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[August 16, 2014]
Fish & Wildlife Service Seeks Comments on Designation for Western Distinct Population Segment of Yellow-Billed Cuckoo
(Targeted News Service Via Acquire Media NewsEdge) Targeted News Service WASHINGTON, Aug. 15 -- The U.S. Fish & Wildlife Service published the following proposed rule in the Federal Register: Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Western Distinct Population Segment of the Yellow-Billed Cuckoo A Proposed Rule by the Fish and Wildlife Service on 08/15/2014 Publication Date: Friday, August 15, 2014 Agencies: Department of the Interior Fish and Wildlife Service Dates: We will accept comments received or postmarked on or before October 14, 2014. Comments submitted electronically using the Federal Comments Close: 10/14/2014 Entry Type: Proposed Rule Action: Proposed rule.
Document Citation: 79 FR 48547 Page: 48547 -48652 (106 pages) CFR: 50 CFR 17 Agency/Docket Numbers: Docket No. FWS-R8-ES-2013-0011 4500030114 RIN: 1018-AZ44 Document Number: 2014-19178 Shorter URL:
Action Proposed Rule.
Summary We, the U.S. Fish and Wildlife Service (Service), propose to designate 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 546,335 acres (221,094 hectares) are being proposed for designation as critical habitat in Arizona, California, Colorado, Idaho, Nevada, New Mexico, Texas, Utah, and Wyoming. The effect of this regulation, if finalized, is to designate critical habitat for the western yellow-billed cuckoo under the Endangered Species Act.
DATES: We will accept comments received or postmarked on or before October 14, 2014. Comments submitted electronically using the Federal eRulemaking Portal (see ADDRESSES section, 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 the FOR FURTHER INFORMATION CONTACT section by September 29, 2014.
ADDRESSES: You may submit comments by one of the following methods: (1) Electronically: Go to the Federal eRulemaking Portal:
. 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: BPHC, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
We request that you send comments only by the methods described above. We will post all comments on
. 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 are included in the administrative record for this rulemaking and are available at
at Docket No. FWS-R8-ES-2013-0011, and at the Sacramento Fish and Wildlife Office at
(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 Fish and Wildlife Service Web site and field office set out above, and may also be included in the preamble of this rule or at
FOR FURTHER INFORMATION CONTACT: Jen Norris, Field Supervisor, U.S. Fish and Wildlife Service, Sacramento Fish and Wildlife Office, 2800 Cottage Way, Room W-2605, Sacramento, California 95825; by telephone 916-414-6600; or by facsimile 916-414-6712. If you use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-877-8339.
SUPPLEMENTARY INFORMATION: Executive Summary Why we need to publish a rule. Under the Endangered Species Act, 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, 2013, we proposed listing the western yellow-billed cuckoo as a threatened species (78 FR 61621).
Section 4(b)(2) of the Act states that the Secretary shall designate critical habitat on the basis of the best available scientific data after taking into consideration the economic impact, national security impact, and any other relevant impact of specifying any particular area as critical habitat. 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.
This is a proposed rule to designate critical habitat for the western yellow-billed cuckoo. This proposed designation of critical habitat identifies areas based on the best scientific and commercial information available that we have determined are essential to the conservation of the species. The proposed critical habitat is located in the States of Arizona, California, Colorado, Idaho, Nevada, New Mexico, Texas, Utah, and Wyoming.
We have prepared a draft economic analysis of the proposed designation of critical habitat. In order to consider economic impacts, we have prepared an analysis of the economic impacts of the proposed critical habitat designation and related factors. The supporting information we used in determining the economic impacts of the proposed critical habitat is summarized in this proposed rule (see Consideration of Economic Impacts) and is available at
at Docket No. FWS-R8-ES-2013-0011 and at the Sacramento Fish and Wildlife Office at
(see FOR FURTHER INFORMATION CONTACT).
We are seeking peer review and public comment. We are seeking comments and soliciting information from knowledgeable individuals with scientific expertise to review our analysis of the best available science and application of that science and to provide any additional scientific information to improve this proposed rule. Because we will consider all comments and information we receive during the comment period, our final determination may differ from this proposal.
Information Requested We intend that any final action resulting from this proposed rule will be based on the best scientific and commercial data available and be as accurate and as effective as possible. Therefore, we request comments or information from other concerned governmental agencies, Native American tribes, the scientific community, industry, or any other interested parties concerning this proposed rule. 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) The reasons why we should or should not designate habitat as "critical habitat" under section 4 of the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.) (Act), including whether there are threats to the western yellow-billed cuckoo from human activity that can be expected to increase due to the designation, and whether that increase in threat outweighs the benefit of designation such that the designation of critical habitat may not be prudent.
(3) Specific information on: (a) The amount and distribution of western yellow-billed cuckoo habitat; (b) What areas occupied at the time of listing (i.e., are currently occupied), that contain features essential to the conservation of the western yellow-billed cuckoo, should be included in the critical habitat designation and why; (c) 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; and (d) What areas not occupied at the time of listing are essential for the conservation of the western yellow-billed cuckoo and why.
(4) For Unit 52 (NM-8 Middle Rio Grande 1; New Mexico), we have determined that it is appropriate to propose critical habitat into the conservation pool area of Elephant Butte Reservoir down to approximately river-mile (RM) 54. This is based on the number of yellow-billed cuckoo breeding pairs identified in the area, the amount of habitat available, and the relationship and importance of the Elephant Butte Reservoir and Rio Grande River to other yellow-billed cuckoo habitat in New Mexico and the southwest. Additional habitat and western yellow-billed cuckoo breeding occurrences are located downstream to approximately RM 42. We seek information on whether the area or portions of the area to RM 42 at Elephant Butte Reservoir in New Mexico is essential to the conservation of the species and whether we should include the area as critical habitat for the species and why.
(5) 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 for those specific areas whether the benefits of potentially excluding them outweigh the benefits of including them, pursuant to section 4(b)(2) of the Act. For specific lands that we should consider for exclusion under section 4(b)(2) of the Act, please provide us management plans, conservation easements, agreements, habitat conservation plans (HCP), or other appropriate information, that describe the commitment and assurances of protection of the physical or biological features of western yellow-billed cuckoo critical habitat; property boundaries; western yellow-billed cuckoo status, distribution, and abundance; and management actions to protect the physical or biological features of the western yellow-billed cuckoo.
(6) Land use designations and current or planned activities in the subject areas, and their possible impacts on the proposed critical habitat.
(7) Information on the projected and reasonably likely impacts of climate change on the western yellow-billed cuckoo and proposed critical habitat.
(8) 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.
(9) 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 information with your submission (such as scientific journal articles or other publications) to allow us to verify any scientific or commercial information you include.
You may submit your comments and materials concerning this proposed rule by one of the methods listed in the ADDRESSES section. We request that you send comments only by the methods described in the ADDRESSES section.
We will post your entire comment--including your personal identifying information--on
. 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 proposed rule, will be available for public inspection on
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 All previous Federal actions are described in the proposal 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). Please see that document for actions leading to this proposed designation of critical habitat.
Background It is our intent to discuss below only those topics directly relevant to the designation of critical habitat for the western yellow-billed cuckoo. For a thorough assessment of the species' biology and natural history, including limiting factors and species resource needs, please refer to the proposal to list this species as threatened published previously in the Federal Register on October 3, 2013 (78 FR 61621) (available at
at Docket No. FWS-R8-ES-2013-0104).
Critical Habitat Background Critical habitat is defined in section 3 of the Act as: (1) The specific areas within the geographical area occupied by the species, at the time it is listed in accordance with the Act, on which are found those physical or biological features (a) Essential to the conservation of the species and (b) Which may require special management considerations or protection; and (2) Specific areas outside the geographical area occupied by the species at the time it is listed, upon a determination that such areas are essential for the conservation of the species.
Conservation, as defined under section 3 of the Act, means to use and the use of all methods and procedures which are necessary to bring an endangered or threatened species to the point at which the measures provided pursuant to the Act are no longer necessary. Such methods and procedures include, but are not limited to, all activities associated with scientific resources management, such as research, census, law enforcement, habitat acquisition and maintenance, propagation, live trapping, and transplantation, and, in the extraordinary case where population pressures within a given ecosystem cannot be otherwise relieved, may include regulated taking.
Critical habitat receives protection under section 7 of the Act through the requirement that Federal agencies ensure, in consultation with the U.S. Fish and Wildlife Service, that any action they authorize, fund, or carry out is not likely to result in the destruction or adverse modification of critical habitat. The designation of critical habitat does not affect land ownership or establish a refuge, wilderness, reserve, preserve, or other conservation area. Such designation does not allow the government or public access to private lands. Such designation does not require implementation of restoration, recovery, or enhancement measures by non-Federal landowners. Where a landowner seeks or requests Federal agency funding or authorization for an action that may affect a listed species or critical habitat, the consultation requirements of section 7(a)(2) of the Act would apply. In the event of a destruction or adverse modification finding, the obligation of the Federal action agency and the landowner is not to restore or recover the species, but to implement reasonable and prudent alternatives to avoid destruction or adverse modification of critical habitat.
Under the first prong of the Act's definition of critical habitat, areas within the geographical area occupied by the species at the time it was listed are included in a critical habitat designation if they contain physical or biological features (1) essential to the conservation of the species, and (2) which may require special management considerations or protection. For these areas, critical habitat designations identify, to the extent known using the best scientific and commercial data available, those physical or biological features essential to the conservation of the species (such as space, food, cover, and protected habitat). In identifying those physical and biological features within an area, we focus on the principal biological or physical constituent elements (primary constituent elements such as roost sites, nesting grounds, seasonal wetlands, water quality, tide, soil type) that are essential to the conservation of the species. Primary constituent elements are those specific elements of the physical or biological features that provide for a species' life-history processes and are essential to the conservation of the species.
Under the second prong of the Act's definition of critical habitat, we can designate critical habitat in areas outside the geographical area occupied by the species at the time it is listed, upon a determination that such areas are essential for the conservation of the species. For example, an area currently occupied by the species but that was not occupied at the time of listing and which is outside the geographical area (range) considered occupied at the time of listing may be essential for the conservation of the species and may be included in the critical habitat designation. We designate critical habitat in areas outside the geographical area occupied by a species at the time of listing only when a designation limited to its range would be inadequate to ensure the conservation of the species.
Section 4 of the Act requires that we designate critical habitat on the basis of the best scientific and commercial data available. Further, our Policy on Information Standards Under the Endangered Species Act (published in the Federal Register on July 1, 1994 (59 FR 34271)), the Information Quality Act (section 515 of the Treasury and General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)), and our associated Information Quality Guidelines provide criteria, establish procedures, and provide guidance to ensure that our decisions are based on the best scientific data available. They require our biologists, to the extent consistent with the Act and with the use of the best scientific data available, to use primary and original sources of information as the basis for recommendations to designate critical habitat.
When we determine which areas should be designated as critical habitat, our primary source of information is generally the information developed during the listing process for the species. Additional information sources may include the recovery plan for the species, articles in peer-reviewed journals, conservation plans developed by States and counties, scientific status surveys and studies, biological assessments, or other unpublished materials and expert opinion or personal knowledge.
Habitat is dynamic, and species may move from one area to another over time. Climate change will be a particular challenge for biodiversity because the interaction of additional stressors associated with climate change and current stressors may push species beyond their ability to survive (Lovejoy 2005, pp. 325-326). The synergistic implications of climate change and habitat fragmentation are the most threatening facet of climate change for biodiversity (Hannah and Lovejoy 2005, p. 4). Current climate change predictions for terrestrial areas in the Northern Hemisphere indicate warmer air temperatures, more intense precipitation events, and increased summer continental drying (Field et al. 1999, pp. 1-3; Hayhoe et al. 2004, p. 12422; Cayan et al. 2005, p. 6; Intergovernmental Panel on Climate Change (IPCC) 2007, p. 1181). Climate change may lead to increased frequency and duration of severe storms and droughts (McLaughlin et al. 2002, p. 6074; Cook et al. 2004, p. 1015; Golladay et al. 2004, p. 504).
We recognize that critical habitat designated at a particular point in time may not include all of the habitat areas that we may later determine are necessary for the recovery of the species. For this reason, a critical habitat designation does not signal that habitat outside the designated area is unimportant or may not be needed for recovery of the species. Areas that are important to the conservation of the species, both inside and outside the critical habitat designation, will continue to be subject to: (1) Conservation actions implemented under section 7(a)(1) of the Act, (2) regulatory protections afforded by the requirement in section 7(a)(2) of the Act for Federal agencies to ensure their actions are not likely to jeopardize the continued existence of any endangered or threatened species, and (3) section 9 of the Act's prohibitions on taking any individual of the species, including taking caused by actions that affect habitat. Federally funded or permitted projects affecting listed species outside their designated critical habitat areas may still result in jeopardy findings in some cases. These protections and conservation tools will continue to contribute to recovery of this species. Similarly, critical habitat designations made on the basis of the best available information at the time of designation will not control the direction and substance of future recovery plans, habitat conservation plans (HCPs), or other species conservation planning efforts if new information available at the time of these planning efforts calls for a different outcome.
Physical or Biological Features In accordance with section 3(5)(A)(i) and 4(b)(1)(A) of the Act and regulations at 50 CFR 424.12, 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 essential to the conservation of the species, and which require special management considerations or protection. These include, but are not limited to: (1) Space for individual and population growth and for normal behavior; (2) Food, water, air, light, minerals, or other nutritional or physiological requirements; (3) Cover or shelter; (4) Sites for breeding, reproduction, or rearing (or development) of offspring; and (5) Habitats that are protected from disturbance or are representative of the historical, geographical, and ecological distributions of a species.
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 listing rule published in the Federal Register on October 3, 2013 (78 FR 61621). 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 stopover or dispersal habitat within the breeding range, but based on the best scientific evidence we conclude that these additional activities require the same types of habitat as breeding and foraging and that conservation of sufficient habitat for breeding and foraging will also provide sufficient habitat for the other activities. We have determined that the following physical or biological features are essential to the western yellow-billed cuckoo.
Space for Individual and Population Growth and for Normal Behavior The western yellow-billed cuckoo breeds in riparian habitat along low-gradient (surface slope less than 3 percent) rivers and streams, and in open riverine valleys that provide wide floodplain conditions (greater than 325 ft (100 m)). Within the boundaries of the distinct population segment (DPS) (see Figure 2 at 78 FR 61631, in the proposed listing rule (78 FR 61621; October 3, 2013)) these riparian areas are located from southern British Columbia, Canada, to southern Sinaloa, Mexico, and may occur from sea level to 7,000 feet (ft) (2,154 meters (m)) (or slightly higher in western Colorado, Utah, and Wyoming) in elevation. Because critical habitat only applies to areas within the United States, we did not examine areas in Canada and Mexico. The moist conditions that support riparian plant communities that provide western yellow-billed cuckoo habitat typically exist in lower elevation, broad floodplains, as well as where rivers and streams enter impoundments. The species does not use narrow, steep-walled canyons. In the extreme southern portion of their range in the States of Sonora (southern quarter) and Sinaloa, Mexico, western yellow-billed cuckoos also nest in upland thorn scrub and dry deciduous habitats away from the riparian zone (Russell and Monson 1988, p. 131), though their densities are lower in these habitats than they are in adjacent riparian areas.
At the landscape level, the available information suggests the western yellow-billed cuckoo requires large tracts of willow-cottonwood or mesquite (Prosopis sp.) forest or woodland for their nesting season habitat. Western yellow-billed cuckoos rarely nest at sites less than 50 acres (ac) (20 hectares (ha)) in size, and sites less than 37 ac (15 ha) are considered unsuitable habitat (Laymon and Halterman 1989, p. 275). Habitat patches from 50 to 100 ac (20 to 40 ha) in size are considered marginal habitat (Laymon and Halterman 1989, p. 275). Habitat between 100 ac (40 ha) and 200 ac (81 ha), although considered suitable are not consistently used by the species. The optimal size of habitat patches for the species are generally greater than 200 ac (81 ha) in extent and have dense canopy closure and high foliage volume of willows (Salix sp.) and cottonwoods (Populus sp.) (Laymon and Halterman 1989, pp. 274-275) and thus provide adequate space for foraging and nesting. Tamarisk (Tamarix sp.), a nonnative tree species, may be a component of the habitat, especially in Arizona and New Mexico. As the proportion of tamarisk increases, the suitability of the habitat for the western yellow-billed cuckoo decreases. Sites with a monoculture of tamarisk are unsuitable habitat for the species. Sites with strips of habitat less than 325 ft (100 m) in width are rarely occupied, which indicates that edge effects in addition to overall patch size influence western yellow-billed cuckoo habitat selection for nesting. The association of breeding with large tracts of suitable riparian habitat is likely related to home range size. Individual home ranges during the breeding season average over 100 ac (40 ha), and home ranges up to 500 ac (202 ha) have been recorded (Laymon and Halterman 1987, pp. 31-32; Halterman 2009, p. 93; Sechrist et al. 2009, p. vii; McNeil et al. 2010, p. 75; McNeil et al. 2011, p. 37; McNeil et al. 2012, p. 69).
Western yellow-billed cuckoos may nest at more than one location in a year. Some individuals may nest first in the northern area, such as Arizona or New Mexico, and then nest a second time at more southern locations in southern Sonora, Mexico (Rohwer et al. 2009, pp. 19050-19055). However, data are lacking to confirm that the same individuals are breeding in both locations within the same season. 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).
During movements between nesting attempts western yellow-billed cuckoos are 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). These stopover and foraging sites can be similar to breeding sites, but are smaller is size, are narrower in width, and lack understory vegetation when compared to nesting sites.
Therefore, based on the information above, we identify rivers and streams of lower gradient and more open valleys with a broad floodplain to be an essential physical or biological feature for this species.
Food, Water, Air, Light, Minerals, or Other Nutritional or Physiological Requirements Food Western yellow-billed cuckoos are insect specialists but also prey on small vertebrates such as tree frogs and lizards. They depend on an abundance of large, nutritious insect prey (for example, sphinx moth larvae (Family Sphingidae) and katydids (Family Tettigoniidae)) and, in some cases, a high population density of tree frogs (e.g., Hyla sp. and Pseudacris sp.). In the arid West, these conditions are usually found in cottonwood-willow riparian associations along water courses. The arrival of birds and the timing of nesting are geared to take advantage of any short-term abundance of prey. 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). Diet studies of western yellow-billed cuckoos on the South Fork Kern River in California showed the majority of the prey to be large green caterpillars (primarily big poplar sphinx moth larvae (Pachysphinx occidentalis)) (45 percent), tree frogs (24 percent), katydids (22 percent), and grasshoppers (Suborder Caelifera) (9 percent) (Laymon et al. 1997, p. 7). Minor prey at that and other sites include beetles (Coleoptera sp.), dragonflies (Odonata sp.), praying mantis (Mantidae sp.), flies (Diptera sp.), spiders (Araneae sp.), butterflies (Lepidoptera sp.), caddis flies (Trichoptera sp.), crickets (Gryllidae sp.), 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). Small vertebrates such as lizards (Lacertilia sp.) are also eaten (Hughes 1999, p. 8).
Western yellow-billed cuckoo food availability is largely influenced by the health, density, and species of vegetation. For example, the big poplar sphinx moth larvae are found only in willows and cottonwoods and appear to reach their highest density in Fremont cottonwoods (Oehlke 2012, p. 4). Desiccated riparian sites produce fewer suitable insects than healthy moist sites. Western yellow-billed cuckoos generally forage within the tree canopy, and the higher the foliage volume the more likely yellow-billed cuckoos are to use a site for foraging (Laymon and Halterman 1985, pp. 10-12). They generally employ a "sit and wait" foraging strategy, watching the foliage for movement of potential prey (Hughes 1999, p. 7).
Therefore, based on the information above, we identify the presence of abundant, large insect fauna (for example, cicadas, caterpillars, katydids, grasshoppers, large beetles, and dragonflies) and tree frogs during nesting season to be an essential physical or biological feature for this species.
Water and Humidity 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. 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 different types of regulated and unregulated flow conditions depending on the interaction of the water feature and the physical characteristics of the landscape.
Hydrologic conditions at western yellow-billed cuckoo breeding sites can vary remarkably between years. At some locations during low rainfall years, water or saturated soil is not available. At other locations, particularly at reservoir intakes, riparian vegetation can be inundated for extended periods of time in some years and be totally dry in other years. This is particularly true 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. This year-to-year change in hydrology can affect food availability and habitat suitability for western yellow-billed cuckoos. Extended inundation reduces habitat suitability because larvae of sphinx moths pupate and eggs of katydids are laid underground, and prolonged flooding kills the larvae and eggs (Peterson et al. 2008), thus removing important food sources.
In some areas, managed hydrologic cycles above or below dams can create temporary western yellow-billed cuckoo habitat, but may not be able to support it for an extended amount of time, or may support varying amounts of habitat at different points of the cycle and in different years. Water management operations create varied situations that allow different plant species to thrive when water is released below a dam, held in a reservoir, or removed from a lakebed, and consequently, 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 wet years, habitat within a lake and below a dam can be flooded for extended periods of time and vegetation can be stressed or killed. During dry years, vegetated habitat can be desiccated and stressed or killed because of lack of water.
Humid conditions created by surface and subsurface moisture appear to be important habitat parameters for western yellow-billed cuckoo. The species has been observed as being restricted to nesting in moist riparian habitat in the arid West because of humidity requirements for successful hatching and rearing of young (Hamilton and Hamilton 1965, pp. 427; Gaines and Laymon 1984, pp. 75-76; Rosenberg et al. 1991, pp. 203-204). Western yellow-billed cuckoos have evolved larger eggs and thicker eggshells, which would help them cope with potential higher egg water loss in the hotter, dryer conditions (Hamilton and Hamilton 1965, pp. 426-430; Ar et al. 1974, pp. 153-158; Rahn and Ar 1974, pp. 147-152). A study on the South Fork Kern River showed that lower temperatures and higher humidity were found at nest sites when 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).
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. Where groundwater levels are elevated so riparian forest trees can access the water, habitat for nesting, foraging, and migrating western yellow-billed cuckoos can develop and thrive. Goodding's willows (Salix gooddingii) and Fremont cottonwoods (Populus fremontii) do not regenerate if the groundwater levels fall below 6 ft (2 m) (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, pp. 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 flowing rivers and streams, elevated subsurface groundwater tables, and high humidity as essential physical and biological features of western yellow-billed cuckoo habitat.
Conditions for Germination and Regeneration of Riparian Zone Trees The abundance and distribution of fine sediment deposited on floodplains is critical for the development, abundance, distribution, maintenance, and germination of trees in the riparian zone that become western yellow-billed cuckoo habitat. These sediments become seedbeds for germination and growth of the riparian vegetation upon which western yellow-billed cuckoos depend. These sediments must be accompanied by sufficient surface moisture for seed germination and sufficient ground water levels for survival of seedlings and saplings (Stromberg 2001, pp. 27-28). The lack of stream flow processes, which deposit such sediments, may lead riparian forested areas to senesce and to become degraded and not able to support the varied vegetative structure required for western yellow-billed cuckoo nesting and foraging.
Therefore, based on the information above, we identify flowing perennial rivers and streams and deposited fine sediments as essential physical and biological features of western yellow-billed cuckoo habitat.
Cover or Shelter Riparian vegetation also provides the western yellow-billed cuckoo with cover and shelter while foraging and nesting. Placing nests in dense vegetation provides cover and shelter from predators that would search for adult western yellow-billed cuckoos, their eggs, nestlings, and fledged young. Northern harriers (Circus cyaneus) have been observed preying on western yellow-billed cuckoo nestlings at open riparian restoration sites. Dense foliage precludes the entry of northern harriers into the habitat patch (Laymon 1998, pp. 12-14). Likewise, within the breeding range, western yellow-billed cuckoos also use riparian vegetation for cover and shelter as movement corridors between foraging sites and as post-breeding dispersal areas for adults and young. Movement corridors provide a place to rest and provide cover and shelter from predators during movement from one foraging area to another. These movement corridors within the breeding range, even though not used for nesting, are important resources affecting local and regional western yellow-billed cuckoo productivity and survival.
Therefore, based on the information above, we identify riparian trees including willow, cottonwood, alder (Alnus sp.), walnut (Juglans sp.), sycamore (Platanus sp.), boxelder (Acer sp.), ash (Fraxinus sp.), mesquite, and tamarisk that provide cover and shelter for foraging and dispersing western yellow-billed cuckoos as essential physical or biological features of western yellow-billed cuckoo habitat.
Sites for Breeding, Reproduction, or Rearing (or Development) of Offspring The western yellow-billed cuckoo utilizes nesting sites in riparian habitat where conditions are cooler and more humid than in the surrounding environment. 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. Throughout the range, most nests are placed in willows (72 percent of 217 nests), and willows generally dominate nesting sites. Willow species used for nest trees include Goodding's black willow, red willow (Salix laevigata), and coyote willow (Salix exigua) (Laymon 1998, p. 7; Hughes 1999, p. 13).
Nests have also been documented in other riparian trees, 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), box elder (less than 1 percent), and soapberry (Sapindus saponaria) (less than 1 percent). They have also nested in Arizona walnut (Juglans major), alder (Alnus rhombifolia and A. oblongifolia), and Arizona sycamore (Platanus wrightii) (Laymon 1980, p. 8; Laymon 1998, p. 7; Hughes 1999, p. 13; Corman and Magill 2000, p. 16; Launer et al. 2000, p. 22; 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). 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 prefer to build their nests (Laymon 1980, pp. 6-8). These orchard-nesting western yellow-billed cuckoos did not forage in the orchard, but flew across the river to forage in riparian habitat. Tamarisk is also a riparian species that may be associated with breeding under limited conditions; western yellow-billed cuckoo will sometimes build their nests and forage in tamarisk, but there is always a native riparian tree component within the occupied habitat (Gaines and Laymon 1984, p. 72; Johnson et al. 2008a, pp. 203-204). Johnson et al. (2008a, pp. 203-204) conducted Statewide surveys in Arizona of almost all historically occupied habitat of the western yellow-billed cuckoo 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 and only 5 percent within habitats dominated by tamarisk. Even in the tamarisk-dominated habitat, cottonwoods were still present at all but two of these sites.
Nest site characteristics 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. 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 and 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. Canopy cover directly above the nest is generally dense and averages 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 addition to the dense, generally willow-dominated nesting grove, western yellow-billed cuckoos need adequate foraging areas in the vicinity of the nest. Foraging areas can be less dense with lower levels of canopy cover and often have a high proportion of cottonwoods in the canopy. Optimal 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.
As discussed above, the habitat patches used by western yellow-billed cuckoos vary in size and shape with optimal areal extent being over 200 ac (81 ha) in size (see Space for Individual and Population Growth for Normal Behavior). The larger the site, 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). Sites can be relatively dense, contiguous stands or irregularly shaped mosaics of dense vegetation with open areas.
Western yellow-billed cuckoos typically have large home ranges during the breeding season, averaging more than 100 ac (40 ha) per individual, and nest at low densities of less than 1 pair per 100 ac (40 ha) (Laymon et al. 1997, p. 19; Laymon and Williams 2002, p. 5; Halterman 2009, p. 93; Sechrist et al. 2009, p. vii; McNeil et al. 2010, p. 75; McNeil et al. 2011, p. 37; McNeil et al. 2012, p. 69). As a result, a large amount of habitat is required to support even a small population of western yellow-billed cuckoos.
Therefore, based on the information above, we identify blocks of riparian habitat greater than 200 ac (81 ha) in extent and greater than 325 ft (100 m) in width, with one or more densely foliaged, willow-dominated nesting sites and cottonwood-dominated foraging sites, to be a physical or biological feature for the species' habitat.
Habitats Protected From Disturbance or Representative of the Historical, Geographical, and Ecological Distributions of the Species The occupied rivers and streams that are proposed for designation contain physical and biological features that are representative of the historic and geographical distribution of the species.
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