 150.
Bauman (1996, pp. 15, 18) surveyed Rota and reported finding live humped tree snails at 5 out of 25 former sites. 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.), thus we conclude this population is no longer extant since its suitable habitat at this site was removed. Four other populations on Rota in 2007 were small and totaled fewer than 600 individuals, collectively. Crampton was unable to visit Tinian, although he states that tree snails were known from that island (Crampton 1925, p. 6). Smith reported finding only very old shells on two surveys (2006 and 2008) of Tinian (Smith 2013, p. 6). The humped tree snail was thought to be extirpated from Tinian, until a recent survey located a single colony in a very isolated spot on the island (NavFac 2014, pp. 5-5—5-7).
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 observed at four locations on Aguiguan (Craig and Chandran 1992, p. 8; Smith 1995, pp. 13-14), but by 2008, no live snails were found on this island (Smith 2013, p. 14). 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, p. 321). Kurozumi also reported 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 have declined on Alamagan by more than 70 percent for individuals and approximately 27 percent for populations since that time (Kurozumi 1994, pp. 115-116). The humped tree snail was first reported from Pagan by Kondo in 1949 (Easley 1970, p. 87). Populations persist on Pagan, although declines similar to those on Alamagan have been observed (Kurozumi 1994, pp. 115-116).
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. The effects of future climate change are likely to have negative
impacts on the habitat of the humped tree snail, and further exacerbate other threats to the species, such as threats from typhoons to small, isolated populations. The populations on Sarigan may be relatively more stable due to the removal of ungulates (see “Conservation Efforts to Reduce Habitat Destruction, Modification, or Curtailment of Its Range,” below), but predation by rats remains a threat on that island (Kessler 2011, p. 320), as does the potential introduction of other harmful nonnative species (Hopper 2014, in litt.). Collecting of snail shells for trade may also contribute to the decline of the humped tree snail (USFWS 2012, in litt.).
Preliminary new data, soon to be published but still under review, suggest that the individuals identified as humped tree snails on Rota may be a different species (Hadfield 2010, pp. 20-21; Sischo and Hadfield 2015, under review). The species description for this newly identified partulid on Rota, tentatively named
Partula lutaensis,
will be published in a separate paper currently being drafted (Sischo 2015, in litt.). However, we must make our determination based on the best scientific data available, and at this point in time the humped tree snail is recognized as a single species. Our determination is that the humped tree snail, as currently described, warrants listing as an endangered species. If taxonomic changes are made in the future, we may reevaluate the status of any newly recognized species or subspecies at that point in time.
Langford's Tree Snail
Langford's tree snail (
Partula langfordi;
akaleha, denden), 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 remai
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