Endangered and Threatened Wildlife and Plants; Designation of Revised Critical Habitat for Southwestern Willow Flycatcher, 50542-50629 [2011-19713]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 76, Number 157 (Monday, August 15, 2011)]
[Proposed Rules]
[Pages 50542-50629]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-19713]



[[Page 50541]]

Vol. 76

Monday,

No. 157

August 15, 2011

Part II





Department of the Interior





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Fish and Wildlife Service





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50 CFR Part 17





Endangered and Threatened Wildlife and Plants; Designation of Revised 
Critical Habitat for Southwestern Willow Flycatcher; Proposed Rule

Federal Register / Vol. 76, No. 157 / Monday, August 15, 2011 / 
Proposed Rules

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2011-0053; MO 92210-0-0009]
RIN 1018-AX43


Endangered and Threatened Wildlife and Plants; Designation of 
Revised Critical Habitat for Southwestern Willow Flycatcher

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
revise critical habitat for the southwestern willow flycatcher 
(Empidonax traillii extimus) (flycatcher) under the Endangered Species 
Act of 1973, as amended (Act). In total, approximately 3,364 km stream 
kilometers (2,090 stream miles) are being proposed for designation as 
critical habitat. These areas are being proposed as stream segments, 
with the lateral extent including the riparian areas and streams that 
occur within the 100-year floodplain or flood-prone areas. The proposed 
critical habitat is located on a combination of Federal, State, Tribal, 
and private lands in Imperial, Inyo, Kern, Los Angeles, Mono, Orange, 
Riverside, Santa Barbara, San Bernardino, San Diego, and Ventura 
Counties in California; Clark, Lincoln, and Nye Counties in southern 
Nevada; Kane, San Juan, and Washington Counties in southern Utah; 
Alamosa, Conejos, Costilla, La Plata, and Rio Grande Counties in 
southern Colorado; Apache, Cochise, Gila, Graham, Greenlee, La Paz, 
Maricopa, Mohave, Pima, Pinal, Santa Cruz, Yavapai, and Yuma Counties 
in Arizona; and Catron, Cibola, Dona Ana, Grant, Hidalgo, McKinley, 
Mora, Rio Arriba, Santa Fe, San Juan, Sierra, Soccoro, Taos, and 
Valencia Counties in New Mexico.

DATES: We will accept comments received or postmarked on or before 
October 14, 2011. We must receive requests for public hearings, in 
writing, at the address shown in the FOR FURTHER INFORMATION CONTACT 
section by September 29, 2011.

ADDRESSES: You may submit comments by one of the following methods:
    (1) Electronically: Go to the Federal eRulemaking Portal: https://www.regulations.gov. In the Enter Keyword or ID box, enter Docket No. 
FWS-R2-ES-2011-0053, which is the docket number for this rulemaking.
    (2) By hard copy: Submit by U.S. mail or hand-delivery to: Public 
Comments Processing, Attn: FWS-R2-ES-2011-053; Division of Policy and 
Directives Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax 
Drive, MS 2042-PDM; Arlington, VA 22203.
    We will not accept e-mail or faxes. We will post all comments on 
https://www.regulations.gov. This generally means that we will post any 
personal information you provide us (see the Public Comments section 
below for more information).

FOR FURTHER INFORMATION CONTACT: Steve Spangle, Field Supervisor, U.S. 
Fish and Wildlife Service, Arizona Ecological Services Office, 2321 
West Royal Palm Rd., Suite 103, Phoenix, AZ 85021; telephone 602-242-
0210; facsimile 602-242-2513. If you use a telecommunications device 
for the deaf (TDD), call the Federal Information Relay Service (FIRS) 
at 800-877-8339.

SUPPLEMENTARY INFORMATION: 

Public Comments

    We intend that any final action resulting from this proposed rule 
will be based on the best scientific and commercial data available and 
be as accurate and as effective as possible. Therefore, we request 
comments or information from other concerned government agencies, the 
scientific community, industry, or any other interested party 
concerning this proposed rule. We particularly seek comments 
concerning:
    (1) The reasons why we should or should not designate habitat as 
``critical habitat'' under section 4 of the Act (16 U.S.C. 1531 et 
seq.), including whether there are threats to the species from human 
activity, the degree of which 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.
    (2) Specific information on:
    (a) The amount and distribution of southwestern willow flycatcher 
habitat;
    (b) What areas that were occupied at the time of listing that 
contain features essential to the conservation of the species should be 
included in the designation and why;
    (c) What areas not occupied at the time of listing that meet our 
criteria for being essential to the conservation of the species should 
be included in the designation and why;
    (d) Special management considerations or protection that may be 
needed for the physical or biological features essential to the 
conservation of the species in the critical habitat areas we are 
proposing, including managing for the potential effects of climate 
change;
    (e) Stream segments, many of which are highlighted in the 
Southwestern Willow Flycatcher Recovery Plan (Recovery Plan) (Service 
2002) and included in this proposed rule, that are not now known to 
have flycatcher nesting territories or known to only have few nesting 
flycatchers that may be capable of being improved for flycatcher 
recovery purposes. We specifically seek information about streams 
within the Amargosa, Salton, Mohave, Powell, San Juan, Santa Cruz, and 
Hassayampa and Agua Fria Management Units. Please provide information 
on flycatcher distribution and abundance, habitat quality, habitat 
locations, habitat improvement projects, management actions needed to 
improve habitat, habitat quality limitations, habitat recovery 
potential, and any other flycatcher or flycatcher-habitat-specific 
information, and;
    (f) Flycatcher habitat suitability in specific areas within the 
Santa Ana and San Diego Management Units in southern California. Please 
provide information on flycatcher habitat suitability for recovery at 
the following areas: (1) Entirety of Temescal Wash including Alberhill 
Creek in Riverside County; (2) entirety of Murrieta Creek in Riverside 
County; (3) Potrero Creek near the city of Beaumont in Riverside 
County; (4) Cajon Creek from Lone Pine Canyon to California State 
Highway 138 in San Bernardino County; and (5) Tijuana River from Dairy 
Mart Road to the Tijuana River Estuary in San Diego County.
    (3) Land use designations and current or planned activities in the 
subject areas and their possible impacts on proposed critical habitat.
    (4) Information on the projected and reasonably likely impacts of 
climate change on the flycatcher, the features essential to its 
conservation and the areas proposed as critical habitat.
    (5) Any probable economic, national security, environmental, 
cultural, or other relevant impacts of designating any area that may be 
included in the final designation; in particular, any impacts on small 
entities, and the benefits of including or excluding areas that exhibit 
these impacts.
    (6) 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 
any specific area outweigh the benefits of including that area under 
section 4(b)(2) of the Act, in particular.

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    (a) 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, which describe the commitment and 
assurances of protection of the physical or biological features of 
flycatcher critical habitat; property boundaries; flycatcher status, 
distribution, and abundance; and management actions to protect the 
physical or biological features of flycatcher habitat.
    (b) For lands we evaluated and excluded from critical habitat under 
section 4(b)(2) of the Act during the 2005 flycatcher critical habitat 
designation and those who wish to seek exclusion for this re-
designation, please resubmit your request. In addition to your request, 
please include any updated information that pertains to the commitment 
and assurances of protection of flycatcher habitat; the physical or 
biological features of flycatcher critical habitat; property 
boundaries; flycatcher status, distribution, and abundance; and 
management actions to protect the physical or biological features of 
flycatcher habitat. Include the specific results of implementing these 
management plans since our 2005 flycatcher critical habitat 
designation.
    (c) Information concerning the benefits of excluding or retaining 
lands we identify in this proposed critical habitat rule under 
consideration for exclusion under section 4(b)(2) of the Act. We 
specifically seek information about the possible exclusion of Elephant 
Butte Reservoir; areas within the operating pool of the reservoir may 
be subject to exclusion under 4(b)(2) of the Act if we determine that 
the benefits of excluding the area due to potential impacts to water 
operations outweigh the benefits to the subspecies of including the 
area as critical habitat.
    (7) 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.
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in the ADDRESSES section. We will not 
accept comments sent by e-mail or fax or to an address not listed in 
the ADDRESSES section. We will post your entire comment--including your 
personal identifying information--on https://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 e-mail 
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 https://www.regulations.gov, or by 
appointment, during normal business hours, at the U.S. Fish and 
Wildlife Service, Arizona Ecological Services Office in Phoenix, 
Arizona (see FOR FURTHER INFORMATION CONTACT).

Background

    It is our intent to include only those topics directly relevant to 
the designation of critical habitat for the southwestern willow 
flycatcher (flycatcher) in this proposed rule. Background information 
on the flycatcher can be found in the final flycatcher critical habitat 
rule published in the Federal Register on October 19, 2005 (70 FR 
60886); our October 12, 2004, proposed critical habitat rule (69 FR 
60706); the Southwestern Willow Flycatcher Recovery Plan (Recovery 
Plan) (Service 2002); our first flycatcher critical habitat 
designation, published July 22, 1997 (62 FR 39129), and August 20, 1997 
(62 FR 44228); the final flycatcher listing rule (60 FR 10694; February 
27, 1995); the 10-year flycatcher study in central Arizona (Paxton et 
al. 2007a); the 2007 rangewide status report (Durst et al. 2008); and 
flycatcher survey protocol and natural history summary (Sogge et al. 
2010). Other reports can be retrieved from the U.S. Geological Survey's 
(USGS) flycatcher site at https://sbsc.wr.usgs.gov/cprs/research/projects/swwf. The current 2005 critical habitat rule remains in effect 
while this rulemaking process proceeds.
    The flycatcher is a small, insect-eating, neotropical migrant bird, 
from the taxonomic order Passeriformes. It grows to about 15 
centimeters (5.8 inches) in length. The flycatcher is one of four 
subspecies of the willow flycatcher currently recognized (Hubbard 1987, 
pp. 3-6; Unitt 1987, pp. 137-144), although Browning (1993, p. 248) 
suggests a possible fifth subspecies (Empidonax traillii campestris) in 
the central and midwestern United States. As an insect-eating 
generalist (Service 2002, p. 26), the flycatcher eats a wide range of 
invertebrate prey including flying, and ground- and vegetation-
dwelling, insect species of terrestrial and aquatic origins (Drost et 
al. 2003, pp. 96-102). The flycatcher spends the winter in locations 
such as southern Mexico, Central America, and probably South America 
(Ridgely and Gwynne 1989, p. 303; Stiles and Skutch 1989, pp. 321-322; 
Howell and Webb 1995, pp. 496-497; Unitt 1997, pp. 70-73; Koronkiewicz 
et al. 1998, p. 12; Unitt 1999, p. 14).
    All willow flycatcher subspecies spend time migrating and breeding 
in the United States from April to September. Use of riparian habitats 
along major drainages in the Southwest during migration has been 
documented (Sogge et al. 1997, pp. 3-4; Yong and Finch 1997, p. 253; 
Johnson and O'Brien 1998, p. 2; McKernan and Braden 1999, p. 17; 
Koronkiewicz et al. 2004, pp. 9-11). Many of the willow flycatchers 
found migrating are detected in riparian habitats or patches (small 
areas of riparian vegetation) that would be unsuitable for nest 
placement (the vegetation structure is too short or sparse, or the 
patch of vegetation is too small). In these drainages migrating 
flycatchers may use a variety of riparian habitats, including ones 
dominated by native or exotic plant species, or mixtures of both 
(Service 2002, p. E-3). Willow flycatchers, like most small, migratory, 
insect-eating birds, require food-rich stopover areas in order to 
replenish energy reserves and continue their northward or southward 
migration (Finch et al. 2000, pp. 71, 78, and 79; Service 2002, pp. E-3 
and 42). Migration stopover areas are likely critically important for 
flycatcher productivity and survival (Sogge et al. 1997, p. 13; Yong 
and Finch 1997, p. 253; Service 2002, pp. E-3,19).
    The historical breeding range of the flycatcher includes southern 
California, southern Nevada, southern Utah, Arizona, New Mexico, 
western Texas, southwestern Colorado, and extreme northwestern Mexico. 
The flycatcher's current range is similar to the historical range, but 
the quantity of suitable habitat within that range is reduced from 
historical levels (Service 2002, pp. 7-10).
    The known geographical area historically occupied by this 
flycatcher subspecies was once larger (Service 2002, pp. 7-10). 
Historical records described nesting birds in southern California, 
Nevada, Utah; Arizona and New Mexico; western Texas; southwestern 
Colorado; and extreme northwestern Mexico (Hubbard 1987, pp. 6-10; 
Unitt 1987, pp. 144-152; Browning 1993, pp. 248, 250). At the time of 
listing in February 1995 (60 FR 10694), the distribution and abundance 
of nesting flycatchers, their natural history, and areas occupied by 
nonbreeding, migrating, and dispersing flycatchers were not well known. 
In February 1995, 359 territories were

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known only from California, Arizona, and New Mexico. Unitt (1987, p. 
156) estimated the entire population was, ``well under 1,000 pairs, 
more likely 500,'' and 230 to 500 territories were estimated to exist 
in the July 23, 1993, flycatcher listing proposal (58 FR 39495, p. 
39498).
    At the time of listing, breeding sites in California, Nevada, Utah, 
and Colorado described by Unitt (1987, pp. 149-152) were adopted as the 
subspecies' northern boundary. However, the collection and analysis of 
genetic material across this part of the bird's range has since refined 
this boundary (Paxton 2000, pp. 3, 18-20), and reduced the extent of 
the northern boundary of this southwestern subspecies in Utah and 
Colorado (Service 2002, Figure 3). Territories once believed to be held 
by southwestern willow flycatchers in Utah and Colorado are now more 
accurately known to be occupied by a different, non-listed willow 
flycatcher subspecies. As a result, the southwestern subspecies' range 
only occurs in the southernmost portions of Utah and Colorado. This 
genetic work also confirmed the identity of southwestern willow 
flycatcher subspecies throughout the rest of its range.
    The USGS has continued to collect genetic information to help 
refine the northern boundary of the subspecies' range in Utah, 
Colorado, and New Mexico (Paxton et al. 2007b). They reconfirmed the 
genetic markers that identify differences among flycatcher subspecies, 
with breeding sites clustering into two groups separated approximately 
along the currently recognized boundary; however, they noted a distinct 
genetic boundary line between the subspecies does not exist (Paxton et 
al. 2007b, p. 17). Instead of a distinct boundary, they suggested that 
the boundary should be thought of as a ``region of genetic overlap'' 
(Paxton et al. 2007b, p. 17). They also described that this genetic 
overlap region will likely widen and contract over time based upon 
habitat changes (Paxton et al. 2007b, p. 17). An additional 
complication in refining the subspecies' northern boundary is that this 
region is sparsely populated with breeding flycatchers, and therefore 
only minimal information is available that would help narrow down the 
location of a boundary (Paxton et al. 2007b, p. 16). We continue to 
seek out territories and collect genetic samples to further our 
understanding of this area, but we currently recognize the northern 
geographic boundary of the flycatcher as described in the Recovery Plan 
(Service 2002, Figures 3, 4).
    The flycatcher currently breeds in areas from near sea level to 
over 2,600 meters (m) (8,500 feet [ft]) (Durst et al. 2008, p. 14) in 
vegetation alongside rivers, streams, or other wetlands (riparian 
habitat). It establishes nesting territories, builds nests, and forages 
where mosaics of relatively dense and expansive growths of trees and 
shrubs are established, near or adjacent to surface water or underlain 
by saturated soil (Sogge et al. 2010, p. 4). Habitat characteristics 
such as dominant plant species, size and shape of habitat patch, tree 
canopy structure, vegetation height, and vegetation density vary widely 
among breeding sites. Nests are typically placed in trees where the 
plant growth is most dense, where trees and shrubs have vegetation near 
ground level, and where there is a low-density canopy. Some of the more 
common tree and shrub species currently known to comprise nesting 
habitat include Goodings willow (Salix gooddingii), coyote willow 
(Salix exigua), Geyers willow (Salix geyerana), arroyo willow (Salix 
lasiolepis), red willow (Salix laevigata), yewleaf willow (Salix 
taxifolia), boxelder (Acer negundo), tamarisk (also known as saltcedar, 
Tamarix ramosissima), and Russian olive (Eleagnus angustifolia) 
(Service 2002, p. D-2). While there are exceptions, generally 
flycatchers are not found nesting in areas without willows, tamarisk, 
or both.
    A breeding site is simply an area along the river that has been 
described while surveying for flycatcher territories (Service 2002, p. 
C-4; Sogge et al. 2010, p. 34). A breeding site can contain none, only 
one, or many territories. However, within this proposed rule, we refer 
to breeding sites as areas where flycatcher territories were detected. 
A territory is defined as a discrete area defended by a resident single 
flycatcher or pair of flycatchers within a single breeding season 
(Sogge et al. 2010, p. 34). This is usually evidenced by the presence 
of a singing male, and possibly one or more mates (Sogge et al. 2010, 
p. 34).
    At the end of 2007, 1,299 flycatcher breeding territories were 
estimated to occur throughout southern California, southern Nevada, 
southern Utah, southern Colorado, Arizona, and New Mexico (Durst et al. 
2008, p. 4). Some of the flycatcher breeding sites having the highest 
number of territories are found along the middle Rio Grande and upper 
Gila River in New Mexico, and Roosevelt Lake and the San Pedro and Gila 
River confluence area in central Arizona.
    Flycatchers are believed to exist and interact as groups of 
metapopulations (Service 2002, p. 72). A metapopulation is a group of 
geographically separate flycatcher breeding populations connected to 
each other by immigration and emigration (Service 2002, p. 72). 
Flycatcher populations are most stable where many connected sites or 
large populations exist (Service 2002, p. 72). Metapopulation 
persistence or stability is more likely to improve by adding more 
breeding sites than with the addition of territories to existing sites 
(Service 2002, p. 72). This would distribute birds across a greater 
geographical range, minimize risk of simultaneous catastrophic 
population loss, and avoid genetic isolation (Service 2002, p. 72).
    Flycatchers have higher site fidelity (to a local area) than nest 
fidelity (to a specific nest location) and can move among sites within 
stream drainages and between drainages (Kenwood and Paxton 2001, pp. 
29-31). Within-drainage movements are more common than between-drainage 
movements (Kenwood and Paxton 2001, p. 18). Juvenile flycatchers were 
the group of flycatchers that moved (dispersed) the farthest to new and 
distant breeding sites from the area where they hatched (Paxton et al. 
2007a, p. 74). The USGS's 10-year flycatcher study in central Arizona 
(Paxton et al. 2007a) is the key movement study that has generated 
these conclusions, augmented by other flycatcher banding and re-
sighting studies (Sedgwick 2004, p. 1103; McLeod et al. 2008, p. 110).
    The difference in flycatcher dispersal distance among different 
study areas and regions reflects the varying spatial arrangement of 
breeding habitat, illustrating how dispersal tendencies are influenced 
by the geographic distribution of habitat at the stream segment, 
drainage, and landscape scales (Paxton et al. 2007a, p. 75). While 
USGS' study focused its effort in central Arizona at two of the largest 
breeding sites, it also included multiple auxiliary sites (up to 444 km 
or 275 mi away), along with other researchers and surveyors across the 
flycatcher's range paying attention to whether flycatchers were banded 
or not. As a result, the broad scope of the study of flycatcher 
movement extends broadly beyond a localized, regional area, where 
habitat configuration dominates the results.
    Banded flycatchers from season-to-season (and sometimes within 
season) were recorded moving from 50 m (150 feet) to 444 km (275 mi) to 
try and nest. Some long-distance season-to-season movement records 
captured flycatchers moving from the Basin and Mohave Recovery Unit to 
the Lower Colorado Recovery Unit and from the Lower

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Colorado Recovery Unit to the Gila Recovery Unit.
    The USGS assimilated all of the flycatcher movement information and 
concluded that rapid colonization and increased metapopulation 
stability could be accomplished by establishing breeding sites within 
30 to 40 km (18 to 25 mi) of each other (Paxton et al. 2007a, p. 4). 
Flycatchers at breeding sites configured in this way would be able to 
regularly disperse to new breeding sites or move between known breeding 
sites within the same year or from year-to-year. This proximity of 
sites would increase the connectivity and stability of the 
metapopulation and smaller, more distant breeding sites.
    Because the breeding range of the flycatcher encompasses a broad 
geographic area with much site variation, management of recovery is 
approached in the Recovery Plan by dividing the flycatcher's range into 
6 Recovery Units, each of which are further subdivided into 4 to 7 
Management Units (for a total of 32 Management Units) (Service, pp. 61-
63). This provides an organizational strategy to ``characterize 
flycatcher populations, structure recovery goals, and facilitate 
effective recovery actions that should closely parallel the physical, 
biological, and logistical realities on the ground'' (Service 2002, p. 
61). Recovery goals are recommended for 29 of the 32 Management Units 
(see Methodology Overview section). Recovery Units are defined based on 
large watershed and hydrologic units. Within each Recovery Unit, 
Management Units are based on watershed or major drainage boundaries at 
the Hydrologic Unit Code Cataloging Unit level (standard watershed 
boundaries which have already been defined for other purposes). The 
``outer'' boundaries of some Recovery Units and Management Units were 
defined by the flycatcher's range boundaries. This proposed designation 
of critical habitat is organized geographically within these Recovery 
Units and Management Units (see ``Methodology Overview'' section 
below).
    The Recovery Plan (Service 2002) provides reasonable actions 
recommended to recover the flycatcher and provides two criteria, either 
of which can be met, in order to consider downlisting the species to 
threatened (Service 2002, pp. 77-78). The first alternative for 
downlisting requires reaching a total population of 1,500 flycatcher 
territories geographically distributed among all Recovery Units and 
maintained for 3 years with habitat protections (Service 2002, pp. 77-
78). Habitat protections include a variety of options such as HCPs, 
conservation easements, or safe harbor agreements. The second 
alternative approach for downlisting calls for reaching a population of 
1,950 territories also strategically distributed among all Recovery and 
Management Units for 5 years without additional habitat protection 
(Service 2002, pp. 77-78).
    In order to delist this flycatcher subspecies (to remove it from 
the List of Endangered and Threatened Wildlife and Plants), the 
Recovery Plan recommends that a minimum of 1,950 territories are 
geographically distributed among all Recovery and Management Units, and 
that twice the amount of habitat is provided to maintain these 
territories over time. Second, these habitats must be protected from 
threats to assure maintenance of these populations and habitat for the 
foreseeable future through development and implementation of 
conservation management agreements (Service 2002, pp. 79-80). Third, 
all of these delisting criteria must be accomplished and their 
effectiveness demonstrated for a period of 5 years (Service 2002, pp. 
79-80). This critical habitat proposal is structured to allow the 
Service to work toward achieving the numerical, geographical, and 
habitat-related recovery goals.
    Twice the amount of suitable habitat is needed to support the 
numerical territory goals, because the long-term persistence of 
flycatcher populations cannot be assured by protecting only those 
habitats in which flycatchers currently breed (Service 2002, p. 80). It 
is important to recognize that most flycatcher breeding habitats are 
susceptible to future changes in site hydrology (natural or human-
related), human impacts such as development or fire, and natural 
catastrophic events such as flood or drought (Service 2002, p. 80). 
Furthermore, as the vegetation at sites matures, it can lose the 
structural characteristics that make it suitable for breeding 
flycatchers (Service 2002, p. 80). These and other factors can destroy 
or degrade breeding sites, such that one cannot expect any given 
breeding site to remain suitable in perpetuity (Service 2002, p. 80). 
Thus, it is necessary to have additional suitable habitat available to 
which flycatchers, displaced by such habitat loss or change, can 
readily move (Service 2002, p. 80).

Previous Federal Actions

    The flycatcher was listed as endangered on February 27, 1995 (60 FR 
10694). On July 22, 1997, we published a final critical habitat 
designation for the flycatcher along 964 river km (599 river mi) in 
Arizona, California, and New Mexico (62 FR 39129). We published a 
correction notice on August 20, 1997, on the lateral extent of critical 
habitat (62 FR 44228).
    As a result of a 1998 lawsuit from the New Mexico Cattlegrower's 
Association, on October 19, 2005 (70 FR 60886), we published a revised 
final flycatcher critical habitat rule for portions of Arizona, 
California, New Mexico, Nevada, and Utah, totaling approximately 48,896 
ha (120,824 ac) or 1,186 km (737 mi). River segments were designated as 
critical habitat in 15 of the 32 Management Units described in the 
Recovery Plan (Service 2002, p. 63).
    We were sued by the Center for Biological Diversity over our 2005 
critical habitat rule, and on July 13, 2010, we agreed to redesignate 
critical habitat. The resulting settlement left the existing critical 
habitat designation from 2005 in effect, and required that we deliver a 
proposed rule for new revised critical habitat to the Federal Register 
by July 31, 2011, and a final rule by July 31, 2012.

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 that are necessary to bring 
an endangered or threatened species to the point at which the measures 
provided under 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

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requirement that Federal agencies ensure, in consultation with the 
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 to access 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) would apply, but even 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.
    For inclusion in a critical habitat designation, the habitat within 
the geographical area occupied by the species at the time it was listed 
must contain physical or biological features which are essential to the 
conservation of the species and which may require special management 
considerations or protection. Critical habitat designations identify, 
to the extent known using the best scientific and commercial data 
available, those physical or biological features that are essential to 
the conservation of the species (such as space, food, cover, and 
protected habitat), focusing on the principal biological or physical 
constituent elements (primary constituent elements) within an area that 
are essential to the conservation of the species (such as roost sites, 
nesting grounds, seasonal wetlands, water quality, tide, soil type). 
Primary constituent elements are the elements of physical or biological 
features that, when laid out in the appropriate quantity and spatial 
arrangement to provide for a species' life-history processes, are 
essential to the conservation of the species.
    Under the Act, 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. We designate critical habitat in areas outside the 
geographical area occupied by a species only when a designation limited 
to its range would be inadequate to ensure the conservation of the 
species. When the best available scientific data do not demonstrate 
that the conservation needs of the species require such additional 
areas, we will not designate critical habitat in areas outside the 
geographical area occupied by the species. An area currently occupied 
by the species but that was not occupied at the time of listing may, 
however, be essential to the conservation of the species and may be 
included in the critical habitat designation.
    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.
    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 these 
reasons, a critical habitat designation does not signal that habitat 
outside the designated area is unimportant or may not be required 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 insure their actions are not likely to 
jeopardize the continued existence of any endangered or threatened 
species, and (3) the prohibitions of section 9 of the Act if actions 
occurring in these areas may affect the species. 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, 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 sections 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 (in this case a subspecies) 
at the time of listing to designate as critical habitat, we consider 
the physical or biological features essential to the conservation of 
the flycatcher and which may 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 flycatcher from studies of this subspecies' habitat, ecology, and 
life history as described below. The most comprehensive, current, and 
thorough documents are the Recovery Plan (Service 2002, Appendix D), 
Survey Protocol and Natural History Summary (Sogge et al. 2010), and 
10-year central Arizona ecology study (Paxton et al. 2007a).
    In general, the areas proposed for designation as critical habitat 
are designed to provide sufficient riparian habitat for breeding, non-
breeding, territorial, dispersing, and migrating flycatchers in order 
to reach the

[[Page 50547]]

geographic distribution, abundance, and habitat-related recovery goals 
described in the Recovery Plan (Service 2002, pp. 77-85). We are not 
proposing any areas as critical habitat solely because they serve as a 
migration habitat. Instead, the areas we are proposing serve a variety 
of functions, including habitat to be used by migrating flycatchers. 
The habitat components important for conservation of this subspecies 
were determined from studies of flycatcher behavior and habitat use 
throughout the bird's range (see Background section).
    In general, the physical or biological features of critical habitat 
for nesting flycatchers are found in the riparian areas within the 100-
year floodplain or flood-prone area. Flycatchers use riparian habitat 
for feeding, sheltering, and cover while breeding, migrating, and 
dispersing. It is important to recognize that flycatcher habitat is 
ephemeral in its presence, and its distribution is dynamic in nature 
because riparian vegetation is prone to periodic disturbance (such as 
flooding) (Service 2002, p. 17). Even with the dynamic shifts in 
habitat conditions, one or more of the primary constituent elements 
described below are found throughout each of the units that we are 
proposing as critical habitat.
    Flycatcher habitat may become unsuitable for breeding through 
maturation or disturbance of the riparian vegetation, but it may remain 
suitable for use during migration or for foraging. This situation may 
be only temporary, and vegetation may cycle back into suitability as 
breeding habitat (Service 2002, p. 17). Therefore, it is not practical 
to assume that any given breeding habitat area will remain suitable 
over the long term or persist in the same location (Service 2002, p. 
17). Over a 5-year period, flycatcher habitat can, in optimum 
conditions, germinate, be used for migration or foraging, continue to 
grow, and eventually be used for nesting. Thus, flycatcher habitat that 
is not currently suitable for nesting at a specific time, but is useful 
for foraging and migration, can still be important for flycatcher 
conservation. Feeding sites and migration stopover areas are important 
components for the flycatcher's survival, productivity, and health, and 
they can also be areas where new breeding habitat develops as nesting 
sites are lost or degraded (Service 2002, p. 42). These successional 
cycles of habitat change are important for long-term persistence of 
flycatcher habitat.
    Based on our current knowledge of the life history and ecology of 
the flycatcher and the relationship of its life-history functions to 
its habitat, as summarized in the ``Background'' section above and in 
more detail in the Recovery Plan (Service 2002, Chapter II), it is 
important to recognize the interconnected nature of the physical or 
biological features that provide the primary constituent elements of 
critical habitat. Specifically, we consider the relationships between 
river function, hydrology, floodplains, aquifers, and plant growth, 
which form the environment essential to the conservation of the 
flycatcher.
    The hydrologic regime (stream flow pattern) and supply of (and 
interaction between) surface and subsurface water is a driving factor 
in the long-term maintenance, growth, recycling, and regeneration of 
flycatcher habitat (Service 2002, p. 16). As streams reach the 
lowlands, their gradients typically flatten and surrounding terrain 
opens into broader floodplains (Service 2002, p. 32). In these 
geographic settings, the stream-flow patterns (frequency, magnitude, 
duration, and timing) will provide the necessary stream-channel 
conditions (wide configuration, high sediment deposition, periodic 
inundation, recharged aquifers, lateral channel movement, and elevated 
groundwater tables throughout the floodplain) that result in the 
development of flycatcher habitat (Poff et al. 1997, pp. 770-772; 
Service 2002, p. 16). Allowing the river to flow over the width of the 
floodplain, when overbank flooding occurs, is integral to allow 
deposition of fine moist soils, water, nutrients, and seeds that 
provide the essential material for plant germination and growth. An 
abundance and distribution of fine sediments extending farther 
laterally across the floodplain and deeper underneath the surface 
retains much more subsurface water, which in turn supplies water for 
the development of the vegetation that provides flycatcher habitat and 
micro-habitat conditions (Service 2002, p. 16). The interconnected 
interaction between groundwater and surface water contributes to the 
quality of riparian vegetation community (structure and plant species) 
and will influence the germination, density, vigor, composition, and 
the ability of vegetation to regenerate and maintain itself (Arizona 
Department of Water Resources 1994, pp. 31-32).
    In many instances, flycatcher breeding sites occur along streams 
where human impacts are minimized enough to allow more natural 
processes to create, recycle, and maintain flycatcher habitat. However, 
there are also breeding sites that are supported by various types of 
supplemental water including agricultural and urban run-off, treated 
water outflow, irrigation or diversion ditches, reservoirs, and dam 
outflows (Service 2002, p. D-15). Although the waters provided to these 
habitats might be considered ``artificial,'' they are often important 
for maintaining the habitat in appropriate condition for breeding 
flycatchers within the existing environment.
    In considering the specific physical or biological features 
essential for the conservation of the flycatcher, it is also important 
to consider longer-term processes that may influence habitat changes 
over time, such as climate change. Climate change is a long-term shift 
in the statistics of the weather (including its averages). In its 
Fourth Assessment Report, the Intergovernmental Panel on Climate Change 
(IPCC) defines climate change as, ``a change in the state of the 
climate that can be identified by changes in the mean and/or 
variability of its properties and that persists for an extended period, 
typically decades or longer'' (Solomon et al. 2007, p. 943). Changes in 
climate already are occurring. Examples of observed changes in the 
physical environment include an increase in global average sea level 
and declines in mountain glaciers and average snow cover in both the 
northern and southern hemispheres (IPCC 2007a, p. 30). At continental, 
regional and ocean basin scales, observed changes in long-term trends 
of other aspects of climate include: A substantial increase in 
precipitation in eastern parts of North American and South America, 
northern Europe, and northern and central Asia; declines in 
precipitation in the Mediterranean, southern Africa, and parts of 
southern Asia; and an increase in intense tropical cyclone activity in 
the North Atlantic since about 1970 (IPCC 2007a, p. 30).
    Projections of climate change globally and for broad regions 
through the 21st century are based on the results of modeling efforts 
using state-of-the-art Atmosphere-Ocean General Circulation Models and 
various greenhouse gas emissions scenarios (Meehl et al. 2007, p. 753; 
Randall et al. 2007, pp. 596-599). As is the case with all models, 
there is uncertainty associated with projections due to assumptions 
used and other features of the models. However, despite differences in 
assumptions and other parameters used in climate change models, the 
overall surface air temperature trajectory is one of increased warming 
in comparison to current conditions (Meehl et al. 2007, p. 762; Prinn 
et al. 2011, p. 527). Among the IPCC's projections for the 21st century 
are the following: (1) It is virtually certain there will be warmer

[[Page 50548]]

and more frequent hot days and nights over most of the earth's land 
areas; (2) it is very likely there will be increased frequency of warm 
spells and heat waves over most land areas, and the frequency of heavy 
precipitation events will increase over most areas; and (3) it is 
likely that increases will occur in the incidence of extreme high sea 
level (excludes tsunamis), intense tropical cyclone activity, and the 
area affected by droughts in various regions of the world (IPCC 2007b, 
p. 8).
    Changes in climate can have a variety of direct and indirect 
ecological impacts on species, and can exacerbate the effects of other 
threats. Climate-associated environmental changes to the landscape, 
such as decreased stream flows, increased water temperatures, reduced 
snowpack, and increased fire frequency, affect species and their 
habitats. The vulnerability of a species to climate change impacts is a 
function of the species' sensitivity to those changes, its exposure to 
those changes, and its capacity to adapt to those changes. The best 
available science is used to evaluate the species' response to these 
stressors. We recognize that future climate change may present a 
particular challenge evaluating habitat conditions for species like the 
flycatcher because the additional stressors may push species beyond 
their ability to survive in their present location.
    Exactly how climate change will affect precipitation in the 
specific areas with flycatcher habitat is uncertain. However, 
consistent with recent observations of regional effects of climate 
change, the projections presented for the Southwest predict warmer, 
drier, and more drought-like conditions (Hoerling and Eischeid 2007, p. 
19; Seager et al. 2007, p. 1181). For example, climate simulations of 
the Palmer Drought Severity Index (PSDI) (a calculation of the 
cumulative effects of precipitation and temperature on surface moisture 
balance) for the Southwest for the periods of 2006 to 2030 and 2035 to 
2060 show an increase in drought severity with surface warming. 
Additionally, drought still increases even during wetter simulations 
because of the effect of heat-related moisture loss through evaporation 
and evapotranspiration (Hoerling and Eischeid 2007, p. 19). Annual mean 
precipitation is likely to decrease in the Southwest, as is the length 
of snow season and snow depth (IPCC 2007b, p. 887). Most models project 
a widespread decrease in snow depth in the Rocky Mountains and earlier 
snowmelt (IPCC 2007b, p. 891). In summary, we expect that climate 
change will result in a warmer, drier climate, and reduced surface 
water across the flycatcher's range.
    In the recent past, drought has had both negative and positive 
effects on breeding flycatchers and their habitat, which can provide 
insight into how climate change may affect flycatchers and flycatcher 
habitat. For example, the extreme drought of 2002 caused near complete 
reproductive failure of the 146 flycatcher territories at Roosevelt 
Lake in central Arizona (Smith et al. 2003, pp. 8, 10), and caused a 
dramatic rise in the prevalence of non-breeding and unpaired 
flycatchers (Paxton et al. 2007a, p. 4). While extreme drought during a 
single year can generate impacts to breeding success, drought can also 
have localized short-term benefits in some regulated environments. For 
instance, at some reservoirs (such as Roosevelt Lake, Arizona, and Lake 
Isabella, California), drought led to reduced water storage, which 
increased the exposure of wet soils at the lake's perimeter. Continued 
drought in those areas allowed the exposed areas to grow vegetation and 
become new flycatcher nesting habitat (Ellis et al. 2008, p. 44). These 
short-term and localized habitat increases are not likely sustainable 
with persistent drought or long-term predictions of a drier 
environment, because of the overall importance of the presence of 
surface water and elevated groundwater needed to grow dense riparian 
forests for flycatcher habitat. As a result, we expect long-term 
climate trends associated with a drier climate to have an overall 
negative effect on the available rangewide habitat for flycatchers.
    Considering these issues and other information regarding the 
biology and ecology of the species, we have determined that the 
flycatcher requires the essential physical or biological features 
described below.

Space for Individual and Population Growth and for Normal Behavior

    Streams of lower gradient and more open valleys with a wide and 
broad floodplain are the geological settings that are known to support 
flycatcher breeding habitat from near sea level to about 2,600 m (8,500 
ft) in elevation in southern California, southern Nevada, southern 
Utah, southern Colorado, Arizona, and New Mexico (Service 2002, p. 7). 
Lands with moist conditions that support riparian plant communities are 
areas that provide flycatcher habitat. Conditions like these typically 
develop in lower elevation floodplains as well as where streams enter 
impoundments, either natural (such as beaver ponds) or human-made 
(reservoirs). Low-gradient stream conditions may also occur at high 
elevations, as in the marshy mountain meadows supporting flycatchers in 
the headwaters of the Little Colorado River near Greer, Arizona, or the 
flat-gradient portions of the upper Rio Grande in south-central 
Colorado and northern New Mexico (Service 2002, p. 32). Sometimes, the 
low-gradient wider floodplain exists only at the habitat patch itself 
within a stream that is otherwise steeper in gradient (Service 2002, p. 
D-12).
    Relatively steep, confined streams can also support flycatcher 
breeding habitat (Service 2002, p. D-13). For instance, a portion of 
the San Luis Rey River in California supports a substantial flycatcher 
population and stands out among flycatcher habitats as having a 
relatively high gradient and being confined in a fairly narrow, steep-
sided valley (Service 2002, p. D-13). Even a steep, confined canyon or 
mountain stream may present local conditions where just a small area 
less than a hectare (acre) in size of flycatcher breeding habitat may 
develop (Service 2002, p. D-13). Such sites are important individually 
and in aggregate to contribute to metapopulation stability, site 
connectivity, and gene flow (Service 2002, p. D-13). Flycatchers can 
occupy very small, isolated habitat patches and may occur in fairly 
high densities within those small patches.
    Many willow flycatchers are found along streams using riparian 
habitat during migration (Yong and Finch 1997, p. 253; Service 2002, p. 
E-3). Migration stopover areas can be similar to breeding habitat or 
riparian habitats with less vegetation density and abundance compared 
to areas for nest placement (the vegetation structure is too short or 
sparse or the patch is too small) (Service 2002, p. E-3). For example, 
many locations where migrant flycatchers were detected on the lower 
Colorado River (Koronkiewicz et al. 2004, pp. 9-11) and throughout 
Arizona in 2004 (Munzer et al. 2005, Appendix C) were areas surveyed 
for nesting birds, but no breeding was detected. Such migration 
stopover areas, even though not used for breeding, are critically 
important resources affecting productivity and survival (Service 2002, 
p. E-3). The variety of riparian habitat occupied by migrant 
flycatchers ranges from small patches with shorter and sparser 
vegetation to larger more complex breeding habitats.
    Therefore, based on the information above, we identify streams of 
lower gradient and more open valleys with a wide or broad floodplain an 
essential physical or biological feature of flycatcher habitat. In some 
instances,

[[Page 50549]]

streams in relatively steep, confined area can also support flycatcher 
breeding habitat (Service 2002, p. D-13). These areas support the 
abundance of riparian vegetation used for flycatcher nesting, foraging, 
dispersal, and migration.

Food, Water, Air, Light, Minerals, or Other Nutritional or 
Physiological Requirements

Food
    The flycatcher is somewhat of an insect generalist (Service 2002, 
p. 26), taking a wide range of invertebrate prey including flying, and 
ground- and vegetation-dwelling species of terrestrial and aquatic 
origins (Drost et al. 2003, pp. 96-102). Wasps and bees (Hymenoptera) 
are common food items, as are flies (Diptera), beetles (Coleoptera), 
butterflies, moths and caterpillars (Lepidoptera), and spittlebugs 
(Homoptera) (Beal 1912, pp. 60-63; McCabe 1991, pp. 119-120). Plant 
foods such as small fruits have also been reported (Beal 1912, pp. 60-
63; Roberts 1932, p. 20; Imhof 1962, p. 268), but are not a significant 
food during the breeding season (McCabe 1991, pp. 119-120). Diet 
studies of adult flycatchers (Drost et al. 1998, p. 1; DeLay et al. 
1999, p. 216) found a wide range of prey taken. Major prey items were 
small (flying ants) (Hymenoptera) to large (dragonflies) (Odonata) 
flying insects, with Diptera and Hemiptera (true bugs) comprising half 
of the prey items. Willow flycatchers also took non-flying species, 
particularly Lepidoptera larvae. From an analysis of the flycatcher 
diet along the South Fork of the Kern River, California (Drost et al. 
2003, p. 98), flycatchers consumed a variety of prey from 12 different 
insect groups. Flycatchers have been identified targeting seasonal 
hatchings of aquatic insects along the Salt River arm of Roosevelt 
Lake, Arizona (Paxton et al. 2007a, p. 75).
    Flycatcher food availability may be largely influenced by the 
density and species of vegetation, proximity to and presence of water, 
saturated soil levels, and microclimate features such as temperature 
and humidity (Service 2002, pp. 18, D-12). Flycatchers forage within 
and above the tree canopy, along the patch edge, in openings within the 
territory, over water, and from tall trees as well as herbaceous ground 
cover (Bent 1960, pp. 209-210; McCabe 1991, p. 124). Flycatchers employ 
a ``sit and wait'' foraging tactic, with foraging bouts interspersed 
with longer periods of perching (Prescott and Middleton 1988, p. 25).
    Therefore, based on the information above, we identify the presence 
of a wide range of invertebrate prey, including flying and ground- and 
vegetation-dwelling species of terrestrial and aquatic origins to be an 
essential physical or biological feature of flycatcher habitat.
Water
    Flycatcher nesting habitat is largely associated with perennial 
(persistent) stream flow that can support the expanse of vegetation 
characteristics needed by breeding flycatchers, but there are 
exceptions. Flycatcher nesting habitat can persist on intermittent 
(ephemeral) streams that retain local conditions favorable to riparian 
vegetation (Service 2002, p. D-12). The range and variety of stream 
flow conditions (frequency, magnitude, duration, and timing) (Poff et 
al. 1997, pp. 770-772) that will establish and maintain flycatcher 
habitat can arise in different types of both regulated and unregulated 
flow regimes throughout its range (Service 2002, p. D-12). Also, flow 
conditions that will establish and maintain flycatcher habitat can be 
achieved in regulated streams, depending on scale of operation and the 
interaction of the primary physical characteristics of the landscape 
(Service 2002, p. D-12).
    In the Southwest, hydrological conditions at a flycatcher breeding 
site can vary remarkably within a season and between years (Service 
2002, p. D-12). At some locations, particularly during drier years, 
water or saturated soil is only present early in the breeding season 
(May and part of June) (Service 2002, p. D-12). At other sites, 
vegetation may be immersed in standing water during a wet year, but be 
hundreds of meters from surface water in dry years (Service 2002, p. D-
12). This is particularly true of reservoir sites such as the Kern 
River at Lake Isabella, California; Roosevelt Lake, Arizona; and 
Elephant Butte Reservoir, New Mexico (Service 2002, p. D-12). 
Similarly, where a river channel has changed naturally, there may be a 
total absence of water or visibly saturated soil for several years. In 
such cases, the riparian vegetation and any flycatchers breeding within 
it may persist for several years (Service 2002, p. D-12).
    In some areas, natural or managed hydrologic cycles can create 
temporary flycatcher 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 in the cycle. Some dam operations create varied 
situations that allow different plant species to thrive when water is 
released below a dam, held in a lake, or removed from a lakebed, and 
consequently, varying degrees of flycatcher habitat are available as a 
result of dam operations (Service 2002, p. 33). The riparian vegetation 
that constitutes flycatcher breeding habitat requires substantial water 
(Service 2002, p. D-12). Because flycatcher breeding habitat is often 
where there is slow-moving or still water, these slow and still water 
conditions may also be important in influencing the production of 
insect prey base for flycatcher food (Service 2002, p. D-12). These 
slow-moving water situations can also be managed or mimicked through 
manipulated supplemental water originating from sources such as 
agricultural return flows or irrigation canals (Service 2002, p. D-15).
    Therefore, based on the information above, we identify flowing 
streams with a wide range of stream flow conditions that support 
expansive riparian vegetation as an essential physical or biological 
feature of flycatcher habitat. The most common stream flow conditions 
are largely perennial (persistent) stream flow with a natural 
hydrologic regime (frequency, magnitude, duration, and timing). 
However, in the Southwest, hydrological conditions can vary, causing 
some flows to be intermittent, but the floodplain can retain surface 
moisture conditions favorable to expansive and flourishing riparian 
vegetation. These appropriate conditions can be supported by managed 
water sources and hydrological cycles that mimic key components of the 
natural hydrologic cycle.
Sites for Germination or Seed Dispersal
    Subsurface hydrologic conditions may in some places (particularly 
at the more arid locations of the Southwest) be equally important to 
surface water conditions in determining riparian vegetation patterns 
(Lichivar and Wakely 2004, p. 92). Where groundwater levels are 
elevated to the point that riparian forest plants can directly access 
those waters, it can be an area for breeding, non-breeding, 
territorial, dispersing, foraging, and migrating flycatchers. Elevated 
groundwater helps create moist soil conditions believed to be important 
for nesting conditions and prey populations (Service 2002, pp. 11, 18), 
as further discussed below.
    Depth to groundwater plays an important part in the distribution of 
riparian vegetation (Arizona Department of Water Resources 1994, p. 31) 
and consequently, flycatcher habitat. The

[[Page 50550]]

greater the depth to groundwater below the land surface, the less 
abundant the riparian vegetation (Arizona Department of Water Resources 
1994, p. 31). Localized, perched aquifers (a saturated area that sits 
above the main water table) can and do support some riparian habitat, 
but these systems are not extensive (Arizona Department of Water 
Resources 1994, p. 31).
    The abundance and distribution of fine sediment deposited on 
floodplains is critical for the development, abundance, distribution, 
maintenance, and germination of the plants that grow into flycatcher 
habitat (Service 2002, p. 16). Fine sediments provide seed beds to 
facilitate the growth of riparian vegetation for flycatcher habitat. In 
almost all cases, moist or saturated soil is present at or near 
breeding sites during wet and non-drought years (Service 2002, p. 11). 
The saturated soil and adjacent surface water may be present early in 
the breeding season, but only damp soil is present by late June or 
early July (Service 2002, p. D-3). Microclimate features (temperature 
and humidity) facilitated by moist or saturated soil, are believed to 
play an important role where flycatchers are detected and nest, their 
breeding success, and availability and abundance of food resources 
(Service 2002, pp. 18, D-12).
    Therefore, based on the information above, we identify elevated 
subsurface groundwater tables and appropriate floodplain fine sediments 
as essential physical or biological features of flycatcher habitat. 
These features provide water and seedbeds for the germination, growth, 
and maintenance of expansive growth of riparian vegetation needed by 
the flycatcher.

Cover or Shelter

    Riparian vegetation (described more in detail within the Sites for 
Breeding or Rearing (or Development) of Offspring section) also 
provides the flycatcher cover and shelter while migrating and nesting. 
Placing nests in dense vegetation provides cover and shelter from 
predators or nest parasites that would seek out flycatcher adults, 
nestlings, or eggs. Similarly, using riparian vegetation for cover and 
shelter during migration provides food-rich stopover areas, a place to 
rest, and shelter or cover along migratory flights (Service 2002, pp. 
D-14, F-16). Riparian vegetation used by migrating flycatchers can 
sometimes be less dense and abundant than areas used for nesting 
(Service 2002, p. D-19). However, migration stopover areas, even though 
not used for breeding, may be critically important resources affecting 
local and regional flycatcher productivity and survival (Service 2002, 
p. D-19).
    Therefore, based on the information above, we identify riparian 
tree and shrub species (described in more detail below) that provide 
cover and shelter for nesting, breeding, foraging, dispersing, and 
migrating flycatchers as essential physical or biological features of 
flycatcher habitat.

Sites for Breeding, Reproduction, or Rearing (or Development) of 
Offspring

Reproduction and Rearing of Offspring
    Riparian habitat characteristics such as dominant plant species, 
size and shape of habitat patches, tree canopy structure, vegetation 
height, and vegetation density are important parameters of flycatcher 
breeding habitat, although they may vary widely at different sites 
(Service 2002, p. D-1). The accumulating knowledge of flycatcher 
breeding sites reveals important areas of similarity, which constitute 
the basic concept of what is suitable breeding habitat (Service 2002, 
p. D-2). These habitat features are generally discussed below.
    Flycatchers nest in thickets of trees and shrubs ranging in height 
from 2 m to 30 m (6 to 98 ft) (Service 2002, p. D-3). Lower-stature 
thickets (2-4 m or 6-13 ft tall) te