Endangered and Threatened Wildlife and Plants; Revised Designation of Critical Habitat for the Western Distinct Population Segment of the Yellow-Billed Cuckoo

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R8- ES-2013-0011; 4500030114]

RIN 1018-AZ44

Endangered and Threatened Wildlife and Plants; Revised Designation of Critical Habitat for the Western Distinct Population Segment of the Yellow-Billed Cuckoo

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Proposed rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), revise the proposed critical habitat for the western distinct population segment of the yellow-billed cuckoo (western yellow-billed cuckoo) (

Coccyzus americanus

) under the Endangered Species Act. In total, approximately 493,665 acres (199,779 hectares) are now being proposed for designation as critical habitat in Arizona, California, Colorado, Idaho, New Mexico, Texas, and Utah. If we finalize this rule as proposed, it would extend the Act's protections to this species' critical habitat.

DATES:

We will accept comments on the revised proposed rule that are received or postmarked on or before April 27, 2020. Comments submitted electronically using the Federal eRulemaking Portal (see

ADDRESSES

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

FOR FURTHER INFORMATION CONTACT

by April 13, 2020.

ADDRESSES:

You may submit comments on the revised proposed rule or draft economic analysis by one of the following methods:

(1)

Electronically:

Go to the Federal eRulemaking Portal:

http://www.regulations.gov.

In the Search box, enter Docket No. FWS-R8-ES-2013-0011, which is the docket number for this rulemaking. Then, in the Search panel on the left side of the screen, under the Document Type heading, click on the Proposed Rules link to locate this document. You may submit a comment by clicking on “Comment Now!”

(2)

By hard copy:

Submit by U.S. mail or hand-delivery to: Public Comments Processing, Attn: FWS-R8-ES-2013-0011; U.S. Fish and Wildlife Service Headquarters, MS: JAO 1/N, 5275 Leesburg Pike, Falls Church, VA 22041-3803.

We request that you send comments only by the methods described above. We will post all comments on

http://www.regulations.gov.

This generally means that we will post any personal information you provide us (see the Information Requested section below for more information).

The coordinates or plot points or both from which the critical habitat maps are generated will be included in the decisional record materials for this rulemaking and are available at

http://www.regulations.gov

at Docket No. FWS-R8-ES-2013-0011, and at the Sacramento Fish and Wildlife Office at

http://www.fws.gov/sacramento

(see

FOR FURTHER INFORMATION CONTACT

). Any additional tools or supporting information that we may develop for this critical habitat designation will also be available at the U.S. Fish and Wildlife Service website and field office set out above, and may also be included in the preamble of this rule or at

http://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT:

Jennifer Norris, Field Supervisor, U.S. Fish and Wildlife Service, Sacramento Fish and Wildlife Office, 2800 Cottage Way, Room W-2605, Sacramento, California 95825; or by telephone 916-414-6600. If you use a telecommunications device for the deaf (TDD), call the Federal Relay Service (FRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

Scope of this rule.

The information presented in this revised proposed rule pertains only to the western distinct population segment of the yellow-billed cuckoo (western yellow-billed cuckoo) (DPS). Any reference to the “species” within this document only applies to the DPS and not to the yellow-billed cuckoo as a whole unless specifically expressed. A complete description of the DPS and area associated with the DPS is contained in the proposed and final listing rules for the western yellow-billed cuckoo published in the

Federal Register

(78 FR 61621; October 3, 2013, and 79 FR 59992; October 3, 2014).

Why we need to publish a rule.

Under the Endangered Species Act, any species that is determined to be an endangered or threatened species requires critical habitat to be designated, to the maximum extent prudent and determinable. Designations and revisions of critical habitat can only be completed by issuing a rule. On October 3, 2014, we finalized listing the western yellow-billed cuckoo as a threatened species (79 FR 59992). A proposed critical habitat designation was published in the

Federal Register

on August 15, 2014 (79 FR 48548). Based on information received from Federal, State, or local government agencies, Tribal entities, and the public, and our review of our previous proposed rule, we have determined to revise our previous proposal, and to propose, as discussed herein, that approximately 493,665 acres (ac) (199,779 hectares (ha)) should be designated as critical habitat for the western yellow-billed cuckoo.

The critical habitat areas we are proposing to designate in this rule constitute our current best assessment of the areas that meet the definition of critical habitat for the western yellow-billed cuckoo. Section 4(b)(2) allows the Secretary to exclude areas if the benefits of exclusion outweigh the benefits of inclusion as critical habitat, unless, based on the best available scientific and commercial data available, that exclusion would lead to extinction. In this revised proposed designation, we have identified a total of approximately 145,710 ac (58,968 ha) that we will consider for exclusion from the final designation (see Consideration of Impacts Under Section 4(b)(2) of the Act).

What this document does.

This is a revised proposed rule to designate critical habitat for the western yellow-billed cuckoo. This revised proposed designation of critical habitat identifies areas that we propose to determine, based on the best scientific and commercial information available, are essential to the conservation of the species or otherwise essential for its conservation. The revised proposed critical habitat comprises 72 units and is located in the States of Arizona, California, Colorado, Idaho, New Mexico, Texas, and Utah.

Draft economic analysis.

In order to consider economic impacts of designating critical habitat for the western yellow-billed cuckoo, we have examined the economic information provided in the 2014 proposed rule (see Consideration of Economic Impacts, below, for additional information) and have revised that information based on a revised economic analysis for this revised proposed critical habitat designation. We are soliciting information on the economic impact of the revised proposed designation and will continue to reevaluate the potential economic impacts between our proposed and final designation. The supporting information we used in determining the economic impacts of

the revised proposed critical habitat is summarized in this rule (see Consideration of Economic Impacts) and is available at

http://www.regulations.gov

at Docket No. FWS-R8-ES-2013-0011 and at the Sacramento Fish and Wildlife Office at

http://www.fws.gov/sacramento

(see

FOR FURTHER INFORMATION CONTACT

).

Peer review.

In accordance with our peer review policy published on July 1, 1994 (59 FR 34270), we solicited expert opinions from appropriate and independent knowledgeable individuals on the August 15, 2014, proposed critical habitat rule (79 FR 48548). We received responses from four individuals with scientific expertise that included familiarity with the species, the geographic region in which the species occurs, and conservation biology principles. We reviewed the comments received from these four peer reviewers for substantive issues and new information regarding critical habitat for the western yellow-billed cuckoo. All of the peer reviewers generally concurred with our methods and conclusions and provided additional information, clarifications, and suggestions to improve the final critical habitat rule. We have incorporated some of the suggestions made by the peer reviewers into this revised proposed designation. The peer reviewer comments are available at

http://www.regulations.gov

at Docket No. FWS-R8- ES-2013-0011. We will solicit additional peer review of this revised proposed rule and respond to the peer review comments in the final rule as appropriate.

Public comment.

We are seeking comments and soliciting information from the public on our revised proposed designation to make sure we consider the best available scientific and commercial information in developing our final designation. Because we will consider all comments and information we receive during the comment period, our final determination may differ from this revised proposal. We will respond to and address comments received in our final rule. Any comments previously submitted need not be resubmitted, as they will be fully considered in preparation of the final rule.

Information Requested

We intend that any final action resulting from this revised proposed rule will be based on the best scientific and commercial data available and be as accurate and as effective as possible. Therefore, we request comments or information from other concerned governmental agencies, Native American tribes, the scientific community, industry, or any other interested parties concerning this revised proposed rule. Comments previously submitted need not be resubmitted. We will consider all comments received since the August 15, 2014, proposed designation (79 FR 48548) and respond to those comments as appropriate in the final designation of critical habitat for the western yellow-billed cuckoo. For this revised proposed designation, we particularly seek comments concerning:

(1) The western yellow-billed cuckoo's biology and range; habitat requirements for feeding, breeding, and sheltering; and the locations of any additional populations.

(2) Specific information on:

(a) The amount and distribution of western yellow-billed cuckoo habitat;

(b) Information on the physical or biological features essential for conservation of the western yellow-billed cuckoo;

(c) What areas were occupied at the time of listing that contained those features and should be included in the critical habitat designation and why;

(d) Special management considerations or protection that may be needed in areas we are proposing as critical habitat, including managing for the potential effects of climate change;

(e) What areas not occupied at the time of listing are essential for the conservation of the western yellow-billed cuckoo and should be included as critical habitat and why; and

(f) Whether the description and categorization of the habitat use by the western yellow-billed cuckoo and its physical or biological features are clear and understandable.

(3) Whether any specific areas we are proposing for critical habitat designation should be considered for exclusion under section 4(b)(2) of the Act, and whether the benefits of potentially excluding them outweigh the benefits of including them, pursuant to section 4(b)(2) of the Act. Please see the Service's policy regarding implementation of section 4(b)(2) of the Act published in the

Federal Register

on February 11, 2016 (81 FR 7226).

(4) We have received information regarding existing conservation easements or fee title purchase of private properties (conservation properties) within proposed critical habitat Units 65 and 67 (ID-1 Snake River and ID-3 Henry's Fork). These conservation properties are within the Bureau of Land Management's (BLM) Snake River Area of Critical Environmental Concern (ACEC) and Special Recreation Management Area, and have been conserved to help preserve open space, recreation opportunities, and wildlife habitat through a partnership involving the BLM, The Conservation Fund, The Teton Regional Land Trust, and The Nature Conservancy (TNC). We are looking for additional information, such as management plans or specific agreements, regarding these conservation properties that describe the commitment and assurances of protection of the physical or biological features for the western yellow-billed cuckoo to help us evaluate these areas for potential exclusion from final critical habitat designation under section 4(b)(2) of the Act. We are also looking for information regarding private land(s) in Unit 65 (ID-1) where landowners may be pursuing a conservation easement or fee title purchase in the future and have demonstrated a history of managing these lands for the conservation benefit of western yellow-billed cuckoo habitat.

(5) Whether we should exclude State-managed lands or lands with conservation easements from the designation (see Consideration of Exclusion of State Lands and Lands with Conservation Easements).

(6) Whether areas proposed to be designated as revised critical habitat along the United States/Mexico border in California, Arizona, New Mexico, and Texas should be excluded for national security and border security missions.

(7) Information on land ownership and land use designations and current or planned activities in the subject areas, and their possible impacts on the revised proposed critical habitat.

(8) Information on the projected and reasonably likely impacts of climate change on the western yellow-billed cuckoo and revised proposed critical habitat.

(9) Any probable economic, national security, or other relevant impacts of designating as critical habitat any particular area that may be included in the final designation and the benefits of including or excluding areas where these impacts occur, including,

(a) any incremental economic costs incurred to nonfederal entities for water withdrawals, such as State agencies or local municipalities as a result of the designation of critical habitat, and

(b) whether the Service should exclude lands that are part of Federal Water Resource Projects such as flood control basins, reservoirs, and channels that have been authorized by Congress to be constructed, operated and maintained for specific purposes such as flood risk reduction, navigation, hydropower from the designation where

such designation could conflict with the authorized project purposes.

(10) Suggestions of how the Service can use programmatic section 7 consultations for the western yellow-billed cuckoo to streamline the regulatory process.

(11) Whether we could improve or modify our approach to designating critical habitat in any way to provide for greater public participation and understanding, or to better accommodate public concerns and comments.

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

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

ADDRESSES

. We request that you send comments only by the methods described in

ADDRESSES

.

We will post your entire comment—including your personal identifying information—on

http://www.regulations.gov.

You may request at the top of your document that we withhold personal information such as your street address, phone number, or email address from public review; however, we cannot guarantee that we will be able to do so.

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

http://www.regulations.gov,

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

FOR FURTHER INFORMATION CONTACT

).

Previous Federal Actions

On August 15, 2014, we proposed critical habitat for the western yellow-billed cuckoo (79 FR 48548). We reopened the public comment period on November 12, 2014 (79 FR 67154), and provided notice of the public hearing held in Sacramento, California, on December 2, 2014 (79 FR 71373). All other previous Federal actions are described in the proposed and final rules to list the western yellow-billed cuckoo as a threatened species under the Act published previously in the

Federal Register

on October 3, 2013 (78 FR 61621), and October 3, 2014 (79 FR 59992). Please see those documents for actions leading to this revised proposed designation of critical habitat.

Background

The western yellow-billed cuckoo is a migratory bird species, traveling between its wintering grounds in Central and South America and its breeding grounds in North America (Continental U.S. and Mexico) each spring and fall often using river corridors as travel routes. Habitat conditions through most of the western yellow-billed cuckoo's range is often dynamic and may change location within or between years depending on vegetation growth, tree regeneration, plant maturity, stream dynamics, and sediment movement and deposition. The species' major food resources (insects) are also similarly variable in abundance and distribution. As a result, the western yellow-billed cuckoo's use of an area is tied to the area's habitat condition and food resources, which can be variable between and within years. This variability in resources may cause the western yellow-billed cuckoo to move between areas in its wintering or breeding grounds to take advantage of habitat conditions and food availability. For a thorough discussion of the western yellow-billed cuckoo's biology and natural history, including limiting factors and species resource needs, please refer to the proposed and final rules to list this species as threatened published previously in the

Federal Register

on October 3, 2013 (78 FR 61621) and October 3, 2014 (79 FR 59992) (available at

http://www.regulations.gov

at Docket No. FWS-R8-ES-2013-0104), and the proposed critical habitat rule, which published August 15, 2014 (79 FR 48548) (available at

http://www.regulations.gov

at Docket No. FWS-R8-ES-2013-0011). It is our intent to discuss below only those topics directly relevant to the revised proposed designation of critical habitat for the western yellow-billed cuckoo. Some changes made to the 2014 proposed designation were as a result of comments received from peer reviewers, Federal agencies, State agencies, Tribal entities, the public, or our review of the previous proposed designation. We have incorporated some of the suggested changes where appropriate for this proposed revision.

Ownership Mapping Considerations

The revised proposed designation of critical habitat for the western yellow-billed cuckoo encompasses a wide geographic area and extends across seven western States (AZ, CA, CO, ID, NM, TX, and UT). Obtaining current up-to-date and consistent mapping and land ownership information for such a large area is challenging. Because of this reason and requirements to use certain land ownership information under Service policy and to be as consistent as possible in mapping across the range of the species, our mapping and land ownership efforts relied on using a single land ownership ArcGIS source file to identify land ownership (Federal, State, Tribal, local, private) where it was available. In areas where this single layer was not available (

i.e.,

Texas), or more specific information was provided by the landowner, we used other (Federal, State, County, Tribal, private) land ownership information or the more specific land ownership information provided by the landowner. We have attempted to correct any land ownership identified during public comment from the previous proposed designation. However, we expect that not all land ownership may be correctly identified, and we will continue to make changes and incorporate those land ownership changes in the final designation.

Critical Habitat

Background

For additional background information on western yellow-billed cuckoo critical habitat under section 3 and section 4 of the Act, see the

Background

section in the August 15, 2014, proposed critical habitat rule (79 FR 48549-48550).

Our regulations at 50 CFR 424.12(b) outline the steps the Secretary must take in determining areas to be designated as critical habitat. In summary, these steps are to identify the geographical area occupied by the species at the time of listing, identify the physical and biological features essential to the conservation of the species, determine the specific areas within the geographical area occupied by the species that contain the physical or biological features, and then determine which of these features within those identified areas may require special management considerations or protections. The geographical area occupied by the species at the time of listing is defined at 50 CFR 424.02 as an area that may generally be delineated around species' occurrences, as determined by the Secretary (

i.e.,

range). Such areas may include those areas used throughout all or part of the species' life cycle, even if not used on a regular basis (

e.g.,

migratory corridors, seasonal habitats, and habitats used periodically, but not solely by vagrant individuals). If designating the occupied areas that meet the definition of critical habitat would be inadequate to ensure the conservation of the species, the

Secretary may designate as critical habitat unoccupied areas that meet the definition of critical habitat at 16 U.S.C. 1532(5)(A)(ii).

Occupancy Determination

The geographical area occupied at the time of listing by the western yellow-billed cuckoo DPS extends from southern British Columbia, Canada, to southern Sinaloa, Mexico, and may occur from sea level to over 7,000 feet (ft) (2,154 meters (m)) in elevation. Due to the reclusive nature of the species, the remoteness of some areas it occupies, difficulty in conducting surveys, and inconsistent survey methodology, the majority of the species' range has not been surveyed on a regular basis or have comparable survey data to give an absolute determination of population demographics, distribution, and occupancy. However, despite these survey challenges, some key areas throughout the DPS where the species is known to occur and breed more regularly, such as on the Sacramento, Kern, Verde, Colorado, San Juan, Salt, Snake, San Pedro, Gila, and Rio Grande Rivers, and several other smaller areas have been surveyed more consistently and give some indication of persistence and site fidelity. The majority of these sites are located in California and Arizona. The last statewide surveys (encompassing a large proportion of the major rivers and tributaries) for California and Arizona were conducted between 1998 and 2000 (Arizona (1998 to 1999), and California (1999 to 2000)). Therefore, we based our analysis of occupancy on detection records starting in 1998 and ending in 2014, when we listed the DPS as a threatened species. Although prior survey efforts and records of western yellow-billed cuckoo have been conducted outside California and Arizona, these efforts have been more localized or not consistent. The 1998-2014 timeframe was chosen because it includes the last statewide western yellow-billed cuckoo surveys in areas where the majority of individuals within the DPS occur and represents the best available information on long-term occupancy.

Specific Areas Outside the Geographical Area Occupied by the DPS

We are not currently proposing to designate any areas outside the geographical area occupied by the species at the time of listing because the occupied areas identified for designation provide sufficient representation of habitat (

i.e.,

ecological diversity) and redundancy (

i.e.,

the duplication and distribution of resilient populations across the range of the species allowing for the ability of a species to withstand catastrophic events) throughout the range of the DPS for the conservation of the species. All areas proposed as western yellow-billed cuckoo critical habitat are within the geographical area occupied by the DPS at the time of listing (2014) and contain the features essential to the conservation of the species. However, due to increased survey efforts since listing, we did receive some additional post-listing occupancy information for the species. We used this post-listing survey information to confirm frequency and continued occupation of certain areas, but not to identify new areas outside the geographical area occupied by the species. Based on habitat at the sites and occupancy of the species near these sites, we propose to determine occupancy of these sites to be same as at the time of listing and not new occupancy since the time of listing due to our knowledge of habitat conditions and occupancy information in surrounding areas.

Although we believe that the available evidence is sufficient for us to conclude that the units were occupied by the western yellow-billed cuckoo at the time the species was listed, for the purposes of this rulemaking, we also propose to determine that the revised proposed designation alternatively meets the definition of critical habitat in section 3(5)(A)(ii) of the Act in that the identified areas are also essential for the conservation of the species. Our rationale for this proposed determination is outlined below.

The western yellow-billed cuckoo is migratory, difficult to observe, and elusive in behavior, and chooses nesting areas based on habitat conditions and localized and variable prey outbreaks. In addition, western yellow-billed cuckoo breeding habitat is typically dynamic. For example, some breeding habitat that is not suitable one year may become suitable the next due to increased rainfall or flooding events. Other areas currently suitable and occupied may become degraded due to age or other environmental condition (

e.g.,

water availability, lack of food resource). Therefore, in our proposed determination of the extent of critical habitat, we took into account this need to accommodate the dynamic nature of existing habitat. Further, the species needs habitat areas that are arranged spatially to maintain connectivity and allow dispersal within and between units that provide for redundancy.

All of the areas that support the western yellow-billed cuckoo face threats including habitat fragmentation and degradation, altered hydrology, livestock grazing, nonnative vegetation, human disturbance, and the effects of climate change. Providing for a variety of habitat (

i.e.,

representation) primarily where the U.S. core breeding population occurs in Arizona and New Mexico (redundancy) may provide for amelioration against these threats and provide for the conservation of the species.

Therefore, given the threatened status and the relatively small number of extant western yellow-billed cuckoo breeding locations within the DPS and the need to protect the species' habitat variability and distribution, a critical habitat designation limited to areas confirmed to be occupied by breeding birds through specific surveys at the time of listing would be inadequate to provide for the conservation of the species. Accordingly, we propose to determine that the areas alternatively meet the definition of critical habitat under section 3(5)(A)(ii) of the Act, meaning that we consider these areas to be essential for the conservation of the species, as they represent the various ecological (representation) and distributional aspects (redundancy) and provide for connectivity and dispersal areas for the species when not used for breeding.

Habitat Outside the United States

Within the identified geographical area occupied at the time of listing (see Figure 2 in the final listing rule (79 FR 59999, October 3, 2014), the habitat areas used by the species are located from southern British Columbia, Canada, to southern Sinaloa, Mexico. Because we do not designate as critical habitat areas outside the United States (50 CFR 424.12(g)), we did not examine areas in Canada and Mexico; however, conservation of habitat that meets the conditions described in this designation in Canada and especially in Mexico may be important to recovery of the species. Similarly, we did not examine habitat areas on the wintering grounds in South America and the intervening areas in Central America or the Caribbean that are used as stop-over sites during migration, yet these areas may also be important for recovery of the species.

Prudency Determination

Section 4(a)(3) of the Act, as amended, and its implementing regulations (50 CFR 424.12), require that, to the maximum extent prudent and determinable, the Secretary shall designate critical habitat at the time the species is determined to be an endangered or threatened species. The regulations at 50 CFR 424.12(a)(1) state

that the Secretary may, but is not required to, determine that a designation would not be prudent in the following circumstances: (1) The species is threatened by taking or other human activity and identification of critical habitat can be expected to increase the degree of such threat to the species; (ii) The present or threatened destruction, modification, or curtailment of a species' habitat or range is not a threat to the species, or threats to the species' habitat stem solely from causes that cannot be addressed through management actions resulting from consultations under section 7(a)(2) of the Act; (iii) Areas within the jurisdiction of the United States provide no more than negligible conservation value, if any, for a species occurring primarily outside the jurisdiction of the United States; (iv) No areas meet the definition of critical habitat; or (v) The Secretary otherwise determines that designation of critical habitat would not be prudent based on the best scientific data available.

There is currently no imminent threat of take attributed to collection or vandalism identified under Factor B for this species, and identification and mapping of critical habitat is not expected to initiate any such threat. In our listing determination for the western yellow-billed cuckoo, we determined that the present or threatened destruction, modification, or curtailment of habitat or range is a threat to the western yellow-billed cuckoo and that those threats in some way can be addressed by section 7(a)(2) consultation measures. The breeding range of the species occurs largely in the jurisdiction of the United States, and we are able to identify areas that meet the definition of critical habitat. Therefore, because none of the circumstances enumerated in our regulations at 50 CFR 424.12(a)(1) has been met and because there are no other circumstances the Secretary has identified for which this designation of critical habitat would be not prudent, we have determined that the designation of critical habitat is prudent for the western yellow-billed cuckoo.

Critical Habitat Determinability

Having determined that designation is prudent under section 4(a)(3) of the Act, we must find whether critical habitat for the western yellow-billed cuckoo is determinable. Our regulations at 50 CFR 424.12(a)(2) state that critical habitat is not determinable when one or both of the following situations exist: (i) Data sufficient to perform required analyses are lacking, or (ii) The biological needs of the species are not sufficiently well known to identify any area that meets the definition of “critical habitat.” When critical habitat is not determinable, the Act allows the Service an additional year to publish a critical habitat designation (16 U.S.C. 1533(b)(6)(C)(ii)). We reviewed the available information pertaining to the biological needs of the species and habitat characteristics where this species is located. We conclude that this information is sufficient for us to conduct both the biological and economic analyses required for the critical habitat determination; that this and other information represent the best scientific data available; and that the designation of critical habitat is now determinable for the western yellow-billed cuckoo.

Conservation Strategy and Selection Criteria Used To Identify Critical Habitat

As required by section 4(b)(2) of the Act, we use the best scientific data available to designate critical habitat. In accordance with the Act and our implementing regulations at 50 CFR 424.12(b), we review available information pertaining to the habitat requirements of the species and identify specific areas to consider for designation as critical habitat. We look for areas that meet those habitat requirements (

i.e.,

contain the physical and biological features essential for the conservation of the species) within the geographical area occupied by the species at the time of listing and for any areas outside the geographical area occupied by the species that are essential for the conservation of the species.

To determine and select appropriate occupied areas that contain the physical or biological features essential to the conservation of the species or areas otherwise essential for the conservation of the western yellow-billed cuckoo, we developed a conservation strategy for the species. The goal of our conservation strategy for the western yellow-billed cuckoo is to recover the species to the point where the protections of the Act are no longer necessary. The role of critical habitat in achieving this conservation goal is to identify the specific areas within the western yellow-billed cuckoo's range that provide essential physical and biological features, without which areas range-wide resiliency, redundancy, and representation could not be achieved. This, in turn, requires an understanding of the fundamental parameters of the species' biology and ecology based on well-accepted conservation-biology and ecological principles for conserving species and their habitats, such as those described by Carroll

et al.

(1996, pp. 1-12); Meffe and Carroll (1997, pp. 347-383); Shaffer and Stein (2000, pp. 301-321); Natural Resources Conservation Service (NRCS) 2004 (entire); Tear

et al.

(2005, pp. 835-849) and Wolf

et al.

(2015, pp. 200-207); and more general riparian and avian conservation management prescriptions such as those described in Service 1985; Gardner

et al.

1999; Wyoming Partners in Flight 2002; Rich

et al.

2004; Riparian Habitat Joint Venture (RHJV) 2004; Shuford and Gardali 2008; and Griggs 2009.

Conservation Strategy

In developing our conservation strategy for determining what areas to include as critical habitat for the western yellow-billed cuckoo, we focused on the western yellow-billed cuckoo's breeding habitat. Breeding habitat includes areas for nesting and foraging and also provides for dispersal habitat when breeding or food resources may not be optimal. Breeding habitat is widely spread across the species' range and typically provides the physical and biological features essential to the conservation of the species without which range-wide resiliency, redundancy, and representation of the species could not be achieved. As explained further below, this focus led to the inclusion of breeding habitat within three general habitat settings as part of the conservation strategy. The three general settings include: (1) Large river systems (mainstem rivers and their tributaries) in the southern and central portions of New Mexico, Arizona, and along the California border with Arizona (generally referred to as the Southwest); (2) locations within southern Arizona not associated with major river systems or their tributaries; and (3) large river systems outside the Southwest (as identified in (1) above) that occur in different ecological settings that are being consistently used as breeding areas by western yellow-billed cuckoo (such as areas in parts of California, Utah, Idaho, or Colorado).

As discussed above, the western yellow-billed cuckoo is a migratory species that travels long distances to take advantage of localized food resource outbreaks or habitat availability. Maintaining breeding areas (which includes nesting habitat, foraging habitat, and dispersal habitat) throughout the range of the western yellow-billed cuckoo allows for within-year and year-to-year movements to take advantage of any spatial and temporal changes in habitat resources and food abundance. We consider this necessary to conserve the species because of the

dynamic nature of habitat used by the species. Identifying habitat across the species' range: (a) Helps maintain a robust, well-distributed population and enhances survival and productivity of the western yellow-billed cuckoo as a whole; (b) facilitates interchange of individuals between units; and (c) promotes recolonization of any sites within the current range of the species that may experience declines or local extirpations due to low productivity or temporary habitat loss or changes in resource availability; and allows for use of areas not being used as breeding as habitat for movement and dispersal.

The western yellow-billed cuckoo breeding coincides with moist and humid conditions that support abundant prey resources occurring in the temperate zones of the western United States and northern Mexico during the late spring and summer. Breeding areas of the western yellow-billed cuckoo occur primarily in riparian woodlands along perennial rivers or intermittent or ephemeral drainages containing vegetative structure, canopy cover, and appropriate environmental conditions. These areas provide suitable nesting habitat and adjacent foraging habitat with adequate food resources on a consistent basis to successfully produce and fledge young.

In general, the north-south migratory pathway of the western yellow-billed cuckoo funnels through northern Mexico into the American southwest, with a significant portion of returning birds establishing breeding territories along large river systems (mainstem rivers and their tributaries) in the southern and central portions of New Mexico, Arizona, and along the California border with Arizona. A large proportion of breeding western yellow-billed cuckoos also occur in large river systems in northwestern Mexico, primarily in Sonora and Sinaloa, with smaller numbers in Chihuahua and Western Durango, and the tip of Baja California. While returning western yellow-billed cuckoos also establish breeding territories throughout portions of the western States north of Arizona and New Mexico, these large southwestern and Mexican river systems (including but not limited to the Lower Colorado, Salt, Virgin, San Pedro, Gila, Verde, and Rio Grande Rivers) serve as core breeding habitats for the western yellow-billed cuckoo as it returns from wintering grounds in South America. These core areas together provide a consistent, robust supply of resources necessary for the maintenance and expansion of western yellow-billed cuckoos. We consider the large river systems (mainstem rivers and their tributaries) in the southern and central portions of New Mexico, Arizona, and along the California border with Arizona to be core areas for conservation of the western yellow-billed cuckoo, and they constitute the first part of our conservation strategy in determining its critical habitat. The core mainstem rivers and streams along with their major tributaries and adjacent habitats contain the physical or biological features essential for the conservation of the western yellow-billed cuckoo.

However, these managed large river systems may not provide sufficient breeding habitat for the western yellow-billed cuckoo in all years (for example, in low flow years the amount of breeding habitat along rivers is diminished), and unregulated smaller tributaries supported or influenced by monsoonal weather patterns may assist in supporting breeding western yellow-billed cuckoos during low flow or drought conditions. Thus, the second part of our conservation strategy includes areas within southern Arizona not associated with major river systems or their tributaries as identified above. In southern Arizona, western yellow-billed cuckoo also use drier habitats for breeding sites in the desert, foothill, and mountain ephemeral drainages of southern Arizona and northwestern Mexico (including but not limited to desert grasslands and scrub, and Madrean evergreen woodlands). These areas receive moisture from the seasonal North American Monsoon weather systems and other summer tropical storm events. During the breeding season, these habitats experience a “flush” of vegetation and concurrent insect population eruptions. A portion of the DPS uses these wet-seasonal or monsoonal habitats in southern Arizona and Mexico for breeding habitat. Use of these types of sites by the western yellow-billed cuckoo provides additional resiliency to the species due to the different weather patterns and hydrological regimes that produce the habitat conditions suitable for breeding. The availability of these additional resilient sites in southern Arizona and northwestern Mexico other than the large southwestern and Mexican river systems described above increases the overall redundancy for the species. Therefore, the southwestern monsoon-driven drainages with sufficient resources for western yellow-billed cuckoo foraging and successful breeding are essential for the overall resiliency and redundancy of the DPS, and is therefore essential to allow for conservation of the western yellow-billed cuckoo across its range.

Finally, while large riverine riparian systems in the core area of the American southwest are fundamentally important for their ability to contribute to the resiliency of the western yellow-billed cuckoo due to the abundance of birds in these areas, similar systems throughout the western yellow-billed cuckoo range are also likely important contributors to local resiliency and maintaining distribution of the western yellow-billed cuckoo across its range. These large river systems outside the southwest that are being consistently used as breeding areas by western yellow-billed cuckoo have been identified as the third part of our conservation strategy for determining critical habitat. These areas are located in habitats identified as being within different ecological settings, eco-types, or physio-geographic provinces and provide for additional redundancy and representation for the western yellow-billed cuckoo across its breeding range. The physical and biological features of large river systems in differing habitats with sufficient resources for western yellow-billed cuckoo foraging and successful breeding are likely important for contributing to the western yellow-billed cuckoo's overall resiliency, redundancy, and representation, and are therefore essential for conservation of the western yellow-billed cuckoo across its range. Habitats and environmental settings in the arid Southwest differ significantly from those in central California or higher elevation areas of Utah, Idaho, or Colorado. By identifying known breeding habitat of appropriate size throughout the species' range, we provide habitat where yellow-billed cuckoos are most likely to persist and potentially increase in numbers.

Selection Criteria and Methodology Used To Determine Critical Habitat

As discussed above, to assist in determining which areas to identify as critical habitat for the western yellow-billed cuckoo, we focused our selection on areas known to have breeding or suspected breeding. To do this, we selected those areas that are occupied on a continuous or nearly continuous basis each year during the breeding season. These areas were selected because they contain the physical and biological features essential to the conservation of the species necessary for western yellow-billed cuckoos to produce offspring, have ample foraging habitat, vegetative structure, environmental conditions, and prey. By selecting breeding areas as critical habitat across the western yellow-billed

cuckoo's range, we will assist in conserving the ability of the species to continue to occupy these areas. Moreover, the breeding habitat is most likely to be essential to the conservation of the species because of the importance of breeding for survival and recovery of the species.

We considered an area to be a breeding area if it was occupied by the western yellow-billed cuckoo in one of the following two ways:

• If western yellow-billed cuckoos were present in the area on one or more days between June 1 and September 30 (considered to be the primary breeding period) in at least two years between 1998 and 2014; and

• If western yellow-billed cuckoo were confirmed to be a pair and nesting (or there was evidence of nesting behavior) was observed in at least one year between 1998 and 2014, regardless of the time of year. Thus, if the mated pair or evidence of nesting behavior was discovered prior to June 1, the area was considered to be a breeding area.

In addition to these fundamental criteria established for breeding areas across the DPS range, we identified exceptions to the criteria for areas in the Southwest (Arizona and New Mexico). This was to take into account the greater contribution of the breeding areas for the DPS within the Southwest and because of the migratory nature of the species moving up from Mexico through the Southwest, either to or from other breeding areas. The exceptions to the criteria include:

• Areas in the Southwest were not considered to be breeding areas if the area contains only two western yellow-billed cuckoo records from different years, one of which was in September, and no pairs were detected. (Although western yellow-billed cuckoos are still breeding in September in Arizona, a September detection may or may not signify breeding.); and

• Areas in the Southwest were not considered to be breeding areas if western yellow-billed cuckoos previously detected during protocol surveys were absent in all subsequent visits during the same breeding season.

Another aspect of our strategy was to avoid selection of small and isolated riparian areas in the designation. Because of having limited resources, these small sites are not always occupied and typically support one to two breeding pairs but not every year. In addition, small and isolated areas are more susceptible to stochastic or catastrophic events such as flooding from major storms, prolonged drought, or wildfire. One of the goals of the conservation strategy is to include those areas that are considered core areas and contribute significantly to the overall population by producing a relatively large numbers of birds. These small isolated areas are not considered part of our conservation strategy. Although these areas may be important and assist in recovery of the species, we propose to determine that small, isolated sites with sufficient habitat for only one or two pairs of western yellow-billed cuckoos would not contribute significantly and are not essential to the conservation of the DPS and therefore not being considered as critical habitat.

As described above, to delineate the proposed units of critical habitat, we first looked to those areas being used as breeding areas. We defined what we considered breeding areas as those areas that contained seasonal occurrences of the western yellow-billed cuckoo between 1998 and 2014, at the timeframe in which breeding typically occurs for the species in the United States (June-September). In limited instances, this timeframe was expanded into May if the information available confirmed breeding activity during this earlier timeframe. These breeding occurrences (location points where breeding or breeding activity was confirmed) were then plotted on maps along with information on vegetation cover, topography, and aerial imagery. We then delineated habitat around that location, as well as riparian habitat upstream and downstream from the occurrence location.

We used reports prepared by the U.S. Geological Survey (USGS), U.S. Forest Service (USFS), National Park Service (NPS), Bureau of Land Management (BLM), Bureau of Reclamation (Reclamation), the Salt River Project, State wildlife agencies, State natural diversity data bases, Cornell Lab of Ornithology (eBird data), researchers, nongovernment organizations, universities, and consultants, as well as available information in our files, to determine the location of areas used for breeding within the geographical area occupied by the western yellow-billed cuckoo at the time of listing. As stated above, since 2014, we have become aware of additional areas occupied by the species with evidence of breeding. We still consider these areas to have been occupied by the species at the time of listing, based on habitat conditions and occupancy of nearby areas.

When delineating the critical habitat boundary, we included the surrounding contiguous suitable habitat (including along the stream course and in uplands for foraging) upstream and downstream until a break in the vegetation of 0.25 miles (mi) (0.62 kilometers (km)) or more is reached. This distance was used because the western yellow-billed cuckoo rarely traverses distances across breaks in the vegetation greater than 0.25 mi (0.62 km) in their daily foraging activities (Laymon 1980, pp. 6-8; Hughes 2015, p. 12). Upland habitat surrounding river, stream, or drainages was also included within the designation because the area is used for foraging. In some instances, we included breaks in habitat to combine one or more areas if we determined that: (1) The gap in vegetation was within minor variances of this distance; (2) the habitat on the other side of the gap was a continuation of similar or better suitable habitat and included breeding occupancy as identified above; or (3) the gap in vegetation was determined to be a consequence of natural stream dynamics essential to the continuing function of the hydrologic processes of the occupied areas. By providing breaks in habitat and combining areas, we allow for regeneration of vegetation in these areas, which is often more productive and provides additional food resources for the species and allows for appropriate habitat conditions for use when dispersing to other breeding locations.

Delineating the boundary of critical habitat was accomplished by evaluating aerial imagery, occurrence records, and vegetation information, until a break in the vegetation of 0.25 mi (0.62 km) or more was reached, at which point the upstream or downstream and lateral extent of the area was reached. In California, western yellow-billed cuckoos forage mainly within the riparian woodland habitat or directly adjacent uplands when breeding (Laymon 1980, pp. 6-8; Hughes 2015, p. 12). In New Mexico, similar foraging activity has been observed (Sechrist

et al.

2009, pp. 24-50). The foraging activity in Madrean evergreen woodland habitat (in Arizona and New Mexico) where breeding activity has also been observed has not been studied. However, based on foraging behavior in other habitats in the west, we expect the foraging distance to remain relatively close to the nesting habitat. For determining the upland extent of habitat within southwestern breeding habitat, we delineated woodland habitat in the drainage bottom and adjacent hillside. In addition, riparian corridors along streams, especially in highly developed areas, can in some instances be very narrow, highly degraded, and be characterized as a patchwork of vegetated and nonvegetated areas.

Whether these habitat areas were included or combined into a single larger unit depended on the extent of

use of the areas by western yellow-billed cuckoo, the relative amount of habitat gained if the multiple patches were included or combined, the relationship of the area to the overall designation, and the ease or complexity of removing all nonhabitat from the designation. In addition, by combining these areas, they then better meet an appropriate scale of analysis, given the data as is described in our regulations for determining critical habitat (50 CFR 424.12(b)(1)). For example, if a break in habitat occurred between an area with high occupancy with sufficient habitat and an area with low occupancy, the adjacent area may not have been included. Alternatively, if two smaller areas with relatively low occupancy were adjacent to each other, those areas most likely would have been combined to form a single, larger, more manageable area.

To distinguish between the western yellow-billed cuckoo more typical breeding habitat in riparian areas throughout the range from breeding habitat recently found in more arid areas of the Southwest, we use the terms “rangewide breeding habitat” and “southwestern breeding habitat,” respectively (see Space for Individual and Population Growth and for Normal Behavior below). In rangewide breeding habitat, we generally selected low-gradient streams containing the physical and biological features that were greater than 200 ac (81 ha)) in size. Areas smaller than 200 ac (81 ha) tend to be isolated and may contain sufficient habitat for only one or two pairs of western yellow-billed cuckoos and tend to be occupied sporadically. In considering the extent of each area, in some cases we included the entire streambed as well as the presently vegetated areas. Streams, especially those with intermittent flows, migrate within the streambed depending on flows and other natural fluvial processes. The vegetated areas within the streambed may also move to coincide with the stream movement. As a result, the whole area may not be contiguously vegetated. In these low-gradient rangewide riparian breeding habitats (

i.e.,

cottonwood, willow), areas that currently contain less than 200 ac (81 ha) of riparian habitat were not selected. However, in some areas of the Southwest, the physical or biological features for areas used as breeding habitat vary from other locations in the range of the western yellow-billed cuckoo. These areas occur in Arizona and New Mexico and are associated with summer monsoonal moisture and are smaller, narrower habitat areas that may extend into upland areas (areas dominated by mesquite and oak) with higher gradient. Selection of these areas depended upon the amount of use of the area by the species and its relative proximity to other selected areas. As a result, these habitat sites were selected on a case-by-case basis to provide for the variability of habitat use by the species in these areas.

We have not included critical habitat units within Oregon or Washington because the species has been extirpated as a breeder from those States since at least the 1940s (Littlefield 1988, p. 2; Washington Department of Fish and Wildlife 2013, pp. 200-201), and recent observations of the species, although promising, have not coincided for the most part with suitable breeding habitat and appear to be dispersing but not breeding birds. We also did not include occupied areas within Montana, Nevada, and Wyoming. The reasons for not including critical habitat in these States is that we believe that sufficient areas already have been identified within this revised proposed designation and these areas do not meet our conservation strategy for designating critical habitat. The conservation strategy focuses on areas with confirmed breeding. No confirmed breeding has been identified in Montana or Wyoming. In Nevada, the only known areas where the western yellow-billed cuckoo has confirmed breeding is in the southern part of the State near the borders of California and Arizona. These habitats are essentially the same as those identified in the southwest in Arizona and New Mexico, but do not significantly contribute to population numbers for the western yellow-billed cuckoo. Should we receive information during the public comment period that supports designating as critical habitat areas not included in the revised proposed units (see Revised Proposed Critical Habitat Designation, below), we will reevaluate our current revised proposal.

Sources of data reviewed or cited for this species in the development of critical habitat include peer-reviewed articles, information maintained by universities and State agencies, existing State management plans, species-specific reports, habitat information sources, climate change studies, incidental detections, and numerous survey efforts conducted throughout the species' range, including but not limited to the more recent information below: Corman and Magill 2000; Dockens and Ashbeck 2011; Salt River Project 2011a; Beason 2012; Dettling and Seavy 2012; Gardali

et al.

2012; Johnson

et al.

2012; McCarthy 2012; McNeil

et al.

2012; Sechrist

et al.

2012; Greco 2013; IPCC 2013a; Johnson

et al.

2013c; McNeil

et al.

2013b; Pederson

et al.

2013; Rohwer and Wood 2013; Scribano 2013; Sechrist

et al.

2013; Stromberg

et al.

2013; Wallace

et al.

2013; WestLand Resources 2013a, b, c; American Birding Association 2014,; Ault

et al.

2014; Garfin

et al.

2014; IPCC 2014; Melillo

et al.

2014; Orr

et al.

2014; Stanek 2014; Villarreal

et al.

2014; Dettling

et al.

2015; Griffen 2015; Hughes 2015; MacFarland and Horst 2015, 2017; Van Dooremolen 2015; WestLand Resources 2015 a,b,c,d,e; Arizona Game and Fish Department 2016-2018; Cornell Lab of Ornithology 2016-2018; Corson 2018; RiversEdge West 2007-2018; and Sferra

et al.

2019. For additional information, see References Cited, below.

The amount and distribution of critical habitat that we are proposing will give the western yellow-billed cuckoo the opportunity to potentially: (1) Maintain its existing distribution; (2) move between areas depending on food, resource, and habitat availability; (3) increase the size of the population to a level where it can withstand potentially negative genetic or demographic impacts; and (4) maintain its ability to withstand local- or unit-level environmental fluctuations or catastrophes.

When determining the revised proposed critical habitat boundaries, we made every effort to avoid including developed areas, such as lands covered by buildings, pavement, and other structures, because such lands lack physical or biological features for the western yellow-billed cuckoo. The scale of the maps we prepared under the parameters for publication within the Code of Federal Regulations may not reflect the exclusion of such developed lands. Any such lands inadvertently left inside critical habitat boundaries shown on the maps of this revised proposed rule have been excluded by text in the proposed rule and are not proposed for designation as critical habitat. Therefore, if the critical habitat is finalized as proposed, a Federal action involving these nonhabitat lands would not trigger consultation under section 7 of the Act with respect to critical habitat and the requirement of no adverse modification, unless the specific action would affect the physical or biological features of designated habitat surrounding or adjacent to the nonhabitat areas.

The critical habitat designation is defined by the maps, as modified by any accompanying regulatory text, presented at the end of this document in the Proposed Regulation Promulgation section. We include more detailed

information on the boundaries of the critical habitat designation in the unit descriptions below. We will make the coordinates or plot points or both on which each map is based available to the public on the internet at

http://www.regulations.gov

at Docket No. FWS-R8-ES-2013-0011, and at the Sacramento Fish and Wildlife Office at

http://www.fws.gov/sacramento

(see

FOR FURTHER INFORMATION CONTACT

, above).

Physical or Biological Features

In accordance with section 3(5)(A)(i) of the Act and regulations at 50 CFR 424.12(b), in determining which areas within the geographical area occupied by the species at the time of listing to designate as critical habitat, we consider the physical or biological features that are essential to the conservation of the species and which may require special management considerations or protection. For example, essential physical features for various species might include gravel of a particular size required for spawning, alkali soil for seed germination, protective cover for migration, or susceptibility to flooding or fire that maintains necessary early-successional habitat characteristics. Biological features might include prey species, forage grasses, specific kinds or ages of trees for roosting or nesting, symbiotic fungi, or a particular level of nonnative species consistent with conservation needs of the listed species. The features may also be combinations of habitat characteristics and may encompass the relationship between characteristics or the necessary amount of a characteristic needed to support the life history of the species.

In considering whether features are essential to the conservation of the species, we may consider an appropriate quality, quantity, and spatial and temporal arrangement of habitat characteristics in the context of the life-history needs, condition, and status of the species. These characteristics include, but are not limited to, space for individual and population growth and for normal behavior; food, water, air, light, minerals, or other nutritional or physiological requirements; cover or shelter; sites for breeding, reproduction, or rearing (or development) of offspring; and habitats that are protected from disturbance.

We derive the specific physical or biological features required for the western yellow-billed cuckoo from studies of this species' habitat, ecology, and life history as described below. Additional information can be found in the proposed and final listing rules published in the

Federal Register

on October 3, 2013 (78 FR 61621), and October 3, 2014 (79 FR 59992), respectively. The physical or biological features identified here focus primarily on breeding habitat and secondarily on foraging habitat because most of the habitat relationship research data derive from studies of these activities. Much less is known about migration, stop-over, or dispersal habitat within the breeding range; however, for these purposes, western yellow-billed cuckoos do use a variety of habitats that may or may not be used for breeding. As a result, we do not think that habitat for these purposes is limiting and we have not specifically identified areas for these purposes in our designation. As stated above, the species' use of an area for breeding purposes depends on food availability and habitat conditions. If those conditions are not adequate (

i.e.,

prey not present, environmental conditions not favorable), the species may still use the area for the other purposes identified above. Due to the species' capabilities and behavioral response to resource availability, we conclude that conservation of sufficient habitat for breeding will also provide sufficient habitat for the other activities. Although the wintering and nesting habitat for the western yellow-billed cuckoo that occurs outside of the United States is not considered for critical habitat designation, some information on breeding, migration, and wintering habitat outside the United States is provided. We propose to determine that the following physical or biological features are essential to the conservation of the western yellow-billed cuckoo.

Space for Individual and Population Growth and for Normal Behavior

General breeding (nesting) habitat conditions.

The western yellow-billed cuckoo occurs and breeds during the breeding season (generally from May through September) in a subset of its historical range in the western United States. The western yellow-billed cuckoo uses nesting sites in riparian habitat where conditions are typically cooler and more humid than in the surrounding environment (Gaines and Laymon 1984, p. 75; Laymon 1998, pp. 11-12; Corman and Magill 2000, p. 16). Riparian habitat characteristics, such as dominant tree species, size and shape of habitat patches, tree canopy structure, vegetation height, and vegetation density, are important parameters of western yellow-billed cuckoo breeding habitat. Western yellow-billed cuckoos are found across the DPS in riparian woodlands along low-gradient streams with large patches of cottonwood (

Populus

spp.) and willow (

Salix

spp.) riparian vegetation usually with an overstory and understory component of other tree species, including but not limited to boxelder (

Acer negundo

); ash (

Fraxinus

spp.); walnut (

Juglans

spp.); and sycamore (

Platanus

spp.) (Gaines 1974b, pp. 7-9; Gaines and Laymon 1984, pp. 59-66; Groschupf 1987 pp. 5, 8-11, 16-18; Laymon and Halterman 1989, pp. 274-275; Corman and Magill 2000, pp. 5, 10, 11, 15, 16; Dettling and Howell 2011a, pp. 27-28). In California, the species is typically found in riparian woodland areas along low-gradient streams with large patches of cottonwood (

Populus

spp.) and willow (

Salix

spp.) riparian vegetation with an overstory and understory component of other tree species, including but not limited to boxelder (

Acer negundo

); Oregon ash (

Fraxinus latifolia

); California black walnut (

Juglans californica

); California sycamore (

Platanus racemosa

); Fremont cottonwood (

Populus fremontii

); and valley oak (

Quercus lobata

) (Gaines 1974b, pp. 7-9; Gaines and Laymon 1984, pp. 59-66; Laymon and Halterman 1989, pp. 274-275; Dettling and Howell 2011a, pp. 27-28).

In addition to the riparian trees found across the species' range, the vegetation making up the breeding habitat of the western yellow-billed cuckoo in some areas, especially in the more arid Southwest, includes some other native and nonnative xero-riparian and upland non-riparian trees and large shrubs, such as, but not limited to: Mesquite (

Prosopis

spp.), hackberry (

Celtis reticulata

and

C. ehrenbergiana

), soapberry (

Sapindus saponaria

), oak (

Quercus

spp.), acacia (

Acacia

spp.,

Senegalia greggi

), mimosa (

Mimosa

spp.), greythorn (

Ziziphus obtusifolia

), desert willow (

Chilopsis linearis

), juniper (

Juniperus

spp.), Arizona cypress (

Cupressus arizonica

), pine (

Pinus

spp.), alder (

Alnus rhombifolia

and

A. oblongifolia

), wolfberry (

Lycium

spp.), Russian olive (

Elaeagnus angustifolia

), and tamarisk (

Tamarix

spp.) (Groschupf 1987 pp. 5, 8-11, 16-18; Corman and Magill 2000, pp. 10, 15, 16; Corson 2018, pp. 5, 6-20; Sferra

et al.

2019, p. 3).

Western yellow-billed cuckoo nests have been documented in Fremont cottonwood, Goodding's black willow (

Salix gooddingii

), red willow (

Salix laevigata

), coyote willow (

Salix exigua

), Arizona sycamore, mesquite, tamarisk, hackberry, boxelder, soapberry, Arizona walnut, acacia, ash, alder, seep willow (

Baccharis salicifolia

), English walnut (

Juglans regia

), oak, juniper, and Arizona cypress (Laymon 1980, pp. 6-8; Laymon 1998, p. 7; Hughes 1999, p. 13; Corman and Magill 2000, p. 16; Halterman 2001, p. 11; Halterman 2002,

p. 12; Halterman 2003, p. 11; Halterman 2004, p. 13; Corman and Wise-Gervais 2005, p. 202; Halterman 2005, p. 10; Halterman 2007, p. 5; Holmes

et al.

2008, p. 21; McNeil

et al.

2013, pp. I-1-I-3; Tucson Audubon 2015, p. 44; Groschupf 2015, entire; MacFarland and Horst 2015, pp. 9-12; Sferra

et al.

2019, p. 3).

Western yellow-billed cuckoos have also been found nesting in orchards adjacent to riparian habitat during the breeding season (Laymon 1980, pp. 6-8; Laymon 1998, p. 5). Five pairs of western yellow-billed cuckoos were found nesting along the Sacramento River in a poorly groomed English walnut orchard that provided numerous densely foliaged horizontal branches on which western yellow-billed cuckoos built their nests (Laymon 1980, pp. 6-8). These western yellow-billed cuckoos that nested in the orchard did not forage there, but flew across the river to forage in riparian habitat. Kingsley (1989, p. 142) described western yellow-billed cuckoos as being abundant in the pecan groves in Green Valley and Sahuarita, Arizona, with an estimated density of one nesting pair per 10 ac (4 ha). We consider these agricultural nesting sites to be the exception rather than the preferred nesting habitat for the species due to the paucity of reports identifying such nesting. In mapping the boundaries of the proposed critical habitat, we avoided identifying agricultural lands within the proposed designation. Any agricultural lands inadvertently within the boundary of the proposed designation would not be considered critical habitat because it does not contain the physical or biological features. We request comment on whether any unit of its proposed designation of critical habitat inadvertently includes agricultural lands.

Tamarisk is also a riparian species that may be associated with breeding under limited conditions in the Southwest. Western yellow-billed cuckoos will sometimes build their nests and forage in tamarisk, but there is usually a native vegetation component within the occupied habitat (Gaines and Laymon 1984, p. 72; Johnson

et al.

2008a, pp. 203-204). See “Tamarisk” section below for further discussion of tamarisk as habitat.

Older studies were geographically limited in their scope but nevertheless established a suite of habitat characteristics that became the archetype for western yellow-billed cuckoo breeding habitat. However, habitat conditions across the DPS range vary considerably, and more recent investigations that included other areas within the western yellow-billed cuckoo's breeding range found that large areas of riparian woodland vegetation are not the only areas used by the species for nesting. We describe both the rangewide and southwestern breeding habitat below with particular emphasis on describing the southwestern habitat, because it is less well known as providing habitat for the western yellow-billed cuckoo.

Rangewide breeding habitat.

As stated above, rangewide breeding habitat exists primarily in riparian areas along low-gradient streams, with large patches of cottonwood and willow riparian vegetation with an overstory and understory component. The vegetation is often characterized as riparian woodlands. More specifically, rangewide breeding habitat is characterized as having broad floodplains and open riverine valleys that provide wide floodplain conditions. The general habitat characteristics are areas that are often greater than 325 feet (ft) (100 meter (m)) wide, contain low-gradient rivers and streams (surface slope usually less than 3 percent), are part of floodplains created where rivers and streams enter upstream portions of reservoirs or other water impoundments, or are in areas associated with irrigated upland terraces adjacent to water courses or riparian floodplains. The habitat is usually dominated by willow or cottonwood, but sometimes by other riparian species. The habitat has above-average canopy closure (greater than 70 percent), and a cooler, more humid environment than the surrounding riparian and upland habitats. The plant species most often associated with rangewide breeding habitat are identified above (see General Breeding (nesting) Habitat Conditions), and each may be dominant depending on location. These areas contain the moist conditions that support riparian plant communities made up of overstory and understory components that provide breeding sites, shelter, cover, and food resources for the western yellow-billed cuckoo. However, all foraging needs may not be provided within areas of critical habitat. Western yellow-billed cuckoo use rangewide breeding habitat as described above throughout the DPS, including where it occurs in the Southwest and the states of Sonora and Sinaloa, Mexico.

Southwestern breeding habitat.

In parts of the Southwestern United States and the states of Sonora and Sinaloa, Mexico, western yellow-billed cuckoo breeding habitat is more variable than in the rest of its range. Southwestern breeding habitat includes riparian woodland (including mesquite bosque) and desert scrub and desert grassland drainages with a tree component, and Madrean evergreen woodland (oak-dominated) drainages (particularly in southern Arizona). In areas where water is especially limited, but is nonetheless productive in terms of food and cover for western yellow-billed cuckoos, breeding habitat often consists of narrow, patchy, and/or sparsely vegetated drainages surrounded by arid-adapted vegetation. Due to more arid conditions, southwestern breeding habitat contains a greater proportion of xeroriparian and nonriparian tree species than elsewhere in the DPS. Riparian trees (including xeroriparian) in these ecosystems may even be more sparsely distributed and less prevalent than nonriparian trees.

Southwestern breeding habitat may be less than 325 ft (100 m) wide due to narrow canyons or limited water availability that do not allow for development of wide reaches of habitat. Southwestern breeding habitat is often but not always 200 ac (81 ha) or more in size, and may consist of a series of smaller patches separated by openings. Occurring in both low- and high-gradient drainages, slope does not appear to be a factor in whether or not western yellow-billed cuckoos select these areas for nesting. Often interspersed with large openings, southwestern breeding habitat includes narrow stands of trees, small groves of trees, or sparsely scattered trees. As such, the canopy closure is variable, and where trees are sparsely scattered, it may be dense only at the nest tree. The North American Monsoon brings high humidity and rainfall to some of these habitats especially in the ephemeral drainages in southeastern Arizona where winters are mild and warm wet summers are associated with the monsoon and other tropical weather events (Wallace

et al.

2013a, entire; Erfani and Mitchell 2014, pp. 13,096-13,097).

Riparian drainages in southwestern breeding habitat bisect other habitats and often contain a mix of habitats such as riparian and Madrean evergreen woodland tree species, riparian broadleaf and mesquite-bosque, riparian and desert grassland tree and large shrub species, or riparian and desert scrub tree and large shrub species. More than one vegetation type within and adjacent to the drainage may contribute toward nesting habitat. For example, mesquite, with deeper roots that can reach the water table, often flanks the upland perimeter of more water-dependent cottonwood-willow riparian habitat. Drainage bottoms in these habitats consist of both riparian and

nonriparian trees and may be dominated by cottonwood, willow, xeroriparian tree species (

e.g.,

hackberry, ash, sycamore, walnut), or oak (Sogge

et al.

2008, pp. 148-149; Johnson

et al.

2012, pp. 20-21; WestLand Resources, Inc. 2013a, pp. 3-5; Villarreal

et al.

2014, p. 58; Griffin 2015, pp. 17-25; MacFarland and Horst 2015, pp. iiii, 2, 5-7; Westland Resources, Inc. 2015a, pp. 3-4; Westland Resources, Inc. 2015b, pp. 3-4; Westland Resources, Inc. 2015c, entire).

Common riparian trees (including xeroriparian trees) include cottonwood, willow, mesquite, boxelder, sycamore, ash, alder, walnut, soapberry, desert willow, hackberry, Arizona cypress, tamarisk, and Russian olive. Common nonriparian trees and large shrubs include oak, pinyon, juniper, acacia, greythorn, mimosa, mesquite (upland), and sometimes other pine species (NatureServe 2013, pp. 11-18, 42-113, 132-140). In Arizona, occupied habitat within a single drainage may include both rangewide breeding habitat and southwestern breeding habitat, transitioning from large stands of gallery riparian forest to mesquite woodland, or narrow or patchy stands of more xeroriparian habitat. These drainages include but are not limited to parts of the Gila River, upper Verde River, Blue River, Eagle Creek, Tonto Creek, San Francisco River, Aravaipa Creek, San Pedro River, lower Cienega Creek, and the Rio Grande (Corman and Magill 2000, pp. 37-48; Sogge

et al.

2008, pp. 148-149; Johnson

et al.

2012, pp. 20-21; Cornell Lab of Ornithology 2016 (eBird data); Arizona Game and Fish Department 2018, entire).

In southeastern Arizona, occupied southwestern breeding habitat contains a more arid mix of both southwestern riparian and Madrean evergreen woodland tree species, riparian broadleaf trees and mesquite bosque, riparian and desert grassland tree and large shrub species, or riparian and desert scrub tree and large shrub species. This habitat is found in drainages in the Santa Catalina Mountains, Rincon Mountains, Santa Rita Mountains, Patagonia Mountains, Huachuca Mountains, Pajarito/Atascosa Mountains, Whetstone Mountains, Dragoon Mountains, and Buenos Aires National Wildlife Refuge, among others (Corman and Magill 2000, pp. 37-48; WestLand Resources, Inc. 2013a, pp. 3-5; Westland Resources, Inc. 2013b, pp. 1-9; Griffin 2015, pp. 17-25; MacFarland and Horst 2015, pp. i-iii, 2, 5-7; Tucson Audubon 2015, p. 44; WestLand Resources, Inc. 2015a, pp. 3-4; WestLand Resources, Inc. 2015b, pp. 3-4; WestLand Resources, Inc. 2015d, entire; Cornell Lab of Ornithology 2016 (eBird data), Corson 2018, pp. 5, 20; Rorabaugh 2019,

in litt,

entire; Sferra

et al.

2019, pp. 3-6). In Sonora and Sinaloa, Mexico, western yellow-billed cuckoos also breed in similar riparian habitat bisecting mesquite-dominated woodlands, and semidesert and desert scrub and grassland habitats (Russell and Monson 1998, p. 131). We summarize information on southwestern breeding habitat that is made up of southwestern riparian, desert scrub and grassland drainages with a tree component, and Madrean evergreen woodland drainage habitats below.

Southwestern riparian habitat.

This more arid riparian woodland occurs in perennial and intermittent drainages and floodplains. The extent of riparian vegetation is often narrower, patchier, and sparser than in breeding habitat elsewhere due to limited water for riparian tree regeneration and survival. Trees may occur in narrow linear reaches, in small and patchy groves, or sparsely scattered along the drainage or floodplain. This habitat is often composed of a greater proportion of more arid-adapted riparian tree species and/or is more sparsely vegetated than rangewide riparian breeding habitat. The proportion of cottonwood and willow declines as water becomes more limited. Southwestern riparian breeding habitat may transition into xeroriparian habitat within a single drainage. Narrow or patchy riparian breeding habitat is often found intersecting desert scrub, desert grassland, and Madrean evergreen woodland breeding habitat.

Remnant mesquite bosques, historically extensive throughout the Southwest along major rivers, still occupy some wide floodplains in parts of Arizona and New Mexico. These remnant mesquite bosques include parts of the lower Colorado River, Gila, Salt, San Pedro, Santa Cruz, and Rio Grande Rivers. In Sonora, Mexico, mesquite bosques where western yellow-billed cuckoos have nested have also been greatly reduced (Russell and Monson 1988, p. 131). Southwestern mesquite bosque breeding habitat is often found flanking the outer edge of riparian habitat, where the water table is too deep for cottonwood and willow trees. For example, Arizona's upper San Pedro River contains extensive reaches of mesquite bosque breeding habitat adjacent to the cottonwood and willow dominated breeding habitat in a broad floodplain.

Arid conditions and water management in the Southwest often influences stream flows into and downstream of reservoirs, limiting riparian vegetation regeneration, growth, and survival. In Arizona and New Mexico, narrow or patchy riparian breeding habitat can be found adjacent to heavily managed floodplains (such as areas within Caballo Reservoir and the Lower Rio Grande for example (White

et al.

2018, pp. 26-27)). Hydrologically perennial systems become intermittent or ephemeral due to reservoir management or water delivery requirements. For example, water abundance at Caballo Reservoir and downstream on the Lower Rio Grande varies from year to year and timing of release may not occur prior to or throughout the western yellow-billed cuckoo breeding season. As a result, riparian (including xeroriparian) habitat may persist only as narrow bands or scattered patches along the bankline or as small in-channel islands, or sections of undisturbed native willows within the reservoir. Habitat within these areas may be as small as approximately 30 ac (12 ha) and are typically composed of either willow, tamarisk, or a mix of the two (White

et al.

2018, pp. 26-27). Adjacent habitat may include mowed nonnative vegetation typically less than 1 ft (0.3 m) tall or higher terraces within the floodplain with mesquite or other drought tolerant vegetation.

Desert scrub and desert grassland drainages (with a tree component).

These Southwestern breeding habitats include drainages with a tree component intersecting desert scrub and desert grassland in intermittent and ephemeral drainages. Tree and large shrub species such as mesquite, hackberry, acacia, mimosa, and or greythorn are always present (NatureServe 2013, pp. 88, 134). Riparian (including xeroriparian) trees and large shrubs may have a minor presence in the drainage bottoms. Tree density ranges from sparse to dense in the drainage bottom and adjacent hillside.

Madrean evergreen woodland drainage habitat.

This plant community is dominated by evergreen oak species, but often contains other tree species such as mesquite, juniper, acacia, and hackberry (Brown 1994, pp. 59-62) and is found in southeastern Arizona and southwestern New Mexico's mountain ranges, and resembles habitat found in the Sierra Madre Occidental of Mexico. Western yellow-billed cuckoos breed in the intermittent and ephemeral drainages bisecting Madrean evergreen woodlands in the bajadas, foothills, and mountains of southeastern Arizona (Corman and Magill 2000, pp. 37-48; WestLand Resources, Inc. 2013a, pp. 3-5; Westland Resources 2013b, pp. 1-9; American Birding Association 2014, entire; Cornell Lab of Ornithology 2015

(eBird data); Griffin 2015, pp. 17-25; MacFarland and Horst 2015, pp. i-iii, 2, 5-7; WestLand Resources, Inc. 2015a, pp. 3-4; WestLand Resources, Inc. 2015b, pp. 3-4; Westland Resources, Inc. 2015c, entire; Dillon

et al.

2018, pp. 31-33; White

et al.

2018, pp. 26-27; Sferra

et al.

2019, pp. 3, 9-11). Riparian (including xeroriparian) trees and large shrubs may be present, but are often sparsely distributed or in a narrow band along the drainage bottom. The hillsides immediately adjacent to the tree-lined drainages range from dense woodlands to sparsely treed savannahs with a variety of grasses, contributing toward foraging and breeding habitat for the western yellow-billed cuckoo (Brown 1994, pp. 59-62; Corman and Magill 2000, pp. 37-48; Westland Resources, Inc. 2013a, pp. 3-5; Westland Resources, Inc. 2013c, pp. 1-9; American Birding Association 2014, entire; Cornell Lab of Ornithology 2015 (eBird data); Arizona Game and Fish Department 2015, entire; MacFarland and Horst 2015, pp. 9-12; Westland Resources, Inc. 2015a, pp. 3-4; Westland Resources, Inc. 2015b, pp. 3-4; Westland Resources, Inc. 2015c, entire; Corson 2018, entire).

In 2015, western yellow-billed cuckoos were found in the Coronado National Forest using the Madrean evergreen woodland drainages dominated by oak trees, often with mesquite trees flanking the riparian strip (MacFarland and Horst 2015, pp. 1, 7). The drainages often merge into the surrounding vegetation of juniper. In the wettest reaches of the drainages, the oaks are interspersed with Arizona sycamore, hackberry, willows, occasionally cottonwoods, and a few other infrequently occurring species such as Arizona ash and Arizona walnut (MacFarland and Horst 2015, p. 1). Total canopy cover in occupied habitat was about 52 percent, with oaks as the predominant overstory species recorded (overall average 35 percent), followed by mesquite (20 percent), and juniper (16 percent). The most frequent riparian overstory species were sycamore (3 percent) followed by hackberry (5 percent) and willow (2 percent). The average height of the most prevalent overstory tree species at each point recorded was 20 ft (6.1 m). Habitat occupied during the breeding season (which we also refer to as territories even though western yellow-billed cuckoos may not defend habitat (Hughes 2015, p. 3)) tended to have a higher percentage of mesquites in the community composition, while unoccupied survey points had a higher percentage of junipers (MacFarland and Horst 2015, pp. 9-10). Western yellow-billed cuckoo detections ranged in elevation from 3,564 to 5,480 ft (1,086 to 1,670 m) (MacFarland and Horst 2015, p. 10).

Few western yellow-billed cuckoo detection records in southwestern New Mexico exist between 1998 and 2014 in Madrean evergreen woodland and mesquite woodlands (including other thorn trees and shrubs) habitat similar to southeastern Arizona (Cornell Lab of Ornithology 2016 (eBird)). Much of the southwestern New Mexico habitat is privately owned and is not visited as frequently by birders as is southeastern Arizona. No protocol surveys have been conducted in these areas. Based on the best available survey information, we have not identified confirmed breeding or breeding occupancy in Madrean evergreen woodland and mesquite woodlands in New Mexico. Therefore, no critical habitat is proposed in similar southwestern habitat in southwestern New Mexico because it does not meet our conservation strategy for designating critical habitat.

Tamarisk.

Tamarisk, also known as saltcedar, is a common nonnative shrubby tree found occurring along or within stream courses in western yellow-billed cuckoo riparian habitat in southwestern breeding habitat. Tamarisk, as a component of wildlife habitat, is often characterized as being poor habitat for many species of wildlife, but it can be a valuable substitute where the hydrology has been altered to the extent that native woodland habitat can no longer exist (Service 2002, pp. K-11-K-14; Sogge

et al.

2008, pp. 148-152; Shafroth

et al.

2010b, entire). The spread of tamarisk and the loss of native riparian vegetation is primarily a result of land and water management actions. Tamarisk does not invade and out-compete native vegetation in the Southwest (Service 2002, p. H-11). Rather, human actions have facilitated tamarisk dispersal to new locales, and created opportunities for its establishment by clearing vegetation, modifying physical site conditions, altering natural river processes, and disrupting biotic interactions (Service 2002, p. H-11). Because the presence and relative dominance of tamarisk is greatly influenced by hydrologic regime and depth to groundwater, native riparian vegetation in tamarisk-dominated systems is unlikely to reestablish unless the hydrologic regime is restored (Stromberg

et al.

2007, pp. 381-391).

Johnson

et al.

(2008a, pp. 203-204) conducted Arizona surveys in historically occupied western yellow-billed cuckoo riparian habitat in the late 1990s and found 85 percent of all western yellow-billed cuckoo detections in habitat dominated by cottonwood with a strong willow and mesquite understory, 11.5 percent within mixed native and tamarisk habitats, 3.5 percent within mixed native and Russian olive habitats, and only 5 percent within tamarisk-dominated habitats (Johnson

et al.

2010, pp. 204-205). Even in the tamarisk-dominated habitat, cottonwoods were still present at all but two of these sites.

Although tamarisk monocultures generally lack the structural diversity of native riparian habitat, western yellow-billed cuckoos may use these areas for foraging, dispersal, and breeding, especially if the tamarisk-dominated sites retain some native trees. Tamarisk contributes cover, nesting substrate, temperature amelioration, increased humidity, and insect production where native habitat regeneration and survivability has been compromised by altered hydrology (

e.g.,

reduced flow or groundwater availability) and hydrologic processes (

e.g.,

flooding and sediment deposition). In parts of the western yellow-billed cuckoo's range, some tamarisk-dominated sites are used for nesting and foraging including parts of the Bill Williams, Verde, Gila, Salt, and Rio Grande Rivers (Groschupf 1987, pp. 9, 15; Corman and Magill 2000, pp. 11, 14-16, Leenhouts

et al.

2006, p. 15; Sogge

et al.

2008, p. 148; Sechrist

et al.

2009, p. 55; Dockens and Ashbeck 2011a, pp. 1, B-26; Dockens and Ashbeck 2011b, pp. 8, D-2; Jarnevich

et al.

2011, p. 170; McNeil

et al.

2013b, p. I-1; Arizona Game and Fish Department 2014, pp. 1-5; Jakle 2014, entire; Orr

et al.

2014, p. 25; Salt River Project 2014, entire; Service 2014, p. 63; Arizona-Sonora Desert Museum 2016, entire; Dillon

et al.

2018 pp. 31-33; White

et al.

2018 pp. 26-27; and Parametrix, Incorporated (Inc.) and Southern Sierra Research Station 2019, p. 5-1).

Past restoration efforts favored nonnative tamarisk removal without regard for its habitat suitability for the western yellow-billed cuckoo. In areas where tamarisk is a major component (or part of the understory), its removal may not be appropriate or recommended because western yellow-billed cuckoo habitat selection may be based on overstory/understory structure and not on specific vegetation types (Sechrist

et al.

2009, p. 53). In some areas, if tamarisk is removed, the remaining habitat may be rendered unsuitable because it is more exposed, hotter, and drier.

Another issue in regards to tamarisk is the introduction of biocontrol agents

to remove tamarisk. In 2001, the U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) released various species of the nonnative tamarisk leaf beetle (

Diorhabda

sp.) in an effort to control tamarisk invasion (APHIS 2005, p. 4-5). Since 2001, the tamarisk leaf beetle has expanded rapidly and its distribution now encompasses much of the western United States (RiversEdge West, 2018, entire). This expansion of tamarisk defoliation will lead to habitat degradation and may render areas unsuitable for occupancy by the western yellow-billed cuckoo (Sogge

et al.

2008, p. 150). Defoliation during the breeding season also exposes eggs and nestlings to heat exposure and predation from decreased cover, as was documented in 2008 in St. George, Utah, with the exposure-caused failure of an active southwestern willow flycatcher nest (Paxton

et al.

2011, p. 257). In defoliated areas of the Rio Grande, canopy cover was still within the natural range of variation; however, the canopy cover was composed of dead leaves as opposed to live leaves, which changed the microclimate (Dillon and Ahlers 2018, pp. 26-27). Ultimately, the sampled areas with the most tamarisk and subsequent defoliation activity reflected the areas with the highest temperature extremes (Dillon and Ahlers 2018, pp. 26-27).

Some tamarisk removal and native tree replacement projects are under way to offset the arrival of tamarisk leaf beetles and subsequent defoliation (Service 2016b, pp. 4-15). If these projects are unsuccessful in sustaining native woodland habitat of at least the same habitat value as habitat that was removed, the end result will be a net loss of habitat. Another nonnative species identified as a biocontrol agent, the tamarisk weevil (

Coniatus

sp.) has also been found in the wild in Arizona, California, Nevada, and Utah (Eckberg and Foster 2011, p. 51; Eichhorst

et al.

2017, entire). The impact of the tamarisk weevil has not been well studied and currently has not been shown to significantly impact tamarisk-dominated habitats used by the western yellow-billed cuckoo.

Breeding (nesting) habitat and home range size.

In rangewide western yellow-billed cuckoo habitat, the habitat used for breeding and nesting by the species varies in size and shape. The available information indicates that the species requires large tracts of habitat for breeding and foraging during the nesting season (home range). The larger the extent of habitat, the more likely it will provide suitable habitat for the western yellow-billed cuckoos and be occupied by nesting pairs (Laymon and Halterman 1989, pp. 274-275). Rangewide breeding habitat can be relatively dense contiguous stands or irregularly shaped mosaics of dense vegetation with more sparse or open areas.

Along the Colorado River in California and Arizona, western yellow-billed cuckoos tend to favor larger riparian habitat sites for nesting (Laymon and Halterman 1989, p. 275): sites less than 37 ac (15 ha) are considered unsuitable nesting habitat; sites between 37 ac (15 ha) and 50 ac (20 ha) in size were rarely used as nest sites; and habitat patches or aggregates of patches from 50 to 100 ac (20 to 40 ha) in size were considered marginal habitat (Laymon and Halterman 1989, p. 275). Habitat areas between 100 ac (40 ha) and 200 ac (81 ha), although considered suitable, are not consistently used by the species in California. The optimal size of habitat patches (aggregates of trees that may be interspersed with openings, sparse understory or canopy, or open floodplains) for the western yellow-billed cuckoo are generally greater than 200 ac (81 ha) in extent and have dense canopy closure and high foliage volume of willows and cottonwoods in at least a portion of the overall habitat patch (Laymon and Halterman 1989, pp. 274-275) and thus provide adequate space for nesting and foraging.

In rangewide riparian breeding habitat and mixed riparian habitat in California, Arizona, and New Mexico, the home ranges used by the western yellow-billed cuckoo during the breeding season varied greatly but averaged over 100 ac (40 ha) (Laymon and Halterman 1987, pp. 31-32; Halterman 2009, p. 93; Sechrist

et al.

2009, p. 55; McNeil

et al.

2010, p. 75; McNeil

et al.

2011, p. 37; McNeil

et al.

2012, p. 69; McNeil

et al.

2013a, pp. 133-134; McNeil

et al.

2013b, pp. 49-52). On the Rio Grande in New Mexico, Sechrist

et al.

(2009, p. 55) estimated a large variation in home range size, ranging from 12 to 697 ac (5 to 282 ha), and averaging 202 ac (82 ha). On the upper San Pedro River in Arizona, Halterman (2009, pp. 67, 93) also estimated a large variation in home range size, ranging from 2.5 to 556 ac (1 to 225 ha), and averaging 126 ac (51 ha). In the intermountain west (Idaho, Utah, Colorado), the western yellow-billed cuckoo breeds in similar habitats as described above but are more scattered and in lower density (Parrish

et al.

1999, p. 197; Taylor 2000, pp. 252-253; Idaho Fish and Game 2005, entire; Wiggins 2005, p. 15). These measures suggest that the amount of habitat required to support nesting western yellow-billed cuckoos even in rangewide riparian breeding habitat is variable.

Home range size is unknown in southwestern breeding habitat, including in more xeroriparian woodland, desert scrub and desert grassland drainages with a tree component and in Madrean evergreen woodland. Whether the area is considered marginal, suitable, or optimal depends on numerous factors and is variable across the species' range. Breeding habitat in more arid regions of the Southwest may be made up of a series of adjacent or nearly adjacent habitat patches, less than 200 ac (81 ha) each, which combined make up suitable breeding habitat for the species. Often interspersed with large openings, these habitat patches include narrow stands of trees, small groves of trees, or sparsely scattered trees. For example, in the Agua Fria River in central Arizona, occupied habitat consists not only of mature cottonwood and willow gallery forest (multi-aged and multi-height forest) found in rangewide breeding habitat, but also smaller patches of young willows that are limited to narrow riparian corridors with mesquite on the adjacent terrace characteristic of southwestern breeding habitat (Prager and Wise 2015, p. 13). In the bajadas, foothills, and mountain drainages of southeastern Arizona, scattered overstory trees, small patches of trees, or narrow stands of trees contain suitable breeding habitat (MacFarland and Horst 2015, entire, Corson 2018, pp. 5, 6-20; Sferra

et al.

2019, entire).

Although large expanses of habitat are better than small patches for the species, small habitat patches should be evaluated when managing for the western yellow-billed cuckoo. The optimal minimum breeding habitat patch size of 200 ac (81 ha) may not be applicable for much of the Southwest, where breeding habitat may be narrower and patchier and areas of less than 40 ac (16 ha) may be used for breeding (Sechrist

et al.

2009, p. 55; White

et al.

2018, pp. 14-37). These smaller sites support fewer western yellow-billed cuckoos, but collectively they may be important for achieving recovery.

Western yellow-billed cuckoos appear to stage in southern Arizona or northern Mexico pre- and post-breeding, suggesting that this region is important to the DPS (McNeil

et al.

2015, pp. 249, 251). Some individuals also roam widely (several hundred miles), apparently assessing food resources prior to selecting a nest site (Sechrist

et al.

2012, pp. 2-11). A plausible explanation for prolonged presence in southern Arizona and northwestern Mexico pre- and post-breeding may be

that western yellow-billed cuckoos are taking advantage of increased insect production in the monsoonal area. Identifying and maintaining habitat across the species' range is important to allow the species to take advantage of variable environmental conditions for successful breeding opportunities.

Foraging area.

Western yellow-billed cuckoos select a nesting site based on optimizing the near-term foraging potential of the neighborhood (Wallace

et al.

2013a, p. 2102). Given that western yellow-billed cuckoos are larger birds with a short hatch-to-fledge time, the adults must have access to abundant food sources to successfully rear their offspring. Optimal foraging habitat contains a mixture of overstory and understory vegetation (typically cottonwoods and willows) that provides for diversity and abundance of prey. Western yellow-billed cuckoos generally forage within the tree canopy, and the higher the foliage volume the more likely western yellow-billed cuckoos are to use a site for foraging (Laymon and Halterman 1985, pp. 10-12). Foraging areas can be less dense with lower levels of canopy cover and often have a high proportion of cottonwoods in the canopy. Foraging areas can also include riparian habitat with a high abundance of tamarisk.

The foraging distance and size of foraging habitat required by western yellow-billed cuckoo varies on prey availability and other environmental conditions and may vary annually and from site to site. A foraging area during the breeding season may overlap with other western yellow-billed cuckoo foraging areas if multiple nest sites are within a single area. Hughes (2015, p. 3) suggests that adjacent nesting western yellow-billed cuckoos use time spacing (

i.e.,

no overlap in egg dates) to partition resources, allowing many nesting pairs to share localized short-term abundance of food. In a study in rangewide breeding habitat in the Sacramento Valley, California, the mean size of foraging areas for 4 pairs of western yellow-billed cuckoos was approximately 48 ac (19 ha) (range 27 to 70 ac (11 to 28 ha)) of which about 25 ac (10 ha) was considered usable habitat for foraging (Laymon 1980, p. 20; Hughes 1999, p. 7).

In the southwestern United States and northern Mexico, western yellow-billed cuckoo foraging habitat is usually more arid than adjacent occupied nesting habitat. Western yellow-billed cuckoos not only forage within woodland breeding habitat, but they also forage in almost any adjacent habitat. Desert vegetation in intermittent and ephemeral drainages or adjacent upland areas may require direct precipitation to flourish (Wallace

et al.

2013a, p. 2,102). Other desert areas with spring-fed habitat may provide similar habitat conditions. Both are important features of western yellow-billed cuckoo foraging habitat in the arid Southwest. In Arizona and New Mexico, adjacent foraging habitat includes several types of semidesert scrub, desert scrub, chaparral, semidesert grassland, and desert grassland (Brown and Lowe 1982, entire; Brown 1994, entire; Brown

et al.

2007, pp. 4-5). An exception to the habitat characteristics identified above occurs in New Mexico along the Rio Grande, where 29 percent of all estimated territories in the period 2009-2014 were located in understory vegetation (considered less than 6 m (15 ft) in height) that lacked a canopy component (considered less than 25 percent cover), but included a New Mexico olive (

Forestiera neomexicana

) component (Hamilton 2014, p. 3-84). Of these understory areas, roughly half were dominated by exotic species (primarily tamarisk) (Carstensen

et al.

2015, pp. 57-61). Western yellow-billed cuckoos in New Mexico have also been observed foraging in adjacent habitat up to 0.5 mi (0.8 km) away from nest sites (Sechrist

et al.

2009, p. 49). In the intermountain west (Idaho, Utah, Colorado), the western yellow-billed cuckoo breeds in similar habitats as described above but are more scattered and in lower density (Parrish

et al.

1999, p. 197; Taylor 2000, pp. 252-253; Idaho Fish and Game 2005, entire; Wiggins 2005, p. 15).

Movement corridors and connectivity of habitat.

The western yellow-billed cuckoo is a neotropical migratory species that travels between North, Central, and South America each spring and fall (Sechrist

et al.

2012, p. 5; McNeil

et al.

2015, p. 244; Parametrix, Inc. and Southern Sierra Research Station 2019, pp. 97-108). As such, it needs movement corridors of linking habitats and stop-over sites along migration routes and between breeding areas (Faaborg

et al.

2010, pp. 398-414; Allen and Singh 2016, p. 9). During movements between nesting attempts, western yellow-billed cuckoos have been found at riparian sites with small groves or strips of trees, sometimes less than 10 ac (4 ha) in extent (Laymon and Halterman 1989, p. 274). The habitat features at stop-over and foraging sites are typically similar to the features at breeding sites, but may be smaller in size, may be narrower in width, and may lack understory vegetation. Western yellow-billed cuckoos may be using nonbreeding areas as staging areas or taking advantage of local foraging resources (Sechrist

et al.

2012, pp. 7-9; McNeil

et al.

2015, pp. 250-252). As a result, western yellow-billed cuckoos use nonbreeding or intermittently used breeding areas as staging areas, movement corridors, connectivity between habitats, or foraging sites (taking advantage of local foraging resources). However, because these nonbreeding habitat areas are not limiting, we have not specifically identified them as critical habitat.

Therefore, based on the information above, for the majority of habitat within the species' range, we identify rivers and streams of lower gradient and more open valleys with a broad floodplain, containing riparian woodland habitat with an overstory and understory vegetation component made up of various plant species (most often dominated by willow or cottonwood) to be physical or biological features essential to the conservation of the western yellow-billed cuckoo. In more arid regions of the southwestern United States, we also identify reaches of more xeroriparian habitat (including mesquite bosques), desert scrub, and desert grassland drainages with a tree component, and Madrean evergreen woodland drainages in low- to high-gradient drainages to be a physical or biological feature essential to the conservation of this species. These habitat types provide space for breeding, nesting, and foraging for the western yellow-billed cuckoo. These habitat features also provide for migratory or stopover habitat and movement corridors for the western yellow-billed cuckoo. Food, Water, Air, Light, Minerals, or Other Nutritional or Physiological Requirements

Food.

Western yellow-billed cuckoos eat large insects but also prey on small vertebrates such as frogs (

e.g., Hyla

spp.;

Pseudacris

spp.;

Rana

spp.) and lizards (

e.g., Lacertilia

sp.) (Hughes 1999, p. 8). The diet of the western yellow-billed cuckoo on the South Fork Kern River in California showed the majority of the prey to be the big poplar sphinx moth larvae (

Pachysphinx occidentalis

) (45 percent), tree frogs (24 percent), katydids (22 percent), and grasshoppers (Order

Othoptera

) (9 percent) (Laymon and Halterman 1985, pp. 10-12; Laymon

et al.

1997, p. 7). Minor prey at that site and other sites includes beetles (Order

Coleoptera

sp.), dragonflies (Order

Odonata

), praying mantis (Order

Mantidae

), flies (Order

Diptera

), spiders (Order

Araneae

), butterflies (Order

Lepidoptera

), caddis flies (Order

Trichoptera

), crickets (Family

Gryllidae

), and cicadas (Family Cicadidae) (Laymon

et al.

1997, p. 7;

Hughes 1999, pp. 7-8). In Arizona, cicadas are an important food source (Halterman 2009, p. 112). Western yellow-billed cuckoos on the Buenos Aires National Wildlife Refuge in Arizona were observed eating tent caterpillars, caterpillars of unidentified species, katydids, and lizards (Griffin 2015, pp. 19-20). At upper Empire Gulch in southeastern Arizona, a western yellow-billed cuckoo was photographed in a tree in gallery riparian forest with a leopard frog (

Rana

spp.) in its bill on July 21, 2014 (Barclay 2014, entire; Leake 2014a, b, entire). In the intermountain west (Idaho, Utah, Colorado), the western yellow-billed cuckoo feeds on similar insect species (Parrish

et al.

1999, p. 197; Idaho Fish and Game 2005, p. 2; Wiggins 2005, p. 18).

Western yellow-billed cuckoos depend on an abundance of large, nutritious insect and vertebrate prey to survive and raise young. In portions of the southwestern United States, high densities of prey species may be seasonally found, often for brief periods of time, during the vegetation growing season. The arrival and nesting of western yellow-billed cuckoos typically coincides with the availability of prey, which is later than in the eastern United States (eBird data). Desiccated riparian sites produce fewer suitable insects than moist sites. In areas that typically receive rains during the summer monsoon, an increase in humidity, soil moisture, and surface water flow are important triggers for insect reproduction and western yellow-billed cuckoo nesting (Wallace

et al.

2013a, p. 2,102). Western yellow-billed cuckoos select a nesting site based on optimizing the near-term foraging potential of the habitat (Wallace

et al.

2013a, p. 2,102). Given that western yellow-billed cuckoos are large birds with a short hatch-to-fledge time, the adults must have access to abundant food sources to successfully rear their offspring (Laymon 1980, p. 27). The variability of monsoon precipitation across a region may result in areas with favorable conditions for western yellow-billed cuckoo nesting in one year and less favorable in a different year. In years of high insect abundance, western yellow-billed cuckoos lay larger clutches (three to five eggs rather than two), a larger percentage of eggs produce fledged young, and they breed multiple times (two to three nesting attempts rather than one) (Laymon

et al.

1997, pp. 5-7).

Therefore, we identify the presence of abundant, large insect fauna (

e.g.,

cicadas, caterpillars, katydids, grasshoppers, crickets, large beetles, dragonflies, and moth larvae) and small vertebrates (frogs and lizards) during nesting season of the western yellow-billed cuckoo to be a physical or biological feature essential to the conservation of the species.

Water and humidity.

Rangewide breeding habitat for western yellow-billed cuckoo is largely associated with perennial rivers and streams that support the expanse of vegetation characteristics needed by breeding western yellow-billed cuckoos. Throughout the western yellow-billed cuckoo's range, winter precipitation (as rain or snow) provides water flow to the larger streams and rivers in the late spring and summer. In southwestern breeding habitat, western yellow-billed cuckoos also breed in ephemeral and intermittent drainages, some of which are associated with monsoonal precipitation events. Hydrologic conditions at western yellow-billed cuckoo breeding sites can vary between years. At some locations during low rainfall years, water flow may be reduced or absent, or soils may not become saturated at appropriate times. During high rainfall years, streamflow may be extensive and the riparian vegetation can be inundated and soil saturated for extended periods of time.

The North American Monsoon (monsoon) is a large-scale weather pattern that causes high humidity and a series of thunderstorms during the summer in northwestern Mexico and the southwestern United States (Erfani and Mitchell 2014, pp. 13,096-13,097; National Weather Service 2019, p. 4). It supplies about 60-80 percent of the annual precipitation for northwestern Mexico, 45 percent for New Mexico, and 35 percent for Arizona (Erfani and Mitchell 2014, p. 13,096). The monsoon typically arrives in early to mid-July in Arizona and New Mexico, where much of the rainfall occurs in the mountains (Erfani and Mitchell 2014, pp. 13,096-13,097; National Weather Service 2019, p. 2). The southwestern United States, at the northern edge of the monsoon's range, receives less and more variable rainfall than northwestern Mexico (National Weather Service 2019, p. 2).

Humid conditions created by the North American Monsoon (Erfani and Mitchell 2014, pp. 13,096-13,097; National Weather Service 2019, p. 2) and related surface and subsurface moisture appear to be important for the western yellow-billed cuckoo. The species is restricted to nesting in moist riparian habitat or in drainages that bisect semi-desert, desert grasslands, semi-desert, desert scrub, and Madrean evergreen woodland in the portions of the western United States and northern Mexico because of humidity requirements for successful hatching and rearing of young (Hamilton and Hamilton 1965, p. 427; Gaines and Laymon 1984, pp. 75-76; Rosenberg

et al.

1991, pp. 203-204; Corman and Magill 2000, pp. 37-48; Westland Resources, Inc. 2013a, pp. 3-5; Westland Resources, Inc. 2013c, pp. 1-9; American Birding Association 2014, entire; Arizona Game and Fish Department 2018, entire; Cornell Lab of Ornithology 2018, (eBird data); Westland Resources, Inc. 2015a, pp. 3-4; Service 2018, entire).

Western yellow-billed cuckoos have evolved larger eggs and thicker eggshells, which help them cope with potential higher egg water loss in the hotter, drier conditions of the Southwest (Hamilton and Hamilton 1965, pp. 426-430; Ar

et al.

1974, pp. 153-158; Rahn and Ar 1974, pp. 147-152). Nest sites have lower temperatures and higher humidity compared to areas along the riparian forest edge or outside the forest (Launer

et al.

1990, pp. 6-7, 23). Recent research on the lower Colorado River has confirmed that western yellow-billed cuckoo nest sites had significantly higher daytime relative humidity (6-13 percent higher) and significantly lower daytime temperatures (2-4 degrees Fahrenheit (1-2 degrees Celsius) lower) than average forested sites (McNeil

et al.

2011, pp. 92-101; McNeil

et al.

2012, pp. 75-83).

Seasonal precipitation results in vegetative regeneration in the intermittent and ephemeral drainages and adjacent desert scrub, desert grassland, and Madrean evergreen woodlands of the southwestern United States. High summer monsoonal humidity and rain lead to summer flow events in drainages and increased vegetative growth and associated insect production during the breeding season. The North American Monsoon promotes growth of shallow-rooted understory vegetation in mesquite-dominated woodlands, Madrean evergreen woodlands, desert scrub drainages, desert grassland drainages, and adjacent desert and grassland vegetation (Brown 1994, pp. 59-62; Wallace

et al.

2013a, p. 2,102). The hydrologic processes in Madrean evergreen woodlands, semi-desert and desert scrub drainages, and semi-desert and desert grassland drainages of southeastern Arizona are different than the rest of the range of the western yellow-billed cuckoo. These upland habitats on gently rolling hillsides are interspersed with intermittent or ephemeral drainages. Humidity brought on by the summer monsoon may be an especially important trigger for breeding western

yellow-billed cuckoos in this otherwise dry landscape.

Nesting continues through August and frequently into September in southeastern Arizona, likely in response to the increased food resources associated with the seasonal summer rains (Corman and Wise-Gervais 2005, p. 202). For example, the big poplar sphinx moth is an earth pupator (larvae burrow in the ground, and pupae emerge under certain environmental conditions) (Oehlke 2017, p. 5). The sphinx moth has a receptor that detects the water content of air to sense changes in humidity and when conditions are favorable for feeding and breeding (McFarland 1973, pp. 199-208; von Arx

et al.

2012, p. 9,471). In riparian woodland habitat soil, moisture and humidity cue the sphinx moths to emerge. In Arizona, summer monsoonal precipitation mimics typical riparian woodland soil moisture conditions, which cue the sphinx moth to emerge from the soil. Although sphinx moths are just one of the foods eaten by western yellow-billed cuckoos, we use these moths to illustrate that the unique monsoonal conditions in southeastern Arizona contributing toward food production are an important factor in western yellow-billed cuckoo presence in southeastern Arizona.

A large proportion of the remaining occupied habitat persists in hydrologically altered systems in the Southwest where the timing, magnitude, and frequency of natural flow have changed (Service 2002, pp. J1-J34). Hydrologically altered systems, with less dynamic riverine process than unaltered systems, can support suitable western yellow-billed cuckoo habitat if suitable woodland vegetation as described above is present. As discussed above and in the October 3, 2014,

Federal Register

listing the western yellow-billed cuckoo (79 FR 59992), human actions have cleared vegetation, modified physical site conditions, altered natural river processes, and disrupted biotic interactions along much of the western yellow-billed cuckoo habitat in the west (Service 2002, p. H-11). In the intermountain west (Idaho, Utah, Colorado), similar losses and degradation of habitat have occurred (Parrish

et al.

1999, pp. 200-201; Idaho Fish and Game 2005, p. 3; Wiggins 2005, pp. 22-27). Habitat conditions are greatly influenced by hydrologic regime and depth to groundwater, and native riparian vegetation in altered systems is unlikely to reestablish unless the hydrologic regime is restored (Stromberg

et al.

2007, pp. 381-391). However, these altered systems, which often cannot support the native plant species and structural diversity of unaltered systems, can support more adapted nonnative tree species like tamarisk or Russian olive. Western yellow-billed cuckoos occupy nonnative habitat interspersed with native habitat on the Colorado, Bill Williams, Verde, Gila, Santa Cruz, San Pedro, and Rio Grande Rivers (Corman and Magill 2000, pp. 15-16, 37-48; Sonoran Institute 2008, pp. 30-34; Dockens and Ashbeck 2011a, p. 6; Dockens and Ashbeck 2011b, p. 10; McNeil

et al.

2013b, p. I-1; Arizona Game and Fish Department 2016, entire; Parametrix, Inc. and Southern Sierra Research Station 2019, p. 5-1).

Subsurface hydrologic conditions are equally important to surface water conditions in determining riparian vegetation patterns. Depth to groundwater plays an important part in the distribution of riparian vegetation and western yellow-billed cuckoo habitat. Riparian forest trees need access to shallow groundwater to grow to the appropriate size and density to provide habitat for nesting, foraging, and migrating western yellow-billed cuckoos. Goodding's willows and Fremont cottonwoods do not regenerate successfully if the groundwater levels fall below 6 ft (2 m) from the surface (Shafroth

et al.

2000, pp. 66-75). Goodding's willows cannot survive if groundwater levels drop below 10 ft (3 m), and Fremont cottonwoods cannot survive if groundwater drops below 16 ft (5 m) (Stromberg and Tiller 1996, p. 123). Abundant and healthy riparian vegetation decreases and habitat becomes stressed and less productive when groundwater levels are lowered (Stromberg and Tiller 1996, pp. 123-127).

Therefore, based on the information above, we identify seasonally or perennially flowing rivers, streams, and drainages; elevated subsurface groundwater tables; vegetative cover that provides important microhabitat conditions for successful breeding and prey (high humidity and cooler temperatures); seasonal precipitation (winter and summer) in the Southwest; and high summer humidity as physical and biological features essential to the conservation of the western yellow-billed cuckoo.

Conditions for germination and regeneration of vegetation.

The abundance and distribution of fine sediment deposited on floodplains during flood events is critical for the development, abundance, distribution, maintenance, and germination of riparian tree species. This sediment deposition must be accompanied by sufficient surface moisture for seed germination and sufficient groundwater levels for survival of seedlings and saplings (Stromberg 2001, pp. 27-28). The lack of stream flow processes, which deposit such sediments and clear out woody debris, may lead riparian forested areas to senesce (age and become less productive) and to become degraded and not able to support the varied vegetative structure required for western yellow-billed cuckoo nesting and foraging.

In unmanaged hydrologic systems (natural riverine systems), associated with rangewide breeding habitat, this variability of water flow results in removal of stream banks and deposition of soil and sediments. These sediments provide areas for vegetation (especially cottonwood and willow) to colonize and provide diverse habitat for the western yellow-billed cuckoo. In managed hydrologic systems (systems controlled by dams), stream flow is often muted and does not provide the magnitude of these removal and deposition events except during flood events depending on stream-bank composition (Fremier

et al.

2014, pp. 4-6). However, if these systems are specifically managed to mimic more natural conditions, some removal and deposition can occur. The range and variation of stream flow frequency, magnitude, duration, and timing that will establish and maintain western yellow-billed cuckoo habitat can occur in both managed and unmanaged flow conditions depending on the interaction of the water feature and its floodplain or the physical characteristics of the landscape.

However, successional vegetation change that produces suitable habitat consisting of varied vegetative structure can also occur in managed river and reservoir systems (and in human-altered river systems) when managed to mimic natural stream flows, but sometimes with different vegetation species composition, at different timing, frequency, and magnitude than natural riverine systems. For example, varying amounts of western yellow-billed cuckoo habitat are available from month-to-month and year-to-year as a result of dam operations. During dry years, when lake levels may be low, vegetation can be established and mature into habitat for the western yellow-billed cuckoo. In wet years, this vegetation can be flooded for extended periods of time and be stressed or killed. This is particularly true of areas upstream of reservoirs like Lake Isabella in California, Roosevelt and Horseshoe Reservoirs in Arizona, and Elephant Butte Reservoir in New Mexico, all of which have relatively large western yellow-billed cuckoo populations. The

filling and draw-down of reservoirs often mimics the flooding and drying events associated with intact riparian woodland habitat and river systems providing habitat for the western yellow-billed cuckoo.

In southern Arizona and New Mexico, where water is less available and releases do not mimic the natural hydrograph, riparian habitat is often narrower, patchier, sparser, and composed of more xeroriparian and nonriparian trees and large shrubs than in a free flowing river. Habitat regeneration opportunities occur less frequently than in natural systems or managed systems that mimic the natural hydrograph. Prolonged drying and flooding from reservoir management can also affect food resources and habitat suitability for western yellow-billed cuckoos. For example, food availability is affected when prolonged inundation reduces survivability of ground-dwelling insects such as sphinx moth pupa or katydid eggs (Peterson

et al.

2008, pp. 7-9). Likewise, prolonged drying reduces the vegetation available for prey insects to consume, so less insect biomass is available for western yellow-billed cuckoos.

In the southwestern United States, the North American Monsoon season, which peaks in July and August when western yellow-billed cuckoos are breeding, provides about 45 percent and 35 percent of the annual precipitation for New Mexico and Arizona, respectively (Erfani and Mitchell 2014, p. 13,096). The increased humidity and rains promote rapid and dense herbaceous growth (forbs, grasses, and vines) in occupied habitat in riparian (including xeroriparian) drainages intersecting desert scrub and desert grassland, and Madrean evergreen woodlands. In southeastern Arizona, Madrean evergreen woodland habitat receives half of the annual precipitation during the growing season from May through August (Brown 1994, pp. 60, 62).

Therefore, based on the information above, we identify flowing perennial rivers and streams and deposited fine sediments as physical and biological features essential to the conservation of the western yellow-billed cuckoo. These conditions may occur in either natural or regulated human-altered riverine systems. We also identify intermittent and ephemeral drainages and immediately adjacent upland habitat (which receive moisture as a result of summer monsoon events and other seasonal precipitation) that promote seed germination and regeneration as essential physical or biological features of western yellow-billed cuckoo habitat.

Cover or shelter.

Riparian woodland (including mesquite bosques), desert scrub, and desert grassland drainages with a tree component, and Madrean evergreen woodland vegetation provides the western yellow-billed cuckoo with cover and shelter while foraging and nesting. Placing nests in dense vegetation provides cover from predators that would search for adult western yellow-billed cuckoos, their eggs, nestlings, and fledged young. For example, northern harriers (

Circus cyaneus

) prey on western yellow-billed cuckoo nestlings in open riparian vegetation at restoration sites. Dense vegetation in the habitat patch makes it difficult for northern harriers to prey on species like the western yellow-billed cuckoo (Laymon 1998, pp. 12-14). As noted above, shelter provided by the vegetation also contributes toward providing nesting sites, temperature amelioration, and increased humidity, all of which assist in benefiting the life history of western yellow-billed cuckoo.

Therefore, we identify riparian trees, including but not limited to willow, cottonwood, alder, walnut, sycamore, boxelder, ash, mesquite, and tamarisk, that provide cover and shelter for nesting, foraging, and dispersing western yellow-billed cuckoos as physical or biological features essential to the conservation of the western yellow-billed cuckoo. In more arid riparian woodland, desert scrub, and desert grassland drainages with a tree component, and Madrean evergreen woodland drainages of southeastern Arizona, in addition to the riparian species above we identify oak, upland mesquite, hackberry, sycamore, acacia, juniper, greythorn, mimosa, soapberry, Arizona cypress, desert willow, and pine that provide cover and shelter for nesting, foraging, and dispersing western yellow-billed cuckoos as physical or biological features essential to the conservation of the western yellow-billed cuckoo.

Sites for breeding, reproduction, or rearing (or development) of offspring.

Nest site characteristics in rangewide riparian woodland breeding habitat have been compiled from 217 western yellow-billed cuckoo nests on the Sacramento and South Fork Kern Rivers in California, and the Bill Williams and San Pedro Rivers in Arizona. Western yellow-billed cuckoos generally nest in thickets dominated by willow trees along floodplains greater than 200 ac (81 ha) in extent and greater than 325 ft (100 m) in width. Nests are placed on well-foliaged branches closer to the tip of the branch than the trunk of the tree (Hughes 1999, p. 13). Nests are built from 4 ft to 73 ft (1 m to 22 m) above the ground (average 22 ft (7 m)). Nests at the San Pedro River averaged higher (29 ft (9 m)) than either the Bill Williams River (21 ft (6 m)) or the South Fork Kern River (16 ft (5 m)). Nest trees ranged from 10 ft (3 m) to 98 ft (30 m) in height and averaged 35 ft (11 m). In older stands, heavily foliaged branches that are suitable for nesting often grow out into small forest openings or over sloughs or streams, making for ideal nest sites. In younger stands, nests are more often placed in vertical forks or tree crotches. Nest sites in rangewide riparian breeding habitat are placed in willows (72 percent of 217 nests), in generally willow-dominated sites. Nests have also been documented in other riparian tree species, including Fremont cottonwood (13 percent), mesquite (7 percent), tamarisk (4 percent), netleaf hackberry (

Celtis laevigata

var.

reticulata

) (2 percent), English walnut (

Juglans regia

) (1 percent), boxelder (less than 1 percent), and soapberry (

Sapindus saponaria

) (less than 1 percent) (Laymon 1980, p. 8; Laymon 1998, p. 7; Hughes 1999, p. 13; Corman and Magill 2000, p. 16; Halterman 2001, p. 11; Halterman 2002, p. 12; Halterman 2003, p. 11; Halterman 2004, p. 13; Corman and Wise-Gervais 2005, p. 202; Halterman 2005, p. 10; Halterman 2007, p. 5; Holmes

et al.

2008, p. 21).

Canopy cover directly above the nest is generally dense (averages cover is 89 percent) and is denser at the South Fork Kern River (93 percent) and Bill Williams River (94 percent) than at the San Pedro River (82 percent). Canopy closure in a plot around the nest averages 71 percent and was higher at the Bill Williams River (80 percent) than at the South Fork Kern River (74 percent) or San Pedro River (64 percent) (Laymon

et al.

1997, pp. 22-23; Halterman 2001, pp. 28-29; Halterman 2002, p. 25; Halterman 2003, p. 27; Halterman 2004, p. 42; Halterman 2005, p. 32; Halterman 2006, p. 34). In the intermountain west (Idaho, Utah, Colorado), the western yellow-billed cuckoo breeds in similar habitats as described above but are more scattered and in lower density (Parrish

et al.

1999, pp. 196-197; Taylor 2000, pp. 252-253; Idaho Fish and Game 2005, entire; Wiggins 2005, p. 15). Optimal breeding habitat in rangewide riparian breeding habitat contains willow-dominated groves with dense canopy closure and well-foliaged branches for nest building with nearby foraging areas consisting of a mixture of cottonwoods and willows with a high volume of healthy foliage.

In a study on the lower Colorado River, yellow-billed cuckoos nested in cottonwoods (n = 95, 57.5 percent), Goodding's willows (n = 49, 29.7

percent), honey mesquite (

Prosopis glandulosa

) (n = 13, 7.9 percent), tamarisk (n = 5, 3.0 percent), coyote willow (n = 2, 1.2 percent), and seep willow (n = 1, 0.7 percent) (Parametrix, Inc. and Southern Sierra Research Station 2019, Table 24 p. 89). Trees or shrubs used as nest substrates ranged in height from 2.5 m (8.2 ft) to 25.0 m (82 ft) (mean = 12.3 m (40.4 ft)). Nest heights ranged from 1 m (3.3 ft) to 20 m (66 ft) (mean = 7.6 m (24.8 ft)) (Parametrix, Inc. and Southern Sierra Research Station 2019, pp. ES-3, 88). Cottonwood, willow, and mesquite were planted. Tamarisk was not planted and is uncommon within the revegetation sites.

Some historical records document western yellow-billed cuckoo presence during the breeding season in extensive mesquite bosques on the Santa Cruz River and in the semi-desert grasslands and desert scrub xeroriparian drainages of Canelo Hills; and in the Madrean evergreen woodlands mountain drainages of the Atascosa, Pajarito, Santa Rita, Patagonia, Huachuca, and Chiricahua Mountains of Southeastern Arizona (Groschupf (1987, pp. 11, 14, 16; Corman and Magill 2000, pp. 26-29, 37). In Arizona in the late 1990s, western yellow-billed cuckoos were documented in Sycamore Canyon and Pena Blanca Canyon in the Atascosa Mountains, Canelo Hills, and in the desert scrub and grassland xeroriparian drainages in the Altar Valley on Buenos Aires National Wildlife Refuge (Corman and Magill (2000, pp. 38, 40-44, 48, 51). The first oak nest documented in a Madrean evergreen woodland drainage was found in the lower Santa Rita Mountains in 2014 (Tucson Audubon 2015, p. 44).

In a study to confirm western yellow-billed cuckoo breeding in ephemeral xeroriparian drainages in Madrean evergreen woodland, desert and semi-desert scrub, and semi-desert grassland habitats, 18 nests were found in 15 drainages in the lower Santa Catalina, lower Santa Rita, Patagonia, and lower Atascosa Mountains; and in the bajadas and foothill drainages of Buenos Aires National Wildlife Refuge (Sferra

et al.

2019, pp. 9-10). Trees where nests were placed varied in size and amount of cover, ranging from small to large trees and from well-concealed nests to partially exposed nests (Service 2018, entire). All but one nest was located along the drainage bottoms (See section on southwestern breeding (nesting) habitat for general Madrean evergreen woodland breeding habitat characteristics).

Therefore, we identify rangewide riparian woodland generally containing willow and cottonwood, usually within floodplains greater than 200 ac (81 ha) in extent and greater than 325 ft (100 m) in width, with one or more densely foliaged nesting areas, to be a physical or biological feature essential to the conservation of the species. In some areas, we also identify southwestern breeding habitat (riparian habitat (including xeroriparian and mesquite bosques), desert scrub and desert grassland drainages with a tree component, and Madrean evergreen woodland drainages) that may be less than the 200 ac (81 ha) area, 325 ft (100 m) width with one or more nesting and foraging sites to be a physical or biological feature essential to the conservation of the species.

Effects of climate change.

The available information on the effects of climate change has led us to predict that there will be altered environmental conditions across the western United States (the breeding range of the western yellow-billed cuckoo) (Hoerling

et al.

2012, pp. 3-15). In the southwestern United States, northern Mexico, California, Intermountain West, and Pacific Northwest, climate change information is generally leading us to predict an overall warmer, drier climate, with periodic episodic precipitation events that, depending on site conditions, are expected to have adverse effects on habitat of the western yellow-billed cuckoo (Enquist

et al.

2008, pp. 1-32; Gardali

et al.

2012, pp. 8-10; Munson

et al.

2012, pp. 1,083-1,095). In rivers that depend on snowmelt, these changes are expected to result in more winter flooding and reduced summer stream flows (Dominguez

et al.

2012, pp. 1-7). The amount of surface and groundwater available to regenerate and sustain riparian forests is expected to decline overall with persistent drought, favor the spread of tamarisk and other nonnative vegetation, and increase fire frequency (Westerling

et al.

2006, pp. 942-943; McCarthy 2012, pp. 23-25).

Precipitation events under most climate change scenarios within the range of the DPS will decrease in frequency and increase in severity (Dominguez

et al.

2012, pp. 4-7; Melillo

et al.

2014, pp. 70-81). Impacts to habitat from climate change will exacerbate impacts from impoundments, channelization, and alteration of river flows across the western United States and Mexico, and from conversion of habitat from native to mostly nonnative vegetation (Glenn and Nagler 2005, p. 439; Bradley

et al.

2009, pp. 1514-1519; IPCC 2014, pp. 4-11).

Changing climate is expected to place added stress on the species and its habitat. This change may reduce available nesting sites and patch size and affect prey abundance as a result of lower humidity in riparian areas from reduced moisture retention, through periods of prolonged desiccation, and through increased likelihood of scouring flood events (Melillo

et al.

2014, p. 75). In addition, evidence shows that climate change may disrupt the synchrony of nesting western yellow-billed cuckoos and their food supply, causing further population decline and curtailment of its occupied range (Durst 2004, pp. 40-41; Scott

et al.

2004, p. 70; Visser and Both 2005, pp. 2,561-2,569). For a more thorough discussion of climate change and the impacts it has on habitat for the western yellow-billed cuckoo, see the final rule to list the species as threatened published in the

Federal Register

on October 3, 2014 (79 FR 59992 at 60023).

Physical or Biological Features for the Western Yellow-Billed Cuckoo

According to 50 CFR 424.12(b)(1)(ii), we identify physical and biological features essential to the conservation of the species at an appropriate level of specificity using the best available scientific data. This analysis will vary between species and may include consideration of the appropriate quality, quantity, and spatial and temporal arrangements of such features in the context of the life history, status, and conservation needs of the species.

Based on our current knowledge of the habitat characteristics required to sustain the species' life-history processes including breeding, foraging, and dispersing, we propose to determine that the specific physical or biological features essential to the conservation of the western yellow-billed cuckoo are composed of three components below:

Physical or Biological Feature 1—Riparian woodlands; mesquite woodlands (mesquite-thorn-forest), and Madrean evergreen woodland drainages. This physical or biological feature includes breeding habitat found throughout the DPS range as well as additional breeding habitat characteristics unique to the Southwest.

a.

Rangewide breeding habitat (including areas in the Southwest).

Rangewide breeding habitat is composed of woodlands within floodplains or in upland areas or terraces often greater than 325 ft (100 m) in width and 200 ac (81 ha) or more in extent with an overstory and understory vegetation component in contiguous or nearly contiguous patches adjacent to intermittent or perennial watercourses. The slope of the watercourses is

generally less than 3 percent but may be greater in some instances. Nesting sites within the habitat have an above-average canopy closure (greater than 70 percent), and have a cooler, more humid environment than the surrounding riparian and upland habitats.

b.

Southwestern breeding habitat.

Southwestern breeding habitat is composed of more arid riparian woodlands (including mesquite bosques), desert scrub and desert grassland drainages with a tree component, and Madrean evergreen woodlands (oak and other tree species), in perennial, intermittent, and ephemeral drainages. These more arid riparian woodland drainages also bisect other habitat types, including Madrean evergreen woodland, native and nonnative desert grassland, and desert scrub. More than one habitat type within and adjacent to the drainage may contribute toward nesting habitat. Southwestern breeding habitat is more water-limited, contains a greater proportion of xeroriparian and nonriparian plant species, and is often narrower, more open, patchier, or sparser than elsewhere in the DPS and may persist only as narrow bands or scattered patches along the bankline or as small in-channel islands. The habitat contains a tree or large-shrub component with a variable overstory canopy and understory component that is sometimes less than 200 ac (81 ha). Riparian trees (including xeroriparian) in these ecosystems may even be more sparsely distributed and less prevalent than nonriparian trees. Adjacent habitat may include managed (mowed) nonnative vegetation or terraces of mesquite or other drought-tolerant species within the floodplain. In narrow or arid ephemeral drainages, breeding habitat commonly contains a mix of nonriparian vegetation found in the base habitat as well as riparian (including xeroriparian) trees.

Physical or Biological Feature 2—Adequate prey base. Presence of prey base consisting of large insect fauna (for example, cicadas, caterpillars, katydids, grasshoppers, large beetles, dragonflies, moth larvae, spiders), lizards, and frogs for adults and young in breeding areas during the nesting season and in post-breeding dispersal areas.

Physical or Biological Feature 3—Hydrologic processes, in natural or altered systems, that provide for maintaining and regenerating breeding habitat. This physical or biological feature includes hydrologic processes found in rangewide breeding habitat as well as additional hydrologic processes unique to the Southwest in southwestern breeding habitat:

a.

Rangewide breeding habitat hydrologic processes (including the Southwest):

Hydrologic processes (either natural or managed) in river and reservoir systems that encourage sediment movement and deposits and promote riparian tree seedling germination and plant growth, maintenance, health, and vigor (

e.g.,

lower-gradient streams and broad floodplains, elevated subsurface groundwater table, and perennial rivers and streams). In some areas where habitat is being restored, such as on terraced slopes above the floodplain, this may include managed irrigated systems that may not naturally flood due to their elevation above the floodplain.

b.

Southwestern breeding habitat hydrologic processes:

In southwestern breeding habitat, elevated summer humidity and runoff resulting from seasonal water management practices or weather patterns and precipitation (typically from North American Monsoon or other tropical weather events) provide suitable conditions for prey species production and vegetation regeneration and growth. Elevated humidity is especially important in southeastern Arizona, where cuckoos breed in intermittent and ephemeral drainages.

Because the western yellow-billed cuckoo exists in noncontiguous areas across a wide geographical and elevational range and its habitat is subject to dynamic events, the areas described below are essential to the conservation of the western yellow-billed cuckoo because they provide opportunities for breeding, allow for connectivity between habitat, assist in dispersal, provide redundancy to protect against catastrophic loss, and provide representation of the varying habitat types used for breeding, thereby helping to sustain the species. The physical or biological features essential to the conservation of the western yellow-billed cuckoo are present in the areas proposed to be designated, but the specific quality of habitat for nesting, migration, and foraging will vary in condition and location over time due to plant succession and the dynamic environment in which they exist. As a result, the areas that are proposed for designation may not contain at any one time all of the physical and biological features that have been identified for the western yellow-billed cuckoo, but all areas contain at least one.

We define revised proposed critical habitat as areas that contain at least physical or biological feature number 1 (including mesquite bosques); desert scrub and desert grassland drainages with a tree component; or Madrean evergreen woodland drainages. Based on use of the areas as breeding, we conclude that all of the areas identified contain all or most of the physical or biological features, but in some cases, these features are less prevalent, or their presence is variable over time due to the changing nature of habitat from hydrologic processes. As stated above, all critical habitat units within the revised proposed critical habitat are considered to have been occupied at the time of listing.

Special Management Considerations or Protection

When designating critical habitat, we assess whether the specific areas within the geographical area occupied by the species at the time of listing contain features that are essential to the conservation of the species and which may require special management considerations or protection. Here we describe the type of special management considerations or protection that may be required for the physical or biological features identified for the western yellow-billed cuckoo above. The specific critical habitat units and subunits where these management considerations or protection are identified in table 2 below.

A detailed discussion of activities influencing the western yellow-billed cuckoo and its habitat can be found in the final listing rule (79 FR 59992, October 3, 2014). The above-described physical or biological features (PBFs) may require special management considerations or protection to reduce the following threats or potential threats: Disruption of hydrologic processes that are necessary to maintain a healthy riparian system; unauthorized or uncontrolled grazing; loss of habitat from development activities and extractive uses (sand or gravel extraction); degradation of habitat as a result of expansion of nonnative vegetation; destruction of habitat by uncontrolled wildfire; reduction of prey insect abundance by the unauthorized or improper application of pesticides; removal of habitat by biocontrol insects; and habitat loss and degradation from invasive nonnative pest insects. More specific activities which may need special management are identified in table 2, below.

Special management considerations or protection are required within critical habitat areas to address these threats. Management activities that could ameliorate these threats include (but are not limited to) the following: Monitoring and regulating stream flows below reservoirs to mimic natural

flooding and other hydrologic processes to help maintain habitat; establishing permanent conservation easements or land acquisition to protect the species and its habitat; minimizing habitat disturbance, fragmentation, and destruction through use of best management practices; and providing appropriate buffers around western yellow-billed cuckoo habitat.

Changes Between Previous Proposal and Current Revised Proposal

On August 15, 2014, we proposed approximately 546,335 ac (221,094 ha) in 80 units for the western yellow-billed cuckoo (79 FR 48548). We are now proposing approximately 493,665 ac (199,779 ha) in 72 units as critical habitat in Arizona, California, Colorado, Idaho, New Mexico, Texas, and Utah. Approximately 164,248 ac (66,484 ha) of areas previously proposed as critical habitat are no longer being proposed as critical habitat (30 percent reduction of previous proposal). Based on new information and our conservation strategy, we are also proposing new areas totaling approximately 26,061 ac (10,547 ha) (5 percent). The remainder 467,604 ac (189,233 ha) are areas we previously proposed in 2014. This change and other changes below were partly the result of comments and information received on the previous proposal (from peer reviewers; Federal, State, and local land management agencies; and the public), corrections, and our reevaluation of the areas considered as essential to the conservation of the species. The comments and information received on the 2014 proposal are available online at

https://www.regulations.gov/docket?D=FWS-R8-ES-2013-0011.

Summaries of more specific changes are outlined below.

(1)

Revision of the Physical or Biological Features:

As outlined above in the Critical Habitat section, we revised our definition of the physical or biological features essential to the conservation of the species to describe and incorporate more accurately the habitat used by the western yellow-billed cuckoo for breeding, especially in the monsoonal breeding habitat. These changes were made as a result of comments received on habitat use of the western yellow-billed cuckoo and a reevaluation of the types of habitat used and habitat requirements of the western yellow-billed cuckoo across its range, specifically in regard to western yellow-billed cuckoos using monsoonal type habitats in addition to what has been considered more typical riparian habitats. Because of the variable ecological conditions, characteristics, and use of habitat by the western yellow-billed cuckoo across the species' range, information obtained from the comments received indicated that we needed to be more specific about the habitat differences and habitat requirements for the species and include that range of habitat in the revised proposal (see Physical or Biological Features for the Western Yellow-Billed Cuckoo).

(2)

Reevaluation of Conservation Strategy for Determining Critical Habitat:

In development of this revised proposed designation, we reevaluated our conservation strategy for determining which areas to consider as critical habitat for the western yellow-billed cuckoo to better reflect the biological information and conservation needs of the species (see

Conservation Strategy and Selection Criteria Used To Identify Critical Habitat

). In our reevaluation we took into account the importance of the Southwest as the main breeding area for the western yellow-billed cuckoo as well as including areas of differing habitat and distribution.

(3)

Landownership Identification:

We received numerous comments from Federal, State, local, and private landowners regarding discrepancies in land ownership identifications. In response to these comments, we have attempted to the best of our ability to reconcile these discrepancies by using information provided in the docket or using newer land ownership information where available. We are currently asking for any updated landownership information during the public comment period for this proposed rule (see Ownership Mapping Considerations).

Revised Proposed Critical Habitat Designation

We are proposing 72 units as critical habitat for the western yellow-billed cuckoo. The critical habitat areas we describe below constitute our current best assessment of areas that meet the definition of critical habitat for the western yellow-billed cuckoo. Table 1 below identifies the units (in acres (hectares)) within the geographical area occupied by the species at the time of listing that contain the physical or biological features that support multiple life-history processes for the western yellow-billed cuckoo. Land areas identified as “Other” include county, city, unclassified, or unknown land ownerships.

Table 1—Revised Proposed Critical Habitat Units for Western Yellow-Billed Cuckoo

Unit name

Unit

Federal

AC

HA

State

AC

HA

Tribal

AC

HA

Other

AC

HA

Total

AC

HA

CA-AZ 1 Colorado River 1

1

31,351

12,687

4,207

1,702

22,315

9,031

24,265

9,820

82,138

33,240

CA-AZ 2 Colorado River 2

2

15,189

6,146

2

1

4,732

1,915

3,668

1,484

23,589

9,546

AZ 1 Bill Williams River

3

2,640

1,068

749

303

3,389

1,371

AZ 2 Alamo Lake

4

1,840

745

953

386

2,793

1,130

AZ 3 Hassayampa River

5

12

5

896

362

908

367

AZ 4 Agua Fria River

6

1,802

729

235

95

1,300

527

3,336

1,350

AZ 5 Upper Verde Creek

7

2,504

1,013

821

332

191

77

2,531

1,024

6,047

2,447

AZ 6 Oak Creek

8

596

241

160

65

1,475

597

2,231

903

AZ 7 Beaver Creek

9

1,491

603

3

1

588

238

2,082

842

AZ 8 Lower Verde/West Clear Ck

10

570

231

32

13

43

17

1,534

621

2,178

882

AZ 9A Horseshoe Dam

11

2,743

1,110

2,743

1,110

AZ 9B Horseshoe Dam

11

1,194

483

37

15

1,231

498

AZ 10 Tonto Creek

12

2,529

1,023

1,141

462

3,669

1,485

AZ 11 Pinal Creek

13

30

12

389

157

419

169

AZ 12 Bonita Creek

14

828

335

101

40

928

375

AZ 13 San Francisco River

15

1,192

482

135

55

1,327

537

AZ 14 Upper San Pedro River

16

17,958

7,267

1,903

770

11,199

4,532

31,060

12,569

AZ 15 Lower San Pedro/Gila River

17

2,957

1,197

2,282

925

729

295

17,431

7,055

23,400

9,470

AZ 16 Sonoita Creek

18

926

375

1,563

632

2,488

1,007

AZ 17 Upper Cienega Creek

19

4,630

1,874

574

232

5,204

2,106

AZ 18 Santa Cruz River

20

505

204

4

2

9,034

3,656

9,543

3,862

AZ 19 Black Draw

21

896

362

134

54

570

231

1,599

647

AZ 20 Gila River 1

22

779

315

215

87

10,183

4,121

9,547

3,863

20,724

8,387

AZ 21 Salt River

23

2,469

999

121

49

2,590

1,048

AZ 22 Lower Cienega Creek

24

759

307

1,601

648

2,360

955

AZ 23 Blue River

25

1,025

415

1,025

415

AZ 24 Pinto Creek South

26

368

149

5

2

373

151

AZ 25 Aravaipa Creek

27

622

252

116

47

392

159

2,199

890

3,329

1,347

AZ 26 Gila River 2

28

1,953

791

206

83

1,436

581

4,994

2,021

8,588

3,475

AZ 27 Pinto Creek North

29

415

168

12

5

427

173

AZ 28 Mineral Creek

30

1

0

198

80

180

73

380

154

AZ 29 Big Sandy River

31

5,269

2,132

1,453

588

236

96

13,221

5,351

20,179

8,166

NM 1 San Francisco River

32

738

299

10

4

1,291

522

2,039

825

NM 2 Gila River

33

974

394

201

81

3,002

1,215

4,177

1,690

NM 3A Mimbres River

34

260

105

260

105

NM 3B Mimbres River

34

285

115

284

115

NM 4 Upper Rio Grande 1

35

1,313

531

517

209

1,830

741

NM 5 Upper Rio Grande 2

36

1,173

475

1,173

475

NM 6A Middle Rio Grande

37

7

3

6,273

2,539

958

388

7,238

2,929

NM 6B Middle Rio Grande

37

11,802

4,776

21,907

8,865

2,257

913

25,376

10,270

61,343

24,825

NM 7 Upper Gila River

38

1,086

440

188

76

3,453

1,397

4,727

1,913

NM 8A Caballo Delta North

39

190

77

190

77

NM 8B Caballo Delta South

39

155

63

155

63

NM 9 Animas

40

608

246

608

246

NM 10 Selden Cyn/Radium Springs

41

20

8

218

88

237

96

AZ 30 Arivaca Wash/San Luis

42

4,662

1,887

89

36

1,014

410

5,765

2,333

AZ 31 Florida Wash

43

449

182

255

103

43

18

747

302

AZ 32 California Gulch

44

376

152

182

73

558

226

AZ 33 Sycamore Canyon

45

601

243

0

0

601

243

AZ 34 Madera Canyon

46

1,419

574

313

127

1,732

701

AZ 35 Montosa Canyon

47

496

201

3

1

499

202

AZ 36 Patagonia Mountains

48

1,059

429

8

3

845

341

1,912

774

AZ 37 Canelo Hills

49

1,381

559

1

1

1,440

583

2,822

1,142

AZ 38 Arivaca Lake

50

567

229

417

169

381

154

1,365

553

AZ 39 Peppersauce Canyon

51

317

128

32

13

349

141

AZ 40 Pena Blanca Canyon

52

483

196

484

196

AZ 41 Box Canyon

53

317

128

184

74

34

14

536

217

AZ 42 Rock Corral Canyon

54

190

77

25

10

214

87

AZ 43 Lyle Canyon

55

716

290

577

234

1,293

523

AZ 44 Parker Canyon Lake

56

1,424

576

75

31

1,499

607

AZ 45 Barrel Canyon

57

755

306

164

66

920

372

AZ 46 Gardner Canyon

58

4,320

1,748

290

117

471

191

5,081

2,056

AZ 47 Brown Canyon

59

726

294

228

92

159

65

1,113

451

AZ 48 Sycamore Canyon/Patagonia

60

604

245

604

245

AZ 49 Washington Gulch

61

361

146

226

91

587

237

AZ 50 Paymaster Spring/Mowry

62

390

158

512

207

903

365

CA 1 Sacramento River

63

2,123

859

485

197

32,800

13,274

35,406

14,328

CA 2 South Fork Kern River

64

88

35

419

170

2,133

863

2,640

1,068

ID 1 Snake River 1

65

3,694

1,494

1,763

713

2,527

1,023

1,672

676

9,655

3,907

ID 2 Snake River 2

66

5,862

2,372

1,940

785

3,641

1,473

11,442

4,630

ID 3 Henry's Fork/Teton Rivers

67

756

305

511

206

3,374

1,366

4,641

1,878

CO 1 Colorado River

68

32

13

417

169

3,553

1,438

4,002

1,620

CO 2 North Fork Gunnison

69

115

47

2,211

895

2,326

941

UT 1 Green River 1

70

4,657

1,885

4,411

1,785

14,611

5,913

4,702

1,903

28,381

11,486

UT 2 Green River 2

71

40

17

632

256

462

187

1,135

459

TX 1 Terlingue Creek/Rio Grande

72

7,792

3,153

121

49

7,913

3,202

Totals

168,095

68,023

48,615

19,673

68,414

27,687

208,547

84,397

493,665

199,779

Note:

Area sizes do not sum due to rounding.

We also provide information on special management considerations or protection that may be required for the physical or biological features essential to the conservation of the species within each of those units. The special management considerations include actions to address the main threats to western yellow-billed cuckoo habitat and are grouped into three categories: (1) Threats from alteration of hydrology; (2) threats from floodplain encroachment; and (3) other identified threats. These threats and special management considerations are summarized in table 2. See end of table for definition of codes.

Table 2—Threats to Habitat and Potential Special Management Considerations

Unit

Name of unit

Threats from

alteration of

hydrology

Threats from

floodplain

encroachment

Other threats

Special mgt.

1

CA/AZ-1 Colorado River 1

A, B, C

E, F, G, H, I, J

K, L, M, N, P

R, S, T.

2

CA/AZ-2 Colorado River 2

A, B, C

E, F, G, H, I, J

K, L, M, N, P

R, S, T.

3

AZ-1 Bill Williams River

A, B, C

K, M, N, P

R, T.

4

AZ-2 Alamo Lake

B, C, D

F

K, M, N, P, Q

R, S, T.

5

AZ-3 Hassayampa River

B, C

E, F, G, H, I, J

K, L, M, N, P

R, S, T.

6

AZ-4 Agua Fria River

A, B, C

F, G, I

K, L, M, N, P

R, S, T.

7

AZ-5 Upper Verde River

B, C

F, G, I

K, M, N, P

R, S, T.

8

AZ-6 Oak Creek

B, C

F, G, I

K, M, N, P, Q

R, S, T.

9

AZ-7 Beaver Creek

B, C

F, G, I

K, M, N, P

R, S, T.

10

AZ-8 Lower Verde R./West Clear Creek

A, B, C

F, G, I

K, M, N, P

R, S, T.

11

AZ-9A Horseshoe Dam

A, B, C, D

I

K, M, N,P,Q

R, S, T.

11

AZ-9B Horseshoe Dam

A, B, C, D

I

K, M, N,P,Q

R, S, T.

12

AZ-10 Tonto Creek

B, C, D

F, G, I

K, M, N, P, Q

R, S, T.

13

AZ-11 Pinal Creek

B, C

F, G, I, J

K, L, M, N, P

R, S, T.

14

AZ-12 Bonita Creek

B, C

F, I

K, M, N, P, Q

R, S, T.

15

AZ-13 San Francisco River

B, C

F, I

K, M, N, P

R, S, T.

16

AZ-14 Upper San Pedro River

B, C

E, F, G, I

K, L, M, N, P, Q

R, S, T.

17

AZ-15 Lower San Pedro and Gila Rivers

A, B, C

E, F, G, H, I

K, L, M, N, P

R, S, T.

18

AZ-16 Sonoita Creek

B, C, D

F, G, I

K, M, N, P, Q

R, S, T.

19

AZ-17 Upper Cienega Creek

B, C

F, G, I

K, M, N, O, P, Q

R, S, T.

20

AZ-18 Santa Cruz River

B, C

E, F, G, H, I

K, L, M, N, P

R, S, T.

21

AZ-19 Black Draw

B, C

F

K, M, N, P

R, S, T.

22

AZ-20 Gila River 1

A, B, C

E, F, G, H

K, L, M, N, P

R, S, T.

23

AZ-21 Salt River

A, B, C, D

F, G, I

K, M, N, P

R, S, T.

24

AZ-22 Lower Cienega Creek

B, C

E, F, G, I, J

K, L, M, N, O, P

R, S, T.

25

AZ-23 Blue River

A, B, C

G, I, J

K, M, N, P

R, S, T.

26

AZ-24 Pinto Creek South

A, B, C

F, G, I, J

K, N, P

R, S, T.

27

AZ-25 Aravaipa Creek

B, C

E, F, I, J

K, M, N, P

R, S, T.

28

AZ-26 Gila River 2

A, B, C

F, G, I, J

K, N, P

R, S, T.

29

AZ-27 Pinto Creek North

B, C

F, I, J

K, N, P

R, S, T.

30

AZ-28 Mineral Creek

B, C

E, F

K, O, P, Q

R, S, T.

31

AZ-29 Big Sandy River

B, C

E, F,G, I,

K, L, N, P, Q

R, S, T.

32

NM-1 San Francisco River

B, C

E, F, G, H, I

K, L, M, N

R, S, T.

33

NM-2 Gila River

B, C

E, F, G, I, J

K, L, M, N

R, S, T.

34

NM-3A Mimbres River

B, C

F, I

K, M, N

R, S, T.

34

NM-3B Mimbres River

B, C

F, I

K, M, N

R, S, T.

35

NM-4 Upper Rio Grande 1

A, B, C

E, F, G, H, I

K, L, M, N

R, S, T.

36

NM-5 Upper Rio Grande 2

A, B, C

E, F, G, H, I, J

K, L, M, N

R, S, T.

37

NM-6A Middle Rio Grande

A, B, C, D

E, F, G, H, I, J

K, L, M, N

R, S, T.

37

NM-6B Middle Rio Grande

A, B, C, D

E, F, G, H, I, J

K, L, M, N

R, S, T.

38

NM-7 Upper Gila River

B, C

E, F, G, I, J

K, L, M, N

R, S, T.

39

NM-8A Caballo Delta North

A, B, C, D

E, F, G, I

K, L, M, N, O, P, Q

R, S, T.

39

NM-8B Caballo Delta South

A, B, C, D

E, F, G, I

K, L, M, N, O, P, Q

R, S, T.

40

NM-9 Animas

B, C

F

O, P

T.

41

NM-10 Selden Canyon and Radium Springs

A, B, C

E, F, G, H, I

L, M, N, O, P, Q

R, S, T.

42

AZ-30 Arivaca Wash and San Luis Wash

B, C

F, I

K, M, N, P

R, S, T.

43

AZ-31 Florida Wash

B, C

E, F, G, I, J

K, M, N, P

R, S, T.

44

AZ-32 California Gulch

B, C

F, G, I

K, M, N, O, P, Q

R, S, T.

This text is long and has been trimmed here. Open the source document for the complete record.