Endangered and Threatened Wildlife and Plants; Critical Habitat Designation for the Cape Sable Seaside Sparrow, 63980-64002 [06-8930]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 71, Number 210 (Tuesday, October 31, 2006)]
[Proposed Rules]
[Pages 63980-64002]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-8930]



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Part III





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; Critical Habitat 
Designation for the Cape Sable Seaside Sparrow; Proposed Rule

Federal Register / Vol. 71, No. 210 / Tuesday, October 31, 2006 / 
Proposed Rules

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AU79


Endangered and Threatened Wildlife and Plants; Critical Habitat 
Designation for the Cape Sable Seaside Sparrow

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 endangered Cape Sable seaside sparrow 
(Ammodramus maritimus mirabilis) under the Endangered Species Act of 
1973, as amended (Act). In total, approximately 156,350 acres (ac) 
(63,273 hectares (ha)) fall within the boundaries of the proposed 
critical habitat designation. The proposed critical habitat is located 
in Miami-Dade and Monroe counties, Florida.

DATES: We will accept comments from all interested parties until 
January 2, 2007. We must receive requests for public hearings, in 
writing, at the address shown in the ADDRESSES section by December 15, 
2006.

ADDRESSES: If you wish to comment, you may submit comments and 
materials concerning this proposal by any one of several methods:
    1. You may submit written comments and information by mail or hand-
delivery to Tylan Dean, U.S. Fish and Wildlife Service, South Florida 
Ecological Services Office, 1339 20th Street, Vero Beach, Florida 
32960.
    2. You may send comments by electronic mail (e-mail) to Tylan--
Dean@fws.gov. Please see the Public Comments Solicited section below 
for file format and other information about electronic filing.
    3. You may fax your comments to 772-562-4288.
    4. You may submit comments via the Federal eRulemaking Portal: 
https://www.regulations.gov. Follow the instructions for submitting 
comments.
    Comments and materials received, as well as supporting 
documentation used in the preparation of this proposed rule, will be 
available for public inspection, by appointment, during normal business 
hours at the South Florida Ecological Services Office, 1339 20th 
Street, Vero Beach, Florida (telephone 772-562-3909).

FOR FURTHER INFORMATION CONTACT: Tylan Dean, South Florida Ecological 
Services Office (see ADDRESSES); telephone 772-562-3909; facsimile 772-
562-4288. Persons who use a telecommunications device for the deaf 
(TDD) may call the Federal Information Relay Service (FIRS) at 800-877-
8339, 7 days a week and 24 hours a day.

SUPPLEMENTARY INFORMATION:

Public Comments Solicited

    We intend that any final action resulting from this proposal will 
be as accurate and as effective as possible. Therefore, comments or 
suggestions from the public, other concerned governmental agencies, the 
scientific community, industry, or any other interested party 
concerning this proposed rule are hereby solicited. Comments 
particularly are sought concerning:
    (1) The reasons any habitat should or should not be determined to 
be critical habitat as provided by section 4 of the Act (16 U.S.C. 1531 
et seq.), including whether the benefit of designation will outweigh 
any threats to the species due to designation;
    (2) Specific information on the amount and distribution of Cape 
Sable seaside sparrow habitat, including areas occupied by Cape Sable 
seaside sparrows at the time of listing and containing features 
essential to the conservation of the species, and areas not occupied at 
the time of listing that are essential to the conservation of the 
species;
    (3) Land use designations and current or planned activities in the 
subject areas and their possible impacts on proposed critical habitat;
    (4) Any foreseeable economic, national security, or other potential 
impacts resulting from the proposed designation and, in particular, any 
impacts on small entities; and
    (5) Whether our approach to designating critical habitat could be 
improved or modified in any way to provide for greater public 
participation and understanding, or to assist us in accommodating 
public concerns and comments.
    If you wish to comment, you may submit your comments and materials 
concerning this proposal by any one of several methods (see ADDRESSES). 
Please submit electronic comments to tylan_dean@fws.gov in ASCII file 
format and avoid the use of special characters or any form of 
encryption. Please also include ``Attn: Cape Sable seaside sparrow'' in 
your e-mail subject header and your name and return address in the body 
of your message. If you do not receive a confirmation from the system 
that we have received your message, contact us directly by calling our 
South Florida Ecological Services Office at 772-562-3909.
    Our practice is to make comments, including names and home 
addresses of respondents, available for public review during regular 
business hours. Individual respondents may request that we withhold 
their names and home addresses, etc., but if you wish us to consider 
withholding this information, you must state this prominently at the 
beginning of your comments. In addition, you must present rationale for 
withholding this information. This rationale must demonstrate that 
disclosure would constitute a clearly unwarranted invasion of privacy. 
Unsupported assertions will not meet this burden. In the absence of 
exceptional, documentable circumstances, this information will be 
released. We will always make submissions from organizations or 
businesses, and from individuals identifying themselves as 
representatives of or officials of organizations or businesses, 
available for public inspection in their entirety.

Role of Critical Habitat in Actual Practice of Administering and 
Implementing the Act

    Attention to and protection of habitat is paramount to successful 
conservation actions. The role that designation of critical habitat 
plays in protecting habitat of listed species, however, is often 
misunderstood. As discussed in more detail below in the discussion of 
exclusions under the Act's section 4(b)(2), there are significant 
limitations on the regulatory effect of designation under section 
7(a)(2) of the Act. In brief, (1) designation provides additional 
protection to habitat only where there is a Federal nexus; (2) the 
protection is relevant only when, in the absence of designation, 
destruction or adverse modification of the critical habitat would take 
place (in other words, other statutory or regulatory protections, 
policies, or other factors relevant to agency decision-making would not 
prevent the destruction or adverse modification); and (3) designation 
of critical habitat triggers the prohibition of destruction or adverse 
modification of that habitat, but it does not require specific actions 
to restore or improve habitat.
    Currently, only 475 species, or 36 percent of the 1,311 listed 
species in the United States under the jurisdiction of the Service, 
have designated critical habitat. We address the habitat needs of all 
1,311 listed species through conservation mechanisms such as listing, 
section 7 consultations, the section 4 recovery planning process, the

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section 9 protective prohibitions of unauthorized take, section 6 
funding to the States, the section 10 incidental take permit process, 
and cooperative, nonregulatory efforts with private landowners. The 
Service believes that it is these measures that may make the difference 
between extinction and survival for many species.
    In considering exclusions of areas proposed for designation, we 
evaluated the benefits of designation in light of Gifford Pinchot Task 
Force v. U.S. Fish and Wildlife Service, 378 F. 3d 1059 (9th Cir 2004). 
In that case, the Ninth Circuit invalidated the Service's regulation 
defining ``destruction or adverse modification of critical habitat.'' 
In response, on December 9, 2004, the Director issued guidance to be 
considered in making section 7 adverse modification determinations. 
This proposed critical habitat designation does not use the invalidated 
regulation in our consideration of the benefits of including areas in 
this final designation. The Service will carefully manage future 
consultations that analyze impacts to designated critical habitat, 
particularly those that appear to be resulting in an adverse 
modification determination. Such consultations will be reviewed by the 
Regional Office prior to finalizing to ensure that an adequate analysis 
has been conducted that is informed by the Director's guidance.
    On the other hand, to the extent that designation of critical 
habitat provides protection, that protection can come at significant 
social and economic cost. In addition, the mere administrative process 
of designation of critical habitat is expensive, time-consuming, and 
controversial. The current statutory framework of critical habitat, 
combined with past judicial interpretations of the statute, make 
critical habitat the subject of excessive litigation. As a result, 
critical habitat designations are driven by litigation and courts 
rather than biology, and made at a time and under a time frame that 
limits our ability to obtain and evaluate the scientific and other 
information required to make the designation most meaningful.
    In light of these circumstances, the Service believes that 
additional agency discretion would allow our focus to return to those 
actions that provide the greatest benefit to the species most in need 
of protection.

Procedural and Resource Difficulties in Designating Critical Habitat

    We have been inundated with lawsuits for our failure to designate 
critical habitat, and we face a growing number of lawsuits challenging 
critical habitat determinations once they are made. These lawsuits have 
subjected the Service to an ever-increasing series of court orders and 
court-approved settlement agreements, compliance with which now 
consumes nearly the entire listing program budget. This leaves the 
Service with little ability to prioritize its activities to direct 
scarce listing resources to the listing program actions with the most 
biologically urgent species conservation needs.
    The consequence of the critical habitat litigation activity is that 
limited listing funds are used to defend active lawsuits, to respond to 
Notices of Intent to sue relative to critical habitat, and to comply 
with the growing number of adverse court orders. As a result, listing 
petition responses, the Service's own proposals to list critically 
imperiled species, and final listing determinations on existing 
proposals are all significantly delayed.
    The accelerated schedules of court-ordered designations have left 
the Service with limited ability to provide for public participation or 
to ensure a defect-free rulemaking process before making decisions on 
listing and critical habitat proposals, due to the risks associated 
with noncompliance with judicially imposed deadlines. This in turn 
fosters a second round of litigation in which those who fear adverse 
impacts from critical habitat designations challenge those 
designations. The cycle of litigation appears endless and is expensive, 
thus diverting resources from conservation actions that may provide 
relatively more benefit to imperiled species.
    The costs resulting from the designation include legal costs, the 
cost of preparation and publication of the designation, the analysis of 
the economic effects and the cost of requesting and responding to 
public comment, and in some cases the costs of compliance with the 
National Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.). These 
costs, which are not required for many other conservation actions, 
directly reduce the funds available for direct and tangible 
conservation actions.

Background

    We intend to discuss topics directly relevant to the designation of 
critical habitat in this proposed rule. Additional topics may be found 
under the ``Primary Constituent Elements'' discussion. For more 
information on the Cape Sable seaside sparrow, including 
characteristics and life history, refer to the South Florida Multi-
Species Recovery Plan, available at the South Florida Ecological 
Services Web site https://www.fws.gov/verobeach.
    The Cape Sable seaside sparrow is one of eight extant subspecies of 
seaside sparrow. Its distribution is limited to the short-hydroperiod 
wetlands at the downstream end of the greater Everglades system on the 
southern tip of mainland Florida. Unlike most other subspecies of 
seaside sparrow, which occupy primarily brackish tidal systems (Post 
and Greenlaw 1994, p. 4), the Cape Sable seaside sparrow currently 
occurs primarily in the short-hydroperiod freshwater wet prairies, also 
referred to as marl prairies, though it still occupies brackish marshes 
in some areas.
    The Cape Sable seaside sparrow is generally sedentary, secretive, 
and non-migratory, and it occupies the marl prairies of southern 
Florida year-round. During the breeding season (March to August), male 
sparrows establish and defend territories that are variable in size, 
with average sizes ranging from 2.2 to 8.9 ac (0.9 to 3.6 ha) within 
different sites and years (Werner and Woolfenden 1983, p. 67; Pimm et 
al. 2002, p. 18). Sparrows are monogamous (Post and Greenlaw 1994, p. 
10), with a single female occurring within a male's breeding territory. 
Throughout the breeding season, the majority of a sparrow pair's 
activities occur within this territory, including breeding, feeding, 
and sheltering. Outside of the breeding season, sparrows generally 
remain sedentary in the same general vicinity of their breeding 
territories, but occupy a larger area than the breeding season 
territory. Average non-breeding season home range size was 
approximately 42.1 ac (17.1 ha) and ranged from 14.1 to 137.1 ac (5.7 
to 55.5 ha) (Dean and Morrison 2001, p. 36). Some individuals make 
exploratory movements away from their territories and may occasionally 
relocate their territories and home ranges before again resuming a 
sedentary movement pattern (Dean and Morrison 2001, p. 36).
    Sparrows are generally short-lived, with an average individual 
annual survival rate of 66 percent (Lockwood et al. 2001, p. 278). The 
average lifespan is probably 2 to 3 years. Consequently, a sparrow 
population requires favorable breeding conditions in most years to be 
self-sustaining and cannot persist under poor conditions for extended 
periods (Lockwood et al. 1997, p. 729; Lockwood et al. 2001, p. 281; 
Pimm et al. 2002, p. 74).
    Sparrows generally begin nesting in early March (Lockwood et al. 
2001, p. 278), but they may begin territorial behavior, courtship, and 
nest-building in late February (Werner and Woolfenden 1983, p. 64; 
Lockwood et al. 1997, p. 722). This timing coincides with the dry 
season, and most areas

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within the marl prairies are either dry or only shallowly inundated at 
the beginning of the breeding season. Sparrows build nests above the 
ground surface, typically 6.7 to 7.1 inches (in) (17 to 18 centimeters 
(cm)) over the ground (Werner 1975, p. 147; Lockwood et al. 2001, p. 
278). Nests are woven into clumps of dense vegetation and are well-
concealed (Werner 1975, p. 145; Post and Greenlaw 1994, p. 14). Nest 
cups are consistently concealed from above (Post and Greenlaw 1994, p. 
13), either through construction of a domed cover or through modifying 
vegetation in the vicinity (Werner 1975, p. 142; Post and Greenlaw 
1994, pp. 13-14). The sparrow nesting cycle, from nest construction to 
independence of young, lasts approximately 30 to 50 days (Werner 1975, 
p. 163; Lockwood et al. 2001, p. 278), and sparrows may renest 
following both successful and failed nesting attempts (Werner 1975, p. 
163; Post and Greenlaw 1994, p. 13; Lockwood et al. 2001, p. 278). 
Because of the long breeding season in southern Florida, sparrows 
regularly nest several times within a year and may be capable of 
successfully fledging 2 to 4 clutches, though few sparrows probably 
reach this level of success (Lockwood et al. 2001, p. 278). Second and 
third nesting attempts may occur during the early portion of the wet 
season, and nests later in the season occur over water. The height of 
nests above ground surface increases after water levels rise, and 
average height of late-season nests is 8.3 in (21 cm) above ground 
surface (Lockwood et al. 2001, p. 278).
    Nest success rates vary among years and range from 12 to 53 percent 
(Lockwood et al. 2001, p. 278). Nest predation is the primary 
documented cause of nest failure (Pimm et al. 2002, p. 23), accounting 
for more than 75 percent of all nest failures (Lockwood et al. 1997, p. 
723). Unlike many other wetland species, nest predation rates for 
sparrows are lowest under dry conditions. As water levels begin to rise 
above ground surface with the onset of the summer rains in May or June, 
nests become more detectable, and therefore, nest predation rates also 
rise. Nests that are active after June 1, when water levels are above 
ground, are more than twice as likely to fail as nests during drier 
periods (Lockwood et al. 2001, p. 278). This effect appears to be a 
result of both increased likelihood of nests being flooded and an 
increased likelihood of predation (Lockwood et al. 1997, p. 724; 
Lockwood et al. 2001, p. 278; Pimm et al. 2002, p. 25).
    The Cape Sable seaside sparrow was first discovered in the 
cordgrass (Spartina spp.) marshes on Cape Sable in 1918 and was 
originally thought to be limited in distribution to Cape Sable (Howell 
1919, p.87). On September 2, 1935, a severe hurricane struck the Keys 
and southern Florida, with the hurricane's center passing within a few 
miles of Cape Sable (Stimson 1956, p. 490). Post-hurricane observations 
suggested that, in the vicinity of Cape Sable, water levels resulting 
from the storm surge rose approximately 8 feet (ft) (2.4 meters (m)) 
above normal water levels, and the sparrow was thought to have 
disappeared from the area as a result of the storm, despite occasional 
reports of sparrows that could not be verified (Stimson 1956, p. 492). 
Between 1935 and the 1950s, searches on Cape Sable failed to locate 
sparrows (Stimson 1956, p. 492). Despite the fact that sparrows were 
again reported on Cape Sable in 1970 (Kushlan and Bass 1983, p. 140; 
Werner and Woolfenden 1983, p. 57), the habitat in the area had been 
changing significantly from cordgrass marshes to mangroves and mud 
flats since the 1935 hurricane, and sparrows are considered to have 
been extirpated from this area since 1981 (Kushlan and Bass 1983, p. 
142).
    In 1928, Cape Sable seaside sparrows were reported to the northwest 
of Pinecrest, along the western mainland coast of Florida, in the 
vicinity of what is today Everglades City (Nicholson 1928, p. 237). The 
location of this mainland record was improperly reported, and the true 
location was not accurately reported until 1954 (Sprunt 1954, p. 479). 
Stimson conducted extensive searches on the Florida mainland in the 
vicinity of the corrected 1928 sparrow observation and found sparrows 
to be widespread throughout both coastal cordgrass (reported as S. 
patens, but probably S. bakeri) (Werner and Woolfenden 1983, p. 60) 
marshes and freshwater prairies along the western edge of the 
Everglades (Stimson 1956, p. 490). However, by 1968, Stimson (1968, p. 
867) concluded that widespread fires in this region had severely 
impacted the sparrows in that area, and he expected them to be 
extirpated from the area as a result.
    In the early 1940s, Anderson (1942, p. 12) reported sparrows in the 
coastal marshes in the vicinity of Ochopee. Subsequent searches 
revealed that sparrows occurred south of Ochopee along the coastal 
marshes landward of the mangrove zone (Stimson 1956, p. 492). Werner 
(1975, p. 42) reported that habitat occupied by sparrows in the Ochopee 
area was changing from cordgrass marshes to other species, and 
mangroves were encroaching into the area. Werner's searches in the area 
from 1970 through 1975 (Werner 1975, p. 42) revealed a decline in the 
number of sparrows and the amount of habitat available in the area. 
Sparrows were extirpated from this area by 1981 (Kushlan and Bass 1983, 
p. 143), and there is little or no remaining suitable habitat in the 
area.
    Within the last 20 years, sparrows have consistently occurred 
within the marl prairies that have had appropriate hydrologic and 
vegetation conditions over time. There are six spatially distinct 
regions across the southern Everglades where sparrows currently occur, 
and these same areas have consistently supported the sparrow 
population. These regions are separated from each other by areas of 
unsuitable habitat, such as the forested communities of Long Pine Key, 
the deep-water slough communities of Shark River Slough and Taylor 
Slough, and other areas that do not support the specific conditions 
that sparrows require. The distances between these regions range from 2 
to 20 miles (mi) (3.2 to 32.2 kilometer (km)), and sparrows rarely move 
among the regions (Walters et al. 2000, p. 1107; Lockwood et al. 2001, 
p. 279), though some such movements have now been documented (Lockwood 
2006, p. 2). For the last 20 years, these areas have been commonly 
referred to as sparrow subpopulations A through F (Pimm et al. 2002, p. 
69).
    In 1972, Cape Sable seaside sparrows were discovered in the 
vicinity of Taylor Slough, in what is today known as subpopulation C, 
east of Shark River Slough (Ogden 1972, p. 852; see the individual 
units descriptions in the Proposed Critical Habitat section for 
identification of the subpopulations). Subsequent investigation 
revealed that a sparrow had been reported to Everglades National Park 
(ENP) in this area in 1958, but the observation was never verified 
(Werner 1975, p. 32; Pimm et al. 2002, p. 10). Surveys conducted with 
the use of a helicopter by Werner in 1974 and 1975 sought to 
characterize the distribution and abundance of sparrows in this region. 
These initial surveys revealed that sparrows were widely distributed 
and abundant (Werner 1975, p. 32). The sparrow locations reported 
included locations within what are today known as subpopulations B, C, 
D, E, and F. They occupied an area of approximately 21,745 to 31,629 ac 
(8,800 to 12,800 ha), and the number of sparrows occurring within this 
area was estimated to range from 1,500 to 26,300 individuals (Werner 
1975, p. 32). Because of the magnitude of the area occupied and the 
large estimates of population size, ecologists concluded that sparrows 
probably occurred within this area for

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many years. The difficulty in accessing the areas and the vastness of 
the areas (Kushlan and Bass 1983, p. 145), as well as the secretiveness 
of the sparrow, all contributed to the failure to document the 
sparrow's occurrence in the area previously. The sparrow populations 
within these areas probably fluctuated over time in response to changes 
in habitat suitability resulting from fires and hydrologic conditions 
(Taylor 1983, p. 148; Kushlan and Bass 1983, p. 145). These 
fluctuations may have also contributed to the lack of sparrow 
detections in these areas previously.
    Throughout the known history of the Cape Sable seaside sparrow, the 
species has been recognized to associate with either of two vegetation 
communities: (1) The cordgrass marshes that are partly tidally 
influenced and occur within a narrow band of the coast just landward 
from the mangrove communities, and (2) the short-hydroperiod freshwater 
marl prairies that flank the deeper sloughs of the southern Everglades. 
The tidally influenced cordgrass marshes constitute typical seaside 
sparrow habitat (Post and Greenlaw 1994, p. 3). Occurrence year-round 
within the freshwater marl prairies is relatively unique among seaside 
sparrows, with only the now-extinct dusky seaside sparrow (Ammodramus 
maritimus nigrescens) exhibiting a similar habitat affinity; in those 
freshwater areas occupied by the dusky seaside sparrow, the habitat was 
still primarily composed of cordgrass (Post and Greenlaw 1994, p. 4). 
The freshwater habitats occupied by the Cape Sable seaside sparrow are 
not dominated by cordgrass; the most commonly associated species 
reported is muhly grass (Muhlenbergia filipes) (Werner 1975, p. 77; 
Kushlan and Bass 1983, p. 145; Werner and Woolfenden 1983, p. 59; Post 
and Greenlaw 1994, p. 4). However, a variety of vegetation species 
occurs within the freshwater marl prairies occupied by Cape Sable 
seaside sparrows, including vegetation from which Muhlenbergia is 
absent (Ross et al. 2006, pp. 7-16). Other dominant species that occur 
in these prairies include sawgrass (Cladium jamaicense), Florida little 
bluestem (Schizachyrium rhizomatum), black-topped sedge (Schoenus 
nigricans), and beak rushes (Rhynchospora spp.) (Werner and Woolfenden 
1983, pp. 57-61; Ross et al. 2006, pp. 6-16).
    Cape Sable seaside sparrows occupy the above two community types 
year-round, and the vegetation must support all sparrow life stages. 
Sparrows occur in the heart of the expansive Everglades wetland system, 
in a harsh environment where flooding, fires, and high temperatures 
occur regularly. During periods when the plant communities are dry, 
usually coinciding with the early winter and late spring (December to 
May), sparrows travel across the ground beneath the grasses and only 
occasionally perch on the vegetation. During the wet season (June to 
November), these areas are continually inundated, with peak water 
depths occasionally exceeding 2 ft (0.6 m) (Nott et al. 1998, p. 26). 
During these periods, sparrows travel within the grass, perching low in 
the clumps, hopping among the bases of dense grass clumps, and walking 
over matted grass. They fly more frequently and regularly perch low in 
the vegetation, but they generally remain extremely inconspicuous (Dean 
and Morrison 2001, p. 51).
    Periphyton is another important characteristic of sparrow habitat. 
Periphyton is a complex matrix of calcitic algae and associated organic 
detritus that plays an important role in the development of soils 
within the marl prairies (Davis et al. 2005, p. 825). During wet 
periods, a periphyton mat forms on all submerged substrates, including 
underlying limestone and vegetation stems. Marl soil accretion is 
directly related to the extent and productivity of periphyton (Davis et 
al. 2005, p. 825), and marl soils are consequently generally deeper in 
areas with longer hydroperiods. In some areas, a dense periphyton mat 
forms on the water surface and intertwines with the vegetation such 
that sparrows may be able to move across it under some conditions. 
These periphyton mats are an integral component of marl prairies and 
can affect the vegetation species and structure in an area and even the 
microclimate, which all relates to the suitability of an area for 
sparrows.
    Small tree islands and individual trees and shrubs occur throughout 
the areas occupied by the sparrows, but at a very low density. Sparrows 
do not require woody vegetation during any aspect of their normal 
behavior and generally avoid areas where shrubs and trees are either 
dense or evenly distributed. However, the small tree islands and 
scattered shrubs and trees may serve as refugia during extreme 
environmental conditions and may be used as escape cover when fleeing 
from potential predators (Dean and Morrison 2001, p. 38). Because of 
the sparrows' general aversion to dense trees and woody vegetation, 
encroaching trees and shrubs can quickly degrade potential habitat.
    After fires, sparrows do not regularly occupy burned areas for 2 to 
3 years (Pimm et al. 2002, p. 97; Lockwood et al. 2005, p. 10), though 
they can re-occupy areas after only one year under some conditions 
(Taylor 1983, p. 151; Werner and Woolfenden 1983, p. 62). This is 
probably a result of the sparrow's dependence on some level of 
structural complexity that must develop to provide cover, support 
nests, and allow them to move through the habitat during wet periods. 
Fire is not uncommon within the areas occupied by sparrows, and nearly 
all areas where sparrows currently occur have been burned within the 
past 10 to 20 years (Lockwood et al. 2003, p. 466). Large fires, such 
as the Ingraham fire of 1989, which burned approximately 98,842 ac 
(40,000 ha), pose a significant risk to sparrow subpopulations because 
they have the potential to render the habitat supporting several entire 
sparrow subpopulations unsuitable for 2 to 3 years or more (Lockwood et 
al. 2003, p. 467). A combination of naturally ignited and human-ignited 
(prescribed, arson, or accidental) fires have resulted in different 
fire frequencies in different portions of the sparrow's range. Most of 
the plant species that occur within sparrow habitat are fire-adapted 
and respond quickly following fire (Snyder 2003, pp. 203-204). Several 
of the dominant grass species, including Muhlenbergia, also flower 
primarily following fires during the growing season (Main and Barry 
2002, p. 433). Under normal conditions, fires do not kill the 
individual plants that make up the dominant species in sparrow habitat, 
and fires only remove the above-ground growth and leaf litter (Snyder 
and Schaeffer 2004). The plant species rapidly respond, sprout quickly 
following fire, and grow rapidly. Many of the dominant grasses may grow 
more than 15 in (38 cm) after only a few weeks (Steward and Ornes 1975, 
p. 167; Snyder 2003, pp. 203-204). For this reason, the species 
composition and even the general structural characteristics of the 
vegetation may be nearly indistinguishable from unburned areas only 2 
to 3 years after burning (Lockwood et al. 2005, pp. 8-9). Under 
unfavorable conditions such as extreme wet or dry periods, vegetation 
recovery from fire may be prolonged, and both species composition and 
structure may be affected.
    Hydrology of the area is an important component of the habitat. In 
addition to directly affecting the sparrow and its ability to forage, 
move within habitat, and nest, hydrologic patterns largely dictate the 
plant community composition, and even the fire frequency. Ross et al. 
(2006) have investigated the relationship between vegetation species 
composition and hydroperiods. Their preliminary results

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indicate that hydroperiods in the range of 90 to 270 days support the 
plant species upon which sparrows primarily depend (Ross et al. 2006, 
pp. 14, 40). Longer hydroperiods result in such unfavorable habitat 
conditions as dense, continuous growth of sawgrass or spike rushes 
(Eleocharis spp.) that sparrows do not occupy. Shorter hydroperiods may 
allow encroachment of woody species and may have an elevated potential 
of fire (Davis et al. 2005, p. 828). Within this optimal inundation 
duration, several different vegetation associations may result, but 
most are used regularly by sparrows. The local variability across the 
landscape within areas where sparrows occur produces a heterogeneous 
arrangement of vegetation conditions that provide habitat for sparrows 
during some environmental conditions. A complex relationship between 
hydrologic conditions, fire history, and soil depth determines the 
specific vegetation conditions at a site, and variation in these 
characteristics may result in a complex mosaic of vegetation 
characteristics (Taylor 1983, p. 152; Ross et al. 2006, pp. 1-46). This 
variability is characteristic of these habitats.
    Average annual rainfall in the Everglades is approximately 56 in 
(142 cm) (ENP 2005, p. 15), with the majority falling within the summer 
months, which coincides with the latter half of the sparrow nesting 
season. This rainfall has a strong influence on the hydrologic 
characteristics of the marl prairies. However, throughout southern 
Florida, including sparrow habitat, hydrologic conditions are also 
strongly influenced by water management actions. A complex system of 
canals, levees, pumps, and other water management structures, operated 
by complex operational rules, can have profound impacts on the 
hydrologic conditions throughout much of the remaining marl prairies 
(Johnson et al. 1988, p. 31; Van Lent and Johnson 1993, pp. 4-7; Pimm 
et al. 2002, p. 106).
    The interaction of fire and flooding also strongly influences the 
suitability of habitat for sparrows. In the most extreme case, the 
vegetation in areas that burn and are subsequently flooded within 1 to 
3 weeks after the fire, either as a result of a natural rainfall event 
or human-caused hydrologic changes, may not recover for a long period, 
possibly 10 years or more (Ross 2006). Alternatively, if water levels 
overtop the sprouting grasses, the grasses may die, resulting in an 
absence of vegetation. Recovery of vegetation from these circumstances 
has to result from seed germination, which requires a much longer time 
for recovery and may result in a different plant species composition 
and structure from the vegetation that was present prior to the fire. 
Under less extreme conditions, vegetation may recover following fire 
more quickly when water levels are near the soil surface, providing 
ample water for the plants.
    The six distinct areas that Cape Sable seaside sparrows occupy have 
different environmental conditions that affect the likelihood of 
flooding and fire. Areas of sparrow habitat that are at higher 
elevation or in areas that tend to be overdrained, such as some areas 
proximate to urban and agricultural areas (Van Lent and Johnson 1993, 
p. 5), are consequently more likely to burn under dry conditions, but 
may be more likely to be favorable to sparrows under very wet 
conditions. Similarly, areas of sparrow habitat that are immediately 
downstream from water control structures and in relatively low-lying 
areas are generally less likely to burn frequently (Ross et al. 2006, 
p. 43), but they may be more subject to damaging water levels than 
other areas during wet periods (Nott et al. 1998, p. 31; Pimm et al. 
2002, p. 107). This variability in the physical and environmental 
characteristics among areas occupied by the sparrows, in addition to 
the local meteorological variability within the region, may help 
maintain the sparrow population over time.

Previous Federal Actions

    On March 11, 1967 (32 FR 4001), the Cape Sable seaside sparrow was 
determined to be ``threatened with extinction,'' and was conferred 
protection under the Endangered Species Preservation Act (Pub. L. 89-
669). The Cape Sable seaside sparrow was subsequently added to the list 
of species protected under the Endangered Species Conservation Act of 
1969 (Pub. L. 91-135), and all species listed on the Conservation Act 
were adopted by the Act in 1973 and assigned to endangered status. 
Critical habitat was designated for the Cape Sable seaside sparrow on 
August 11, 1977 (42 FR 40685) and was corrected on September 22, 1977 
(42 FR 47840). The 1977 critical habitat designation for Cape Sable 
seaside sparrow encompasses approximately 197,260 ac (79,828 ha). The 
first recovery plan for the sparrow was completed in April 1983. A 
revised recovery plan for the sparrow was finalized in May 1999. On 
August 26, 1999, Sidney Maddock, Biodiversity Legal Foundation, 
submitted a petition to the Service, on behalf of himself, the 
Biodiversity Legal Foundation, the Florida Biodiversity Project, Brian 
Scherf, and Rosalyn Scherf, to revise critical habitat for the Cape 
Sable seaside sparrow. On July 10, 2000 (65 FR 42316), we published a 
90-day finding in which we determined that the petition presented 
substantial information indicating that revision may be warranted. On 
October 23, 2001 (65 FR 53573), we published a 12-month finding in 
which we announced that revision of critical habitat may be warranted 
as a result of detailed new information about sparrow distribution and 
ecology that had been obtained since critical habitat was originally 
designated. We concluded that some new areas would likely need to be 
added and some removed from the critical habitat designation. For more 
information on previous Federal actions, including the rationale for 
revising critical habitat, refer to that 12-month finding.
    Until now, work on the revision of critical habitat for the Cape 
Sable seaside sparrow has been precluded due to other, higher priority 
listing and critical habitat actions. On December 20, 2000, a lawsuit 
was filed in the U.S. District Court for the District of Columbia 
alleging that the Service had not complied with the Act by failing to 
issue a 12-month finding as to how it planned to proceed with the 
petitioned revision to critical habitat and that the revision was 
withheld or unreasonably delayed under the Administrative Procedure Act 
(5 U.S.C. 551 et seq.). On September 30, 2003, the Court ruled that the 
Service complied with the Act by issuing the finding (see above), and 
was exercising reasonable discretion in postponing developing a 
proposed rule to revise critical habitat (Biodiversity Legal Foundation 
v. Norton, 285 F. Supp. 2d (D.D.C. 2003)). However, it ordered the 
Service to specify a date on which we would begin work on a rule to 
revise critical habitat for the Cape Sable seaside sparrow and estimate 
how long the process would take. On November 28, 2003, the Service 
notified the Court that a proposed rule to revise the critical habitat 
would be submitted to the Federal Register by October 24, 2006, and a 
final rule would be completed within 12 months of the publication of 
the proposed rule.

Critical Habitat

    Critical habitat is defined in section 3 of the Act as: (i) The 
specific areas within the geographical area occupied by a species at 
the time it is listed in accordance with the Act, on which are found 
those physical or biological features (I) essential to the conservation 
of the species and (II) that may require special management 
considerations or

[[Page 63985]]

protection; and (ii) specific areas outside the geographical area 
occupied by a 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 any 
endangered or threatened species to the point at which the measures 
provided pursuant to the Act are no longer necessary.
    Critical habitat receives protection under section 7 of the Act 
through the prohibition against destruction or adverse modification of 
critical habitat with regard to actions carried out, funded, or 
authorized by a Federal agency. Section 7 requires consultation on 
Federal actions that are 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 government or public access to private lands.
    To be included in a critical habitat designation, the habitat 
within the area occupied by the species must first have features that 
are essential to the conservation of the species. Critical habitat 
designations identify, to the extent known using the best scientific 
data available, habitat areas that provide essential life cycle needs 
of the species (i.e., areas on which are found the primary constituent 
elements (PCEs), as defined at 50 CFR 424.12(b)).
    Habitat occupied at the time of listing may be included in critical 
habitat only if the essential features thereon may require special 
management or protection. Thus, we do not include areas where existing 
management is sufficient to conserve the species. [As discussed below, 
such areas may also be excluded from critical habitat under section 
4(b)(2) of the Act.] Furthermore, when the best available scientific 
data do not demonstrate that the conservation needs of the species 
require additional areas, we will not designate critical habitat in 
areas outside the geographical area occupied by the species at the time 
of listing. However, an area that was not known to be occupied at the 
time of listing but is currently occupied by the species will likely be 
essential to the conservation of the species and, therefore, typically 
included in the critical habitat designation.
    The Service's Policy on Information Standards Under the Act, 
published in the Federal Register on July 1, 1994 (59 FR 34271), and 
Section 515 of the Treasury and General Government Appropriations Act 
for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658) and the associated 
Information Quality Guidelines issued by the Service, provide criteria, 
establish procedures, and provide guidance to ensure that decisions 
made by the Service represent the best scientific data available. They 
require Service 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 determining which areas are critical 
habitat, a primary source of information is generally the listing 
package for the species. Additional information sources 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. All information is 
used in accordance with the provisions of Section 515 of the Treasury 
and General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 
106-554; H.R. 5658) and the associated Information Quality Guidelines 
issued by the Service.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific data available. Habitat is often 
dynamic, and species may move from one area to another over time. 
Furthermore, we recognize that designation of critical habitat may not 
include all of the habitat areas that may eventually be determined to 
be necessary for the recovery of the species. For these reasons, 
critical habitat designations do not signal that habitat outside the 
designation is unimportant or may not be required for recovery.
    Areas that support populations, but are outside the critical 
habitat designation, will continue to be subject to conservation 
actions implemented under section 7(a)(1) of the Act and to the 
regulatory protections afforded by the section 7(a)(2) jeopardy 
standard, as determined on the basis of the best available information 
at the time of the action. Federally funded or permitted projects 
affecting listed species outside their designated critical habitat 
areas may still result in jeopardy findings in some cases. 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 
(HCP), or other species conservation planning efforts if new 
information available to these planning efforts calls for a different 
outcome.

Methods

    As required by section 4(b) of the Act, we used the best scientific 
data available in determining areas that contain the physical and 
biological features that are essential to the conservation of the Cape 
Sable seaside sparrow and other areas that are essential to the 
conservation of the sparrow. We reviewed all available published and 
unpublished literature about the ecology of the sparrow, including the 
1999 petition and supporting information provided with it. We reviewed 
the revised recovery plan (Service 1999a) for the sparrow, as well as 
the previous recovery plan (Service 1983). We evaluated management 
plans that address specific management needs of sparrows and their 
habitats and past section 7 consultations that addressed the needs of 
the sparrow, including the 1999 jeopardy biological opinion on Test 7 
of the Experimental Program of Water Deliveries (Service 1999b), and 
the reasonable and prudent measures that were implemented as a result 
of the biological opinion. We reviewed reports received from section 7 
consultations and from researchers who hold section 10(a)(1)(A) 
research permits. We reviewed past records of sparrow occurrence, 
distribution, and habitat use over time that were compiled by Florida 
Fish and Wildlife Conservation Commission (FWC) personnel, National 
Park Service (NPS) personnel, and independent researchers contracted by 
the Service and the NPS. We obtained spatial information on the 
location of sparrow occurrences recorded on surveys from 1981 to 
present and spatial data that reflect vegetation type, fire history, 
and hydrologic conditions within these areas. These data were entered 
into a geographic information system (GIS) for analysis. We reviewed 
information resulting from hydrologic modeling of several water 
management regimes that have been implemented in the region. We also 
evaluated the conclusions and recommendations that resulted from an 
independent peer review of the science related to sparrows and their 
management that was conducted by the American Ornithologists' Union in 
1999 (Walters et al. 2000), and the recommendations and conclusions of 
the 2003 South Florida Ecosystem Restoration Multi-species Avian 
Workshop (SEI 2003), which was held to develop a common understanding 
of how four avian species, including the Cape Sable

[[Page 63986]]

seaside sparrow, would respond to Everglades restoration.
    We have also reviewed available information on the habitat 
requirements of this species. In determining PCEs, we reviewed all 
available published and unpublished literature on the ecology, habitat 
needs, and factors limiting the sparrow's occurrence and distribution, 
including information in published, peer-reviewed journal articles; 
unpublished reports and theses; and preliminary results from ongoing 
research.
    The original critical habitat designation (August 11, 1977, 42 FR 
40685; corrected September 22, 1977, 42 FR 47840) was evaluated 
thoroughly during our analysis. However, the 1977 rule did not include 
the specific criteria used to delineate the boundaries of the original 
designation and did not identify any PCEs. Therefore, for this proposed 
rule, we chose to begin our analysis by considering historic habitat 
available to the species and habitat areas that support or have 
recently supported sparrows. All historical and recent locations of 
sparrow occurrences were mapped to better delineate sparrow habitat. 
Current and historical habitat data from several sources were also 
evaluated to identify areas outside of the known occupied range of the 
Cape Sable seaside sparrow that may support sparrows or have the 
potential to support sparrows. However, while historical habitat maps 
identified several areas outside of the known occupied range where 
sparrows may have occurred historically, these areas no longer contain 
habitat features that would support sparrows. Therefore, we do not 
propose as revised critical habitat any areas outside the geographical 
areas presently occupied by the species. For the purpose of this rule, 
areas presently occupied are those where sparrows have been recorded 
between 1981 and the present. We are not proposing to designate 
critical habitat on Cape Sable, in the Ochopee area, or in agricultural 
areas in the vicinity of Homestead where sparrows previously occurred.
    After considering these habitat areas, our efforts focused on 
identifying those areas occupied at the time of listing that contain 
the physical and biological features essential to the conservation of 
Cape Sable seaside sparrows and those other areas that are essential to 
the conservation of the Cape Sable seaside sparrow and are presently 
occupied. To determine critical habitat boundaries, we began with 
comprehensive surveys of sparrow habitat conducted from 1981 to 2006 to 
identify all survey points where sparrows have been detected. Sparrow 
surveys are based on a point-count survey method, which is a standard 
method for passerine birds. Surveys are conducted each year during the 
peak of sparrow breeding season. Details of the survey are described in 
Pimm et al. 2002. An array of survey points has been established across 
all potential sparrow habitats with survey points arranged on a grid. 
Because the survey area covers an expanse of area that does not contain 
roads or trails, observers are dropped off at survey points from a 
helicopter. The helicopter departs the area prior to the count 
initiating. An observer records all sparrows heard or seen at the point 
during a 7-minute period. The great majority of sparrow detections 
consist of territorial males. Following the completion of the count, 
the helicopter returns to transport the observer to the next survey 
point. Each survey point is visited once per season.
    Because survey points are arranged on a 0.6-mi (1-km) grid and 
sparrows may only be detected accurately within 656 ft (200 m) of a 
survey point (Pimm et al. 2002, p. 153), some areas between survey 
points remain unsurveyed. We used a 2,460-ft (750-m) radius around each 
sparrow occurrence to account for unsurveyed areas adjacent to or 
between the survey points where sparrows likely occurred. The 2,460-ft 
(750-m) radius distance is approximately half of the distance between 
diagonally adjacent survey points. In addition, this distance is 
slightly larger than the sum of the reliable sparrow detection distance 
from a point (200 m) plus the diameter of an average non-breeding 
season sparrow home range (465 m, assuming a circular home range based 
on home range sizes in Dean and Morrison 2001, p. 36). This distance 
consequently represents an estimate of the area of habitat that 
sparrows detected at a point are likely to use.
    We drew a boundary that encompassed the 750-m radius around sparrow 
locations but also took into account the particular habitat 
characteristics as determined through detailed inspection of satellite 
imagery, aerial photography, and habitat maps. Outlying sparrow 
occurrences that were recorded in only one year and were not adjacent 
to other recorded sparrow observations were excluded. Areas along the 
boundary that did not contain features essential for the sparrow (such 
as tree islands, cypress forest, and deep-water slough communities) 
were excluded from the unit. The resulting boundary of each unit 
encompassed the core areas of habitat that have been occupied by 
sparrows since 1981. This approach relies on the results of multiple 
years of surveys and consequently provides a robust assessment of 
sparrow habitat.
    We believe the method we have used to delineate critical habitat 
encapsulates the habitat that is important over time for all aspects of 
the sparrow's life history, accounting for the degree of natural 
variability in environmental and habitat conditions that occur within 
the Everglades.

Primary Constituent Elements

    In accordance with section 3(5)(A)(i) of the Act and regulations at 
50 CFR 424.12, in determining which areas to propose as critical 
habitat, we consider within areas occupied by the species at the time 
of listing those physical and biological features that are essential to 
the conservation of the species (PCEs), and that may require special 
management considerations and protection. These include, but are not 
limited to, space for individual and population growth and for normal 
behavior; food, water, air, light, minerals, or other nutritional or 
physiological requirements; cover or shelter; sites for breeding, 
reproduction, and rearing (or development) of offspring; and habitats 
that are protected from disturbance or are representative of the 
historic geographical and ecological distributions of a species.
    The following information provides the justification and background 
for the PCEs for the Cape Sable seaside sparrow as they are defined at 
the end of the Primary Constituent Elements section.

Space for Individual and Population Growth and Normal Behavior (Open 
Contiguous Habitat)

    Sparrow subpopulations require large patches of contiguous open 
habitat (approximately 4,000 ac/1,619 ha or larger). The minimum area 
required to support a population has not been specifically determined, 
but the smallest area that has remained occupied by Cape Sable seaside 
sparrows for an extended period is this size. Individual sparrows are 
area-sensitive and generally avoid the edges where other habitat types 
meet the marl prairies. They will only occupy small patches (less than 
100 ac; 40.5 ha) of marl prairie vegetation when the patches occur 
within large, expansive areas and are not close to forested boundaries 
(Dean and Morrison 2001, p. 62-63). Once sparrows establish a breeding 
territory, they exhibit high site fidelity, and each individual sparrow 
may only occupy a small area for the majority of its life. Because 
sparrows are generally sedentary and avoid forested areas, they are not 
likely to travel great distances to find mates or to find outlying 
patches of

[[Page 63987]]

suitable habitat. The occurrence of sparrows over time within each of 
the subpopulations shows a centrality in which sparrows most 
consistently occur and are most abundant near the center of the patch 
of habitat in which they occur.
    Within the marl prairies, individual trees or shrubs greater than 
4.9 ft (1.5 m) tall at a density greater than or equal to 2.5 per ac (1 
per ha), excluding tree islands composed of native tropical-Caribbean 
species occurring on an elevated substrate, will make the site 
unsuitable.
    As detailed in the background section, structure of habitat within 
the marl prairie (muhly grasses and little overstory) and areas of 
potential habitat are also important to sparrows because of the 
inherent variability in habitat conditions. While there is relatively 
little elevational variation within the Everglades, differences in 
elevation as small as 12 in (30 cm) can result in very different plant 
community and habitat characteristics. Single rainfall events in the 
region can deposit greater than 12 in (30 cm) of rain within a short 
period, and the variability in elevation and vegetation characteristics 
is critical to provide refugia for sparrows under these adverse 
conditions.

Diet

    While detailed information about the diet of sparrows is not known, 
invertebrates comprise the majority of their diet, though sparrows may 
also consume seeds when they are available (Werner 1975, p. 124; Post 
and Greenlaw 1994, p. 5). Howell (1932, p. 463) identified the contents 
of 15 sparrow stomachs and found remains primarily of insects and 
spiders, as well as amphipods, mollusks, and plant matter. Primary prey 
items that are fed to nestlings during the breeding season include 
grasshoppers (Orthoptera), moths and butterflies (Lepidoptera), 
dragonflies (Odonata), and other common large insects (Post and 
Greenlaw 1994, p. 5; Lockwood et al. 1997, p. 726). Adult sparrows 
probably consume mainly the same species during the nesting season. 
Sparrows may consume different proportions of different species over 
time and among sites, suggesting that they are dietary generalists 
(Pimm et al. 2002, p. 23). During the non-breeding season, preliminary 
information from evaluation of fecal collections suggests that a 
variety of small invertebrates, including weevils and small mollusks, 
are regularly consumed (Dean and Morrison 2001, p. 54). Evidence of 
seed consumption was only present in four percent of samples (Dean and 
Morrison 2001, p. 54). These non-breeding season samples may not be 
representative of the foods most frequently consumed during that season 
and may only represent a portion of the items ingested.
    While the sparrow appears to be a dietary generalist, an important 
characteristic of sparrow habitat is its ability to support a diverse 
array of insect fauna. In addition, these food items must be available 
to sparrows both during periods when there is dry ground and during 
extended periods of inundation. The specific foraging substrates used 
are unknown, but they probably vary throughout the year in response to 
hydrologic conditions.

Sites to Support Foraging, Nesting, and Sheltering

    Sparrows maintain territories that support all aspects of their 
life history (Werner and Woolfenden 1983, p. 67) and sparrows are 
completely reliant on the vegetation, like muhly grass, within their 
home ranges for foraging, nesting, and sheltering. Vegetation must also 
be sufficient to support them during extreme hydrologic conditions. 
Favorable vegetation characteristics are essential to the sparrow's 
survival and conservation.
    During the dry portion of the year (December to May), when water 
levels are near or below ground surface, vegetation must be 
sufficiently dense to provide cover from potential predators like 
raptors and small mammalian predators, as well as for concealing nests. 
Sparrows most commonly move across the ground's surface. During the dry 
portion of the breeding season (March to May), sparrows build nests 
above the ground but relatively low in the vegetation (6.7 to 7.1 
inches (17 to 18 cm) above the ground; Lockwood et al. 2001, p. 278).
    During the wet portion of the year (June to November), the majority 
of or the entire ground surface may be inundated for extended periods. 
During these periods, the vegetation within a sparrow's home range 
serves as the substrate for sparrows, and they travel over and through 
it. Vegetation must be sufficiently dense and tall such that it can 
support the weight of sparrows as they move through it. In addition, it 
must provide cover and escape refugia in the structure of the plants 
from predators. Vegetation must also be sufficiently dense to support 
nests above the water. During the wet portion of the sparrow breeding 
season (June to August), sparrows build their nests higher in the 
vegetation than during dry periods, an average of 8.3 in (21 cm) above 
the ground surface (Lockwood et al. 2001, p. 278). Even at the nest 
height, there must be sufficient height and density of vegetation to 
cover and conceal nests.
    Vegetation must provide sufficient diversity and structure to 
provide foraging opportunities for sparrows. The birds must be able to 
find and capture insect prey both during periods when the ground is dry 
and when the area is inundated. Seeds that are consumed during the wet 
season must be gleaned from standing vegetation since any seeds on the 
ground are covered by water and periphyton and are inaccessible to 
sparrows.

Hydrologic Regime

    Hydrologic conditions have significant effects on sparrows both 
directly and indirectly. First, depth of inundation within sparrow 
habitat is directly related to the sparrow's ability to move, forage, 
nest, and find shelter and cover from predators and harsh environmental 
conditions. At some extreme water levels, such as those that occurred 
within some areas of sparrow habitat in October 1995, when water levels 
were more than 2 ft. (0.6 m) above ground surface, even the majority of 
the vegetation in sparrow habitat is completely inundated, leaving 
sparrows with few refugia. Conditions such as these may result in 
significant impacts to sparrow survival, and if they occur during the 
breeding season, these water levels will cause flooding and loss of 
sparrow nests (Nott et al. 1998, p. 31; Pimm and Bass 2002, p. 416 ). 
Even more moderate water levels, around 6 in. (15 cm) above ground 
surface, may sufficiently inundate some habitat such that sparrows are 
incapable of finding shelter and moving around within limited areas. 
These water levels, when they occur during sparrow nesting season, 
result in increased rates of nest failure due to depredation (Lockwood 
et al. 1997, p. 724).
    The hydrologic regime also affects sparrows indirectly through its 
effects on the vegetation community. Persistent increases in 
hydroperiod may quickly result in changes in vegetation communities 
from marl prairies or mixed prairies to sawgrass-dominated communities 
resembling sawgrass marshes (Nott et al. 1998, p. 30). Average 
hydroperiods that extend beyond 210 days per year generally result in 
sawgrass marsh communities (Ross et al. 2006, p. 14).
    Conversely, areas that are subjected to short hydroperiods 
generally have higher fire frequency than longer-hydroperiod areas 
(Lockwood et al. 2003, p. 464; Ross et al. 2006, p. 43), and are 
readily invaded by woody

[[Page 63988]]

shrubs and trees (Werner 1975, p. 204; Davis et al. 2005, pp. 824-825). 
Both an increased incidence of fire and an increased density and 
occurrence of shrubs detract from the suitability of an area as sparrow 
habitat.
    The plant species composition and density in the Everglades are 
largely influenced by hydroperiods. Hydroperiods that range from 60 to 
270 days support the full variety of vegetation conditions that are 
generally suitable for sparrows (Ross et al. 2006, p. 14), though the 
vegetation composition and structure may vary significantly within this 
range.

Soils

    The soils that underlie sparrow habitat are composed almost 
entirely of calcitic marl. These soils are not rich in organic matter 
and are formed when periphyton mats precipitate calcite (Davis et al. 
2005, p. 825). In areas where hydroperiods are short, periphyton mats 
do not form, and marl soil accretion is slow, resulting in shallow 
soils (sometimes less than 0.8 in. (2 cm)) that do not support dense 
plant growth. The vegetation community within the marl prairies is 
uniquely associated with marl soils (Davis et al. 2005, p. 825) and 
does not occur on other soil series, though individual plant species 
that occur in marl prairies may occur in other conditions.
    The short hydroperiods within these marl prairie communities also 
result in oxidation of organic matter or consumption of organic matter 
during fires. Sawgrass marsh plant communities may become established 
in areas with longer hydroperiods that usually contain organic peat 
soils that dry less frequently than marl prairies (Ross et al. 2006, p. 
10; Ogden 2005, p. 813). Marl soils, and particularly deeper marl soils 
formed through continuous deposition of calcitic sediments from 
periphyton, support the density and diversity of plant species upon 
which sparrows rely. While similar vegetation may occasionally occur 
over peat soils with a surficial periphyton layer, these areas may not 
support sparrow habitat in the long term because they may tend to 
succeed toward sawgrass marsh vegetation under long hydroperiods, or 
they may be significantly altered when fires consume underlying peats 
during dry conditions.

Primary Constituent Elements for the Cape Sable Seaside Sparrow

    Based on the above discussion of the life history, biology, and 
ecology of the species and the requirements of the habitat to sustain 
the essential life history functions of the species, we have determined 
that the Cape Sable seaside sparrow's PCEs consist of:
    (1) Calcitic marl soils characteristic of the short-hydroperiod 
freshwater marl prairies of the southern Everglades.
    (2) Herbaceous vegetation that includes greater than 15 percent 
combined cover of live and standing dead vegetation of one or more of 
the following species (when measured across an area of greater than 100 
feet 2 per 30.5 meters 2): Muhly grass 
(Muhlenbergia filipes), Florida little bluestem (Schizachyrium 
rhizomatum), black-topped sedge (Schoenus nigricans), and cordgrass 
(Spartina bakeri).
    (3) Contiguous open habitat. Sparrow subpopulations require large, 
expansive, contiguous habitat patches with few or sparse woody shrubs 
or trees.
    (4) Hydrologic regime such that the