Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition to Delist the Pacific Coast Population of the Western Snowy Plover, 20607-20624 [06-3792]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 71, Number 77 (Friday, April 21, 2006)]
[Proposed Rules]
[Pages 20607-20624]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-3792]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17


Endangered and Threatened Wildlife and Plants; 12-Month Finding 
on a Petition to Delist the Pacific Coast Population of the Western 
Snowy Plover

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 12-month petition finding.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
12-month finding on a petition to remove the Pacific coast population 
of the western snowy plover (Charadrius alexandrinus nivosus) from the 
Federal List of Threatened and Endangered Wildlife pursuant to the 
Endangered Species Act of 1973, as amended. After reviewing the best 
scientific and commercial information available, we find that the 
petitioned action is not warranted. We ask the public to submit to us 
any new information that becomes available concerning the status of, or 
threats to, the species. This information will help us monitor and 
encourage the conservation of this species.

DATES: The finding announced in this document was made on April 21, 
2006.

ADDRESSES: Data, information, comments, or questions concerning this 
finding may be sent to the Field Supervisor (Attn: WSP-DELIST), Arcata 
Fish and Wildlife Office, U.S. Fish and Wildlife Service, 1655 Heindon 
Road, Arcata, California 95521-5582 (fax: 707-822-8411). The petition 
and supporting information are available for public inspection, by 
appointment, during normal business hours, at the above address.

FOR FURTHER INFORMATION CONTACT: Jim Watkins, Fish and Wildlife 
Biologist, in Arcata (telephone: 707-822-7201).

SUPPLEMENTARY INFORMATION:

Background

    Section 4(b)(3)(A) of the Endangered Species Act (Act) of 1973, as 
amended (16 U.S.C. 1531 et seq.) requires that we make a finding on 
whether a petition to list, delist, or reclassify a species presents 
substantial information to indicate the petitioned action may be 
warranted. Section 4(b)(3)(B) of the Act requires that within 12 months 
after receiving a petition to revise the List of Threatened and 
Endangered Wildlife and Plants that contains substantial information 
indicating that the petitioned action may be warranted, the Secretary 
shall make one of the following findings: (a) The petitioned action is 
not warranted, (b) the petitioned action is warranted, or (c) the 
petitioned action is warranted but precluded by higher priority 
workload. Such 12-month findings are to be published promptly in the 
Federal Register.

Previous Federal Action

    The Pacific coast population of the western snowy plover 
(Charadrius alexandrinus nivosus) (Pacific Coast WSP) was listed as 
threatened on March 5, 1993 (Service 1993 (58 FR 12864)), prior to 
publication of our 1996 distinct population segment (DPS) policy 
(Service and NMFS 1996a (61 FR 4722; February 7, 1996)). At the time of 
listing, the primary threat to the plover was the loss and degradation 
of habitat from human activities. Critical habitat for the Pacific 
Coast WSP was designated on September 9, 2005 (70 FR 56969).
    On July 29, 2002, we received a petition from the Surf-Ocean Beach 
Commission of Lompoc, California, to delist the Pacific Coast WSP 
pursuant to the Act. We also received a similar petition dated May 30, 
2003, from the City of Morro Bay, California. As explained in our 1996 
Petition Management Guidance (Service and NMFS 1996b), subsequent 
petitions are treated separately only when they are greater in scope or 
broaden the area of review of the first petition. The City of Morro Bay 
petition repeats the same information provided in the Surf-Ocean Beach 
Commission petition and was therefore treated as a comment on the first 
petition received. On March 22, 2004 (69 FR 13326), we announced an 
initial (90-day) finding that the petition presented substantial 
information to indicate the petitioned action may be warranted, and we 
initiated a status review under sections 4(b)(3)(A) and 4(c)(2)(A) of 
the Act. We have now completed the status review on the species using 
the best available scientific and commercial information, and have 
reached a determination regarding the petitioned action. This status 
review also fulfills the requirements of 4(c)(2).

Species Information

    Snowy plovers are small shorebirds, about 16 centimeters (6 inches) 
long, with pale brown upperparts, buff-colored bellies, and darker 
patches on their shoulders and heads. Their dark gray to black legs are 
a useful distinguishing feature when comparing to other plover species 
(Page et al. 1995a). Two subspecies of snowy plover

[[Page 20608]]

recognized by the American Ornithological Union (AOU 1957), nest in 
North America: The western snowy plover and the Cuban snowy plover 
(Charadrius alexandrinus tenuirostis).

Biology and Distribution

    The breeding range of the western snowy plover includes sites in 
California, Oregon, Washington, Nevada, Utah, Arizona, Colorado, New 
Mexico, Kansas, Oklahoma, Texas, and Baja California, central and 
northeastern Mexico, as well as irregularly visited sites in 
Saskatchewan, Canada; and Wyoming and Montana (Page et al. 1995a) (see 
Figure 1). In 1993, we listed and defined the Pacific Coast WSP as 
those western snowy plovers ``that nest adjacent to or near tidal 
waters'' of the Pacific Ocean (Service 1993 (58 FR 12864)). In this 
finding, we refer generally to plovers nesting at locations other than 
on the Pacific coast as ``interior'' populations, even though this term 
includes populations nesting on the Gulf coast. We also refer to 
interior nesting populations according to whether they nest east or 
west of the Rocky Mountains, on the Gulf Coast, or in central Mexico.

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[GRAPHIC] [TIFF OMITTED] TP21AP06.000

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    The second North American subspecies, the Cuban snowy plover, nests 
along the Gulf coast from Louisiana to western Florida and south 
through the Caribbean (American Ornithological Union (AOU) 1957; 
Service 1993 (58 FR 12864); Page et al. 1995a). The subspecific status 
of populations breeding east of the Rocky Mountains, now considered to 
belong to the subspecies C. a. nivosus, has been questioned. Some 
consider these populations to belong more appropriately to the 
subspecies C. a. tenuirostris (Warriner et al. 1986). Others consider 
the subspecies C. a. tenuirostris to be a paler version of the western 
snowy plover rather than a separate subspecies (Page et al. 1995a). In 
this status review, we rely on the current American Ornithological 
Union taxonomic classification that considers C. a. nivosus to be a 
valid subspecies (AOU 1957).
    Some plovers nesting on the Pacific coast migrate north or south to 
other Pacific coastal wintering sites, while others stay at their 
breeding sites year round. Birds nesting in the interior, west of the 
Rocky Mountains (the western interior population) winter in coastal 
California and Baja California, Mexico, and often commingle with the 
Pacific Coast WSP. However, some individuals from the southern 
California interior do not migrate (Page et al. 1995a). Plovers from 
the interior east of the Rockies are migratory, probably wintering on 
the Gulf Coast, except for small numbers of year-round residents in 
Texas, Arizona, and New Mexico. Plovers nesting on the Gulf coast may 
sometimes winter at other Gulf coast locations, while those nesting in 
central Mexico are likely year-round residents (Page et al. 1995a).
    The timing of the nesting season varies with location, but in 
coastal California it tends to run from March through September (Page 
et al. 1995a). Breeding locations tend to be sandy areas close to 
water, including beaches, salt pans, alkaline playas, and gravel bars 
on the tidally influenced portion of coastal rivers. Clutches, which 
most commonly consist of three eggs, are laid in shallow scrapes or 
depressions in the sand. Snowy plovers generally form monogamous pair 
bonds and share incubation duties, but western snowy plover females 
typically desert the brood shortly after hatching, and may renest with 
a new male if time remains in the season to do so. Males typically care 
for the young until they fledge, which takes about a month, and may 
then renest with a new partner if sufficient time remains in the season 
(Stenzel et al. 1994). This results in a serially polygamous breeding 
system in which males may double clutch and females may triple clutch 
during a single season (Page et al. 1995a).

Population Status

    The current known breeding range of the Pacific Coast WSP extends 
from Damon Point, Washington, to Bahia Magdelena, Baja California, 
Mexico. Observed estimates for the Pacific Coast WSP, rangewide, are 
approximately 3,700 individuals; within that total, the observed 
estimate of the U.S. population of the Pacific Coast WSP is 
approximately 1,800 adults (see Table 1) (L. Stenzel, in litt. 2004a; 
G. Page, in litt. 2005b; L. Kelly, in litt. 2006; M. Jensen, in litt. 
2006). Current population estimates are developed by multiplying the 
number of adult plovers observed during breeding window surveys (Table 
1 Observed Estimate) by a correction factor of 1.3, which adjusts the 
observed number to that of a known population (Table 1 Current 
Population Estimate). Multiplying the observed estimates by the 
correction factor, the current population estimate for the United 
States portion of the Pacific Coast WSP is approximately 2,300 (see 
Table 1), based on the 2005 breeding window survey (Stenzel, in litt. 
2004b; Page, in litt. 2005b; Jensen, in litt. 2006; Kelly, in litt. 
2006), and the current population estimate for the Pacific Coast WSP 
rangewide is approximately 4,800.

     Table 1.--Observed and Estimated Numbers of Adult Western Snowy Plovers in the United States and Mexico
                                  [Adapted and updated from Page et al. 1995a]
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                                            Observed                          Observed       Current population
           Location               Year       number          Source         estimate \1\        estimate \2\
----------------------------------------------------------------------------------------------------------------
U.S. Pacific Coast...........        2005  ..........  A                  1,795             2,334.
Washington...................        2005          15  I                  ................  ....................
Oregon.......................        2005         100  H                  ................  ....................
California...................        2005       1,680  A                  ................  ....................
Mexico, West Coast of Baja      1991-1992       1,344  B, C               At least 1,900    At least 2,470.
 California.
----------------------------------------------------------------------------------------------------------------
Pacific Coast WSP Estimated Total                                         3,695             4,804.
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Interior U.S., west of Rocky
 Mtns.:
    All States except Utah...        1988  ..........  C                  6,100             7,930.
    Nevada...................        1988         691  C                  ................  ....................
    Oregon...................        1988         552  C                  ................  ....................
California:
    Great Basin..............        1988       1,213  C                  ................  ....................
    San Joaquin Valley.......        1988         241  C                  ................  ....................
    S. California deserts....        1988         291  C                  ................  ....................
Utah.........................        1992       1,501  D                  4,189             5,445.
Great Plains:
    Colorado.................     1986-92  ..........  C, G               Up to 150         Up to 195.
    Kansas...................     1986-92  ..........  C, G               Up to 356         Up to 463.
    Oklahoma.................     1986-92  ..........  C, G               2,007             2,609.
    Texas....................     1986-92  ..........  C, G               500               650.
    New Mexico...............     1986-92  ..........  C, G               Up to 500         Up to 650.
Gulf Coast:
    Texas....................        2004  ..........  E                  1,000             1,300.
    NE Mexico................        1992  ..........  G                  Up to 34          Up to 44.
Interior Mexico..............        1994  ..........  F                  At least 35       At least 46.

[[Page 20611]]

 
    Presa Acecatecana........  ..........          12  .................  ................  ....................
    Salinas de Hidalgo.......  ..........          16  .................  ................  ....................
    Jalisco (near Atoyac)....  ..........           6  .................  ................  ....................
    Lago Texcoco.............  ..........           1  .................  ................  ....................
----------------------------------------------------------------------------------------------------------------
Estimated Total for Interior and Gulf Coast Breeding WSP                  14,871            19,332.
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Estimated Grand Total for the Subspecies                                  18,566            24,136.
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\1\ The Observed Estimate (Obs. Est.) is approximated for the Mexico portion of the range based upon the
  research conducted by Page et al. (1995a).
\2\ The 2005 Current Population Est. equals the Obs. Est. multiplied by a correction factor of 1.3. The Obs.
  Est. often under counts the actual number of birds. Research by the Point Reyes Bird Observatory shows a
  correction factor is needed to give a more accurate population count (Stenzel in litt. 2004a).
Sources: A = G. Page in litt. 2005; B = E. Palacios et al. 1994; C = G. Page et al. 1995a; D = P. Paton in litt.
  2004; E = Zdravkovic 2004; F = Howell and Webb 1994; G = Gorman and Haig 2002; H = L. Kelly in litt. 2006; I =
  M. Jensen in litt. 2006.

    Recent census data for the Baja California, Mexico population of 
the Pacific Coast WSP do not exist; however, we use the observed 
estimate of 1,900 adults as provided in Page et al. (1995a), as that is 
the best available information. The population is sparse in Washington, 
Oregon, and northern California. Historical records indicate that 
nesting plovers were once more widely distributed and abundant in 
coastal Washington, Oregon, and California than at present (Page et al. 
1995a). At about the time the species was listed under the Act, 
approximately 2,000 western snowy plovers bred along the United States 
Pacific Coast (Page et al. 1995a) and approximately 1,900 bred on the 
west coast of Baja California, Mexico (Palacios et al. 1994). The 
largest number of breeding birds occurred from south San Francisco Bay 
to southern Baja California (Page and Stenzel 1981; Palacios et al. 
1994).
    Washington--Occupancy of Sites: In Washington, plovers formerly 
nested at five coastal sites (Washington Department of Fish and 
Wildlife 1995). Three of these remain currently active, indicating a 40 
percent decline in the number of Washington breeding areas. Occupancy 
at sites in Washington has declined for several reasons, including site 
degradation due to beach erosion (e.g., Westport Spit, Leadbetter 
Point, Gunpowder Sands Island). Subsequent to the 1993 listing, habitat 
conditions have improved or expanded at other sites (e.g., Midway 
Beach).
    Washington--Number of Pacific Coast WSP: The number of birds in 
Washington, however, appear to be stable to increasing since the early 
1990s, based on consistent, intensive, repeatable counts of adults 
during the breeding season. Breeding season surveys indicate a general 
increase in the plover breeding population since 1995 (Washington Dept. 
of Fish and Wildlife, in litt. 2003). Population numbers range from a 
low of 19 adults in 1994, to 68 in 2003. In recent years, sand has 
built up at Midway Beach creating high quality habitat, and nesting was 
documented in 1998 (Richardson et al. 2000). Uniquely banded plovers 
from natal locations along the Oregon and California coasts have bred 
in Washington coastal sites, adding to the overall breeding population 
within the State. We attribute the increases to improved coastal 
habitat at some locations, and intensive management in Oregon and 
California.
    Oregon--Occupancy of Sites: In Oregon, plovers historically nested 
at 29 coastal locations. Our 1993 listing decision was based, in part, 
on the loss of 23 of those locations (Service 1993 (58 FR 12864)). 
However, in 2004, the number of breeding sites had increased to 10 due 
to the reoccupation of 4 historic sites (D. Lauten, in litt. 2004). As 
a result, 65 percent (19 of 29) of the historic nesting locations have 
been lost; improved from 79 percent at the time of listing.
    Oregon--Number of Pacific Coast WSP: Annual surveys of adult and 
juvenile plovers in coastal Oregon began in 1978, with intensive 
monitoring beginning in 1993. Survey data shows a general decline in 
breeding adults throughout coastal Oregon until 1994, at which time the 
trend reversed to an increase in breeding adults. Although the overall 
breeding population trend is still down from historical numbers, the 
period from 1994 to present has shown a slight increase (J. Baldwin, in 
litt. 2004). Plovers from California have been observed nesting in 
coastal Oregon, contributing to the State's breeding population, 
estimated at 110 birds in 2003 (Oregon Department of Parks and 
Recreation 2003). Eighty-three plovers were observed during breeding 
surveys in 2004, and 100 were counted during the 2005 breeding season 
(Lauten et al. 2006). We attribute the increase directly to protections 
and resultant management from the 1993 Federal listing. Management 
measures benefiting plovers include the use of exclosures to reduce 
nest predation, restoration of breeding habitat by removing European 
beachgrass (Ammophila arenaria), increased use of signs and symbolic 
fencing (temporary post and cable) around breeding sites, intensified 
public information, and enhanced law enforcement.
    California--Occupancy of Sites: Eight geographic areas in 
California support over three-quarters of the Statewide coastal 
breeding population (Page et al. 1991). By the late 1970s, nesting 
plovers in California were absent from 33 of 53 of the breeding 
locations having breeding records prior to 1970 (Page and Stenzel 
1981). Stenzel (in litt. 2004b) has subsequently identified an 
additional 11 locations that have lost nesting plovers. An estimated 
1,566 adult plovers were seen during initial Statewide coastal surveys 
by Point Reyes Bird Observatory (PRBO) during the 1977 to 1980 breeding 
seasons (Page and Stenzel 1981). The surveys indicated that by 1980, 
plovers had been extirpated or severely reduced in breeding 
distribution throughout substantial portions of their coastal southern 
California breeding range, especially in San Diego, Orange, and Los 
Angeles Counties. With the exception of some beach segments along

[[Page 20612]]

Monterey Bay in Monterey County, breeding plovers were absent or 
severely reduced at other historic breeding sites along the southern 
and central California coast. A preliminary analysis of current 
breeding sites identifies 10 new, low-density breeding locations (L. 
Stenzel, in litt. 2004b). However, analysis also shows that at least 44 
of the historic sites, many of which were known to be high-density 
sites, have not had any recent nesting activity (L. Stenzel, in litt. 
2004a; 2004b).
    California--Number of Pacific Coast WSP: In addition to losses of 
breeding locations, or lack of activity at breeding locations, 
Statewide beach surveys conducted by PRBO during 1989 and 1991 also 
indicated a decline in numbers of breeding plovers. Along the 
California coast, including the Channel Islands, plover numbers 
declined by almost 5 percent, and the estimated decline at San 
Francisco Bay was about 40 percent (A. Powell, pers. comm. 1998; Point 
Reyes Bird Observatory, unpublished data). More recent surveys during 
the breeding seasons of 2000, 2002, 2003, 2004, and 2005, were 
accomplished through a collaboration of researchers studying plovers in 
coastal California. Results are provided in Table 2, below.

                       Table 2.--Total Number of Adult Snowy Plovers During Breeding Season Window Surveys of the California Coast
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                                                           1977-1980
                          Year                                \1\      1989 \2\    1991 \3\    2000 \3\    2002 \3\    2003 \3\    2004 \3\    2005 \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total...................................................      1,566       1,386       1,371         976       1,387       1,444       1,904      1,680
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Page and Stenzel 1981--Surveys were conducted in multiple years; \2\ Page et al. 1991; \3\ L. Stenzel, in litt. 2004a; \4\ Page in litt. 2005.

    In 2000, there were 976 breeding adult plovers observed in coastal 
California. Surveyors observed 1,387 and 1,444 adult plovers during 
similar breeding season surveys conducted in 2002 and 2003, 
respectively. Statewide breeding season window surveys for California 
demonstrate an increase in observed breeders from 2001 through 2005, 
although there is still an overall decline when compared to historic 
breeding population numbers (J. Baldwin, in litt. 2004; K. Lafferty, in 
litt. 2002).
    The increase in the number of adult plovers observed during 
breeding season window surveys in the southern part of California is 
related, at least in part, to protections and associated management 
provided to the federally endangered California least tern (Sterna 
antillarum browni) (Persons and Applegate 1996). Predator management, 
habitat restoration, leash laws, controlled recreational vehicle use, 
symbolic fencing, and other measures have contributed to the Statewide 
increase in breeding Pacific Coast WSP and also provided benefits to 
interior plovers wintering on the coast.
    Baja California, Mexico--Occupancy of Sites and Number of Pacific 
Coast WSP: Along the Pacific coast of Baja California, Mexico, most 
plover nesting areas are associated with the largest wetlands. A survey 
of breeding western snowy plovers along the Pacific coast of Baja 
California between 1991 and 1992 found 1,344 adults, mostly at four 
coastal wetland complexes: Bahia San Quintin, Lagunas Ojo de Liebre and 
Guerrero Negro, Laguna San Ignacio, and Bahia Magdalena (Palacios et 
al. 1994). Based on detection ratios established for surveys on the 
United States Pacific coast, this indicated a coastal Baja population 
of at least 1,900 adults (Palacios et al. 1994; Page et al. 1995a). We 
have no information of any more recent estimates (E. Palacios, in litt. 
2004).

Discussion of the Petition

    The petition asserts that the Pacific Coast WSP does not meet the 
Act's definition of a threatened species as its population is in flux 
rather than decline. The petition offers a table and a graph to support 
this assertion: The graph in section 5.1.2 of the petition provides 
breeding population counts for Vandenberg Air Force Base (VAFB) for 
1978 through 2001, and the table in section 5.1 (included as part of 
Table 2 above) provides breeding population census counts for the 
California coast during 6 years from 1980 to 2000. The graph shows VAFB 
breeding population fluctuating in size from more than 100 to about 20 
between 1978 and 2001.
    The petition states that the VAFB data reflect dramatic 
fluctuations that can occur within the plover population. Vandenberg 
has two sections of beach that support plover breeding known as North 
Beach and South Beach. The graph presented within the petition 
(subsection 5.1.2) shows that Vandenberg's plover population has 
fluctuated dramatically, with an overall increase from 119 birds in 
1978 to 121 birds in 2001 (Surf Ocean Beach Commission 2002). However, 
the petition does not provide the sources for the data in the graph. We 
believe the data in the petition's graph from 1993 to 2001 are from 
annual plover monitoring reports that VAFB started in 1993 (e.g., 
Persons 1994; Hickey and Page 2001) because we know of no other source 
from which the information could have come.
    It appears that the 1978 data in the petition's graph are from Page 
and Stenzel (1981), but it is not clear upon what the intermittent 
counts presented in the graph between 1978 and 1993 are based. This 
graph shows a population increase from 193 to 239 breeding adults over 
the years 1993 to 1997, a decrease to 132 and then 78 adults in 1998 
and 1999 following severe storms and an oil spill in the winter of 1997 
through 1998, and then a slow increase up to 122 adults in 2001. The 
VAFB monitoring reports also note generally increasing efforts to 
exclude human interference with nesting during these years. Based on 
these data alone, it appears that plover breeding numbers can be 
seriously affected by random natural events such as heavy storms, but 
this does not support the petition's conclusion that the plover 
population is in flux rather than decline. The 1978 data, which 
petitioners offer as evidence of an overall increase of 119 to 121 
birds, was itself collected after heavy winter storms. These storms 
were so severe that only 7.1 mi (11.5 km) of beach were available for 
nesting (Page and Stenzel 1981; L. Stenzel, pers. comm. 2003); in 
contrast, in 2001, 12.5 linear miles (mi) [20.1 linear kilometers (km)] 
of beach were available for nesting (Hickey and Page 2001). The 1978 
numbers would therefore likely have been depressed from historic 
levels, and would constitute poor support for the petition's 
conclusions regarding overall population trends. More importantly, we 
do not consider census data from VAFB alone to reasonably support 
conclusions concerning the entire Pacific coast population. Pacific 
Coast WSP do occasionally nest or renest at other coastal locations 
(Stenzel et al. 1994; Page et al. 1995a), so fluctuations in the VAFB 
breeding population could either be caused or moderated by

[[Page 20613]]

immigration to and emigration from other beaches.
    The table in section 5.1 of the petition provides census data for 
the California coast and serves as a better indication of population 
trends for the Pacific Coast WSP, because ``the California coast 
population represents at least 90 percent of the listed Pacific coast 
population in the United States'' (D. Noda, in litt. 2001) (see table 
1). Yet, the data presented in this petition table show a steady 
decrease in population from 1980 to 2000 except for a particularly high 
count in 1997 and a somewhat low count in 1995. The 1997 and 1995 
surveys were both conducted differently than those for other years and 
are therefore not directly comparable to other years. The 1995 census 
did not include counts from several important breeding sites such as 
South San Francisco Bay (P. Nieto, SRS Technologies, in litt. 2002; L. 
Stenzel in litt. 2004a; G. Page, pers comm. 2003). The 1997 population 
estimate is based on intensive monitoring information for some areas 
combined with ``corrected'' window survey data from previous years for 
other areas (Nur et al. 1999; G. Page, pers. comm. 2003). All other 
population estimates in the petition's table in section 5.1 are totals 
of window survey counts from the known breeding sites.
    We developed Table 2 (above) to show California coastal population 
estimates based on the observed number of adult plovers during breeding 
season window surveys. Table 2 consists of the population counts 
reported in the petition's table for years other than 1995 and 1997, 
along with population counts from 2002 through 2005 which we added to 
the Table.
    The increase first observed in 2002 is encouraging, and we 
attribute the population increases to the implementation of 
conservation strategies by our recovery implementation stakeholders, 
such as California State Parks, who have engaged in habitat restoration 
and the use of extensive symbolic fencing. It is also important to note 
that the population level documented by Page and Stenzel (1981), was 
likely depressed by severe storms and resulting beach erosion during 
the winter of 1977 through 1978 (Page and Stenzel 1981). Counts 
conducted at VAFB from 1998 through 2000 showed a drop in adult plover 
numbers from 238 to 132 following similarly severe storms during the 
winter of 1997/1998 (Applegate and Schultz 1999; Applegate and Schultz 
2000). Although the survey conducted in 1977 through 1980 provided 
fairly high population estimates, Page and Stenzel (1981) noted: 
``Numbers have definitely declined on the coast; the species was not 
found breeding in 33 of the 53 locations with breeding records prior to 
1970. Of the 33 areas, 28 are not likely to have regular breeding 
populations again because the habitat has been destroyed or human use 
of the area is too great.'' The petition interprets such conclusions as 
speculative since they were not based on census data and do not show 
how often particular breeding sites were used. While we agree that any 
precise population estimates based on such data would be speculative, 
we believe the indications of lost habitat provided by Page and Stenzel 
(1981) are well supported and reasonably lead to the conclusion that 
historic population levels were higher than those documented in the 
1977 to 1980 census. We therefore consider the available data on the 
coastal California population to provide more support for the 
contention that the Pacific Coast WSP has declined from historical 
levels.
    The listing decision was also based on the loss of 33 California 
breeding sites. An additional 11 sites have been subsequently 
identified as having also lost nesting plovers since the original work 
was completed and reported in the listing decision (L. Stenzel, in 
litt. 2004b). Consequently, the loss of 44 of 53 breeding sites in 
California represents an 83 percent reduction in historical nest 
locations. Some of those sites in southern California were especially 
significant. Places like Los Angeles County, where 25 miles of former 
breeding habitat were lost, may have supported up to 600 pairs (1200 
breeding birds) of plovers. The estimate is extrapolated from an egg 
collector's 1903 record of 50 pairs along a 2 mile section of Manhattan 
Beach (L. Stenzel, in litt. 2004b). At the time of the 1993 listing, 
Oregon had lost 79 percent (23 of 29) of its historic nesting sites, 
and Washington had lost 40 percent of its nesting locations (2 of 5) 
(Service 1993 (58 FR 12864)). Additionally, the remaining habitat has 
been degraded by the colonization of nonnative European beach grass by 
occupying nesting substrate and changing from the open structure that 
plovers prefer, increased number of predators, and increased human use. 
Addressing the above three factors through effective management range-
wide and the reestablishment of 4 former breeding sites in Oregon (D. 
Lauten, in litt. 2004) have bolstered plover populations since listing 
(G. Page, in litt. 2004a).
    The petition also cites a recent Pacific Coast WSP viability 
analysis that indicates the population would likely remain above an 
``extinction threshold'' of 50 individuals for at least 100 years under 
the 1999 status quo (Nur et al. 1999). However, the petition did not 
note that the ``status quo'' scenario (Scenario 1) assumed that 
existing protections and management actions under the Act would 
continue and projected a significant downward trend in population over 
the next 100 years in the absence of additional efforts. Under a ``no 
management'' scenario (Scenario 12), the analysis found a 51 percent 
probability of reaching an extinction threshold after 100 years. The 
analysis did not consider a scenario involving the complete removal of 
protections under the Act. We therefore do not consider the petition's 
statement that the Pacific Coast WSP population is healthy but in flux 
to be well supported by available data, especially if protections under 
the Act are removed.

Distinct Population Segment

    In a 12-month finding, we must determine if: (1) The petitioned 
action is warranted; (2) the petitioned action is not warranted; or (3) 
the petitioned action is warranted but precluded by other higher 
priority activities. Under the Act, a species is defined as including 
any subspecies and any distinct population segment of a vertebrate 
species (16 U.S.C. 1532). To implement the measures prescribed by the 
Act and its Congressional guidance, we and the National Marine 
Fisheries Service (National Oceanic and Atmospheric Administration-
Fisheries), developed a joint policy that addresses the recognition of 
DPSs of vertebrate species for potential listing actions (Service and 
NMFS 1996a (61 FR 4722)). The policy allows for a more refined 
application of the Act that better reflects the biological needs of the 
taxon being considered, and avoids the inclusion of entities that do 
not require its protective measures. As noted above, in 1993, we listed 
the Pacific Coast population of the WSP as threatened. As this was 
prior to our 1996 DPS policy, a first step in this status review 
process is to review the available information to assess whether the 
Pacific Coast WSP 1993 listing determination is consistent with the 
1996 DPS policy.
    The DPS policy specifies that we are to use three elements to 
assess whether a population segment under consideration for listing may 
be recognized as a DPS: (1) The population segment's discreteness from 
the remainder of the species to which it belongs; and (2) the 
significance of the population segment to the species to which it 
belongs; and (3) the population segment's conservation status in 
relation to the ESA's standard for listing (61 FR

[[Page 20614]]

4722, 4725). If we determine that a population segment meets the 
discreteness and significance standards, then the level of threat to 
that population segment is evaluated based on the five listing factors 
established by section 4(a) of the Act to determine whether listing the 
DPS as either threatened or endangered is warranted. The DPS policy 
also states: ``Listing, delisting, or reclassifying distinct vertebrate 
population segments may allow the Services to protect and conserve 
species and the ecosystems upon which they depend before large-scale 
decline occurs that would necessitate listing a species or subspecies 
throughout its entire range. This may allow protection and recovery of 
declining organisms in a more timely and less costly manner, and on a 
smaller scale than the more costly and extensive efforts that might be 
needed to recover an entire species or subspecies'' (61 FR 4722, 4725). 
Below, we address under our DPS policy the population segment of the 
WSP currently listed as a DPS that occurs within 50 miles of the 
Pacific coast in Oregon, Washington, California, and Mexico.

Discreteness

    The DPS policy states that a vertebrate population segment may be 
considered discrete if it satisfies either of the following two 
conditions:
    1. It is markedly separated from other populations of the same 
taxon as a consequence of physical, physiological, ecological, or 
behavioral factors. Quantitative measures of genetic or morphological 
discontinuity may provide evidence of this separation; or
    2. It is delimited by international governmental boundaries within 
which differences in control of exploitation, management of habitat, 
conservation status, or regulatory mechanisms exist that are 
significant in light of section 4(a)(1)(D) of the Act.
    The following discussion addresses only the first condition, since 
the Pacific Coast WSP DPS includes plovers within Baja California, 
Mexico and is not delimited by an international boundary.
    The 1993 listing rule stated that the Pacific Coast WSP is 
``genetically isolated'' from the interior breeding populations (58 FR 
12864). We based this conclusion on banding and monitoring data, not 
genetic data. At the time of listing, we assumed the reproductive 
separation indicated by the banding data, over time, could lead to 
genetic differentiation. Genetic data for the western snowy plover was 
not available in 1993.
    In this status review process, we examine the best information now 
available, which includes banding, monitoring, and genetic information, 
and assess the petition's additional points on discreteness, to 
determine if the 1993 listing determination was consistent with the 
1996 DPS policy. Western snowy plovers from populations in the eastern 
interior (east of the Rockies), the Gulf Coast, and the Mexican 
interior are not likely to interact with the Pacific Coast WSP, and are 
not known to visit the Pacific coast (Page et al. 1995a). We thus focus 
our discreteness analysis on the Western snowy plovers from populations 
in the western interior (west of the Rockies), and the Pacific Coast 
WSP.

Banding and Monitoring Information

    Banding and monitoring studies are useful methods for evaluating 
the discreteness of two populations provided that the banding effort 
adequately samples each population, and the monitoring effort is 
adequate to provide reasonable probabilities of detecting banded 
individuals (J. Plissner, in litt. 2005). Several banding and 
monitoring studies have been conducted that address the Pacific Coast 
WSP (Spear 1979; Stenzel and Peaslee 1979; Henderson and Page 1979; 
Widrig 1980; Page and Stenzel 1981; Page et al. 1983; Wilson-Jacobs and 
Meslow 1984; Warriner et al. 1986; Herman et al. 1988; G. Page, in 
litt. 1989; Page and Bruce 1989; Stern et al. 1990a, 1990b, 1991a, 
1991b; Page et al. 1991; ODFW 1994; Palacios et al. 1994; Paton 1994; 
Persons 1994, 1995; Stenzel et al. 1994; Page et al. 1995b; G. Page et 
al., Point Reyes Bird Observatory (PRBO), in litt. 2002; Powell et al. 
2002; C. Sandoval, in litt. 2002; G. Page, PRBO, in litt. 2004b; G. 
Page, PRBO, in litt. 2005). Some of these studies were not specifically 
designed for the purpose of evaluating the discreteness of the Pacific 
Coast WSP, but nonetheless provide useful information for this 
analysis.
    In this finding, we rely primarily on the banding and resighting 
efforts conducted during the period of 1984 through 1993, as this is 
the period when banding efforts were underway at several areas on the 
Pacific coast and in the western interior, and nest monitoring studies 
and breeding season surveys were underway at many locations when banded 
birds could be detected. Interior populations have not been banded 
since 1993 (L. Stenzel, in litt. 2005). From 1984 through 1993, a total 
of 4,170 plover chicks and breeding adults were banded at nine sites on 
the Pacific coast (3,077 banded birds), and at four western interior 
locations (1,093 banded birds) (G. Page, in litt. 2004b). The coastal 
locations included sites in both Oregon and central California, while 
the western interior locations included sites in Utah, Oregon, and 
California.
    Subsequent nest monitoring and breeding season surveys conducted in 
the Pacific coast and western interior breeding zones from 1985 through 
1995 provided an opportunity for resightings of banded birds. During 
that time, a total of 22 U.S. coastal surveys; 1 coastal Baja 
California, Mexico survey; and 4 western interior surveys were 
conducted, many of which were repeated over several years (Palacios et 
al. 1994; G. Page, in litt. 2004b). Collectively, these surveys covered 
essentially the entire extent of U.S. coastal breeding habitat, as well 
as extensive portions of western interior and Baja California, Mexico 
coastal habitat, though not all such locations were surveyed every year 
(Palacios et al. 1994). During this same time period, 10 U.S. coastal 
and 4 western interior nesting studies were also conducted at sites 
along the entire Oregon Coast, Utah, eastern Oregon, and numerous 
locations on the California coast and interior (G. Page, in litt. 
2004b). Nesting studies involve repeated searching and monitoring of 
nests and nesting areas over the course of at least one breeding 
season, and are more comprehensive than surveys.
    A total of 907 banded plovers were detected by these breeding 
surveys and studies. It is important to note that this figure does not 
include plovers that were resighted in their original region (coastal 
or western interior) without evidence of nesting, and does not include 
plovers that were banded on the coast during the winter, as their 
breeding range could not be established. The total does include six 
plovers that were found nesting in more than one location, and so were 
counted twice. Of these 907 resighted plovers, only 13 (1.4 percent) 
were found in a geographic area (coastal or western interior) that was 
different from their original breeding range. Two of those 13 plovers 
(0.2 percent of the total 907 birds) were found nesting outside of 
their original breeding range. One of these two plovers, a coastal 
female nesting at the Kesterson National Wildlife Refuge in 1986, was 
one of the two birds mentioned in the original listing rule (Service 
1993 (58 FR 12864)). The other was a male banded in the interior 
(though never found nesting in the western interior) and later found 
nesting on the coast in 1995. The other 11 plovers were all coastally 
banded and found in the interior without nests (G. Page, in litt. 
2004b).

[[Page 20615]]

    In addition to the 1984 through 1993 period, the period from 1977 
through 1983 provides another opportunity to detect movements between 
the western interior and Pacific Coast WSP populations. However, 
surveys were less comprehensive during this time period, and only one 
banding study took place in the western interior. Therefore, this 
period is less useful for assessing breeding dispersal, but still 
provides additional relevant information. During this period, 599 
plovers were banded at seven sites along the central California coast, 
and 400 were banded in the western interior at Mono Lake, California 
(G. Page, in litt. 2004b). The coastal survey effort included seven 
breeding season surveys across the U.S. range of the coastal 
population, as well as seven nest monitoring studies from Marin to San 
Luis Obispo Counties, California. The interior survey effort included 
three breeding season surveys, as well as the ongoing banding studies 
at Mono Lake (L. Stenzel, pers. comm. 2004). None of the plovers banded 
at Mono Lake were observed on the coast during the breeding season. One 
female, banded as a chick at Monterey Bay along the California coast, 
was found nesting at Mono Lake in 1978. This was the first of the two 
females mentioned in our original listing determination (Service 1993 
(58 FR 12864)) as having bred outside the coastal population.
    In addition to colored bands, whose combinations were administered 
by the Point Reyes Bird Observatory (PRBO), some studies employed metal 
bands administered by the Patuxent Bird Banding Lab. Resightings of 
these bands were less common, since recapture of the bird is generally 
required to read the band number. Of the 304 band retrievals reported 
to Patuxent Bird Banding Lab for years 1969 to 2002, one male was found 
to have moved from the Pacific coast to an interior location. This 
plover was banded during the non-breeding season (November 1984) near 
Ano Nuevo, California, and retrieved during the breeding season (June 
1988) near Lake Albert, Oregon (G. Goldsmith, in litt. 2004). The 
banding dates and associated migration suggest that the plover was an 
interior bird overwintering on the California coast. The age of the 
plover was unknown at the time of banding. There are no records in this 
data set of plovers moving in the opposite direction, from the western 
interior to Pacific coast.

Review of Banding Data

    We asked six researchers familiar with avian banding studies to 
examine the available banding data for the Pacific Coast WSP and 
plovers from the interior west of the Rocky Mountains, and provide us 
their professional opinions about the adequacy of those studies for 
determining reproductive separation between the two populations. Four 
of the reviewers responded. Three concluded that there appears to be 
little exchange of reproductive individuals between the western 
interior and coastal sites (G. Smith, USGS, in litt. 2004; B. Andres, 
Service, in litt. 2005; J. Plissner, ABR Inc., in litt. 2005). However, 
three of the reviewers (the fourth reviewer and two of the three 
reviewers mentioned above) also noted that because monitoring in the 
interior had been less comprehensive than on the coast, there is more 
uncertainty about the ability to detect coastal plovers that may have 
moved to the interior (B. Andres, in litt. 2005; C. Elphic, University 
of Connecticut, in litt. 2005; J. Plissner, in litt. 2005). They felt 
it was possible that a coastal breeding plover could move to the 
interior undetected, but it was highly unlikely that an interior 
breeding plover could move to the coast without being observed, as the 
coastal resighting efforts were more extensive temporally and 
geographically than those at interior sites. These three reviewers 
stated that the available data are adequate to conclude that there is 
little interaction between the breeding coastal and interior 
populations. One reviewer noted dispersal between inland and coastal 
populations may be episodic and associated with temporal variation in 
breeding conditions at regional scales, and that the banding efforts 
have not been extensive enough to address this possibility for the 
range of conditions (J. Plissner, in litt. 2005).

Conclusion on Banding Data

    We find that the existing banding and resighting data are 
sufficient to document that the Pacific Coast WSP and the western 
interior breeding populations experience limited or rare reproductive 
interchange. We are most confident in the data from the 12-year period 
1983 through 1995, as that is the period with the most extensive 
banding studies and search efforts. The results from that period 
indicate that 98.6 percent of the sampled plovers were observed during 
the breeding season using the same breeding range as where they were 
originally banded. We consider the results from that period sufficient 
to document a marked separation of breeding ranges, and illustrate that 
the amount of interchange between coastal and western interior 
populations is likely to be extremely low, though not zero. Results 
from the 1977 through 1984 period and the Patuxent banding data are 
also consistent with this conclusion. Our DPS policy does not require 
complete reproductive isolation, and allows for some limited 
interchange among population segments considered to be discrete 
(Service and NMFS 1996a (61 FR 4722)). Based on the results of these 
banding and monitoring data, we conclude that the Pacific Coast WSP is 
not freely interbreeding with other members of the taxon, although some 
genetic interchange likely occurs at a very small rate. This 
constitutes a marked separation due to breeding behavior.
    The banding data also indicate that interior nesting plovers 
overwintering on the Pacific coast are likely to be obligatory 
migrants, whereas many individuals in the Pacific Coast WSP either do 
not migrate, or do so only for short distances along the coast (Page et 
al. 1995a). This behavioral difference tends to set Pacific Coast WSP 
individuals apart from the interior birds with which they may mix 
during the winter.

Additional Points on Discreteness

    The petition asserts that the Pacific Coast WSP is not highly 
isolated, and provides VAFB monitoring records from 1993 to 1999 as 
supporting documentation to demonstrate that the Pacific Coast WSP and 
western interior populations commonly interbreed. VAFB is a coastal 
Santa Barbara County breeding site. The petition contains a table 
summarizing the VAFB survey records and indicating that during 1993 to 
1999, 90 plovers present during the breeding season had hatched 
elsewhere. However, our analysis below of the VAFB monitoring records 
supports a different conclusion than that reached by the petitioners 
and instead provides additional evidence demonstrating that coastal and 
interior populations do not commonly interbreed.
    Two of the 90 non-local birds cited in the VAFB monitoring records 
came from the western interior. These two plovers were banded at Abert 
Lake (in interior Oregon) (Stern et al. 1990a) during the 1988 through 
1989 banding season and were sighted at VAFB (on the California coast) 
on July 29, and August 19, 1993, during the breeding season (Persons 
1994). However, as noted by Persons (1994), post-breeding migration of 
plovers typically begins in early July, so only late June censuses 
accurately reflect the size of the breeding population. Later censuses 
include many non-breeding plovers. Stenzel et al. (1994) also report 
that after the first few days of July, plovers that move into a 
breeding area do not nest in the area. Therefore, sightings made only 
after the

[[Page 20616]]

first week in July, unless supported by evidence of breeding, are not 
good evidence of population interchange.
    The other 88 plovers in the VAFB monitoring records had all hatched 
on the coast, and were, therefore, also members of the coastal 
population (Stenzel et al. 1994). Such data tend to support our 
determination that the Pacific Coast WSP is discrete, as these data 
show that coastal population members tend to interbreed among 
themselves rather than with interior birds. These results are also 
consistent with additional studies, which found western snowy plovers 
renesting in new locations after having either lost or successfully 
fledged their first clutch (Warriner et al. 1986; Stenzel et al. 1994). 
For the Pacific Coast WSP, it is also common for one partner, usually 
the female, to abandon a brood between hatching and fledging and to 
start a new clutch in a new location with a new partner. Distances 
traveled to new nesting locations range from meters to hundreds of 
kilometers (Warriner et al. 1986; Stenzel et al. 1994). However, no 
such mid-season location changes have been shown to result in nesting 
at both coastal and interior sites.

Genetics

    Evidence of genetic distinctness can inform our analysis of the 
discreteness of a population. In determining whether the test for 
discreteness has been met under our DPS policy, we consider available 
genetic evidence, but such evidence is not required to recognize a DPS. 
The petition questions the validity and effectiveness of using banding 
studies, as compared to genetics, for investigating levels of gene 
flow. When conducted properly, we find that both banding and genetics 
studies provide useful information. The petition relies heavily on a 
master's thesis (Gorman 2000) that did not find evidence of genetic 
differentiation between the Pacific Coast WSP and western interior 
snowy plover populations using mitochondrial DNA (mt DNA).
    Several commenters also pointed out that mtDNA markers in Gorman's 
study may have been indicating interbreeding that happened thousands of 
years ago and suggested that additional studies using a marker with a 
finer resolution, such as microsatellite comparisons, should be 
conducted (B. Crespi, in litt. 2002; J. Neigel, in litt. 2004; B. 
Foster, in litt. 2004; L. Gorman, in litt. 2004). In fact, a more 
recent study by Funk et al. (2006) includes analysis of microsatellite 
DNA markers. Funk et al. (2006) found no statistically significant 
genetic differentiation between Pacific Coast WSP and western interior 
snowy plover populations using mtDNA and microsatellite DNA markers.
    Given these available data indicating that the mtDNA and 
microsatellite data show no evidence of significant genetic 
differentiation between Pacific Coast and interior WSP populations, the 
Service's responsibility is to interpret the result in terms of our DPS 
policy. As noted in Funk et al. (2006), ``only a few dispersers per 
generation are necessary to homogenize gene pools between breeding 
habitats (Wright 1931; Slatkin 1985, 1987; Mills and Allendorf 1996).'' 
Therefore, failure to identify genetic differences between Pacific 
Coast and western interior plovers does not necessarily mean that there 
is a large amount of movement between the two areas. Movement of just a 
few individuals may prevent genetic differentiation, but movement of a 
few individuals may not be sufficient to maintain significant 
demographic connectivity (Funk et al. 2006).
    Thus, the two regions (in this case, the Pacific Coast and western 
interior populations) may continue to function as demographically 
independent populations despite sufficient gene flow to homogenize gene 
pools (which may require just a few individuals per generation) (Funk 
et al. 2006). That the two may be demographically independent, as noted 
by Funk et al. (2006), is particularly likely given that they have 
unique habitats (e.g., Pacific Coast birds tend to occur, with some 
exceptions, on open sandy beaches adjacent to the Pacific Ocean, while 
Great Basin birds occur on sand/salt flats on alkali lakes of the Great 
Basin (Page et al. 1995), low dispersal rates (Page, in litt. 2004a), 
and population declines (Page et al. 1991). Funk et al. (2006) suggest, 
for example, that ``if a Pacific Coast population of snowy plovers went 
extinct, a few immigrants from the Great Basin [interior] may not be 
sufficient to recolonize the empty habitat patch.'' They further 
suggest that empty patches of Pacific Coast habitat are not currently 
being recolonized in this fashion and that there is no reason to expect 
they would be recolonized in the future when habitat is even further 
fragmented.
    In summary, the genetic information available to us in Gorman 
(2000) and Funk et al. (2006) shows no evidence of genetic 
differentiation between Pacific Coast and western interior WSP, using 
mtDNA and microsatellite markers. For this reason, we do not find that 
the genetics data currently available to us provide evidence that 
Pacific Coast WSP is ``markedly separated'' from western interior 
populations of WSP. However, as outlined above and articulated in Funk 
et al. (2006), it is reasonable to conclude that other data (i.e., 
besides genetic data) are relevant to an analysis of whether WSP from 
these two geographic regions can be considered ``markedly separated'' 
(i.e., discrete) per our DPS policy. As noted above in the Banding and 
Monitoring Information section, we believe there is substantial 
evidence from banding data to indicate that exchange of individuals 
between the Pacific Coast and western interior regions is minimal.

Conclusion on Discreteness

    Based on the available information in the petition, scientific 
literature, and in our files regarding western snowy plover range and 
distribution, we conclude that the Pacific Coast WSP is markedly 
separate from other populations of the subspecies due to behavioral 
differences and that it, therefore, meets the requirements of our DPS 
policy for discreteness. Banding studies and resighting efforts 
demonstrate that during breeding, the Pacific Coast WSP segregates 
geographically from other members of the subspecies, even those that 
also winter on the Pacific coast. Although not absolute, this 
segregation is marked and significant.

Significance

    Under our DPS policy (61 FR 4722), once we have determined that a 
population segment is discrete, we consider its biological and 
ecological significance to the larger taxon to which it belongs. This 
consideration may include, but is not limited to, the following 
factors:
    1. Persistence of the discrete population segment in an ecological 
setting unusual or unique for the taxon,
    2. Evidence that loss of the discrete population segment would 
result in a significant gap in the range of the taxon,
    3. Evidence that the discrete population segment represents the 
only surviving natural occurrence of a taxon that may be more abundant 
elsewhere as an introduced population outside its historic range, or
    4. Evidence that the discrete population segment differs markedly 
from other populations of the species in its genetic characteristics.
    We evaluated available information to assess whether the 1993 
designation was consistent with the above factors or other relevant 
factors to explain why the Pacific Coast WSP is significant to the 
subspecies of western snowy plover. In this finding, we are only 
addressing the significant gap in the range of the taxon because that 
is the only significant criteria factor that applies.

[[Page 20617]]

Significant Gap in the Range of the Taxon

    One approach to assessing whether the Pacific Coast WSP constitutes 
a substantial portion of the western snowy plover subspecies (Pacific 
Coast, interior, and Gulf Coast) is to evaluate the size of the 
subspecies. Estimating size of a broadly yet patchily distributed 
subspecies like the western snowy plover is a difficult task to 
accomplish (Gorman and Haig 2002). At this time, our best available 
estimate of the subspecies' current total size is about 24,136 birds 
(Page et al. 1995a; P. Paton, University of Rhode Island, in litt. 
2004; Zdravkovic 2004; Gorman and Haig 2002; L. Kelly in litt. 2006; M. 
Jensen in litt. 2006; G. Page in litt. 2005) (see Table 1).
    The estimate in Table 1 of the total number of birds of the 
subspecies takes into account the following new data: Dr. Peter Paton 
recently revised his original published estimate of 10,600 birds for 
Utah (Page et al. 1995a) to 4,189 birds (P. Paton, in litt. 2004). 
Stenzel provides information that the 4,478 figure used to describe the 
Pacific Coast WSP population through the 2004 breeding season is likely 
an underestimate due to some areas in southern California not being 
surveyed (L. Stenzel, in litt. 2004a). The new observed estimated 
number of birds (3,695) is based on the 2005 breeding season (see Table 
1 above), which is approximately a 3 percent drop from Stenzel's 2004 
figure. Additionally, researchers in Texas believe that as many as 
1,000 plovers nested along the Texas Gulf coast in 2004, a substantial 
increase from the 100 reported by Page et al. (1995a) (Zdravkovic 
2004). We are not aware of what effect, if any, the 2005 hurricanes may 
have had on the Gulf coast plovers and their habitat.
    Monitoring results are not available for the interior and northeast 
coastal Mexico areas, and recent estimates have not been developed for 
several of the interior western snowy plover breeding areas. In light 
of this inconsistent survey coverage, we considered it appropriate to 
use the largest of the available estimate ranges available for the 
interior breeding plovers, so as not to overstate the significance of 
the Pacific Coast WSP. We acknowledge that the number of birds within 
the subspecies could be more or less than that indicated by the best 
available information. As presented in Table 1 above, the Pacific Coast 
WSP current population estimate is approximately 20 percent of the 
taxon's total estimated size (4,804 of 24,136 total birds). Therefore, 
we contend that using this conservative interpretation of the best 
available data, the 2005 Pacific Coast WSP constitutes approximately 20 
percent of the subspecies.
    The petition also states that because the range of interior western 
snowy plovers overlaps that of Pacific Coast WSP (by virtue of sharing 
winter ranges), they have ``ample opportunity to socialize, pair bond, 
and inter-breed.'' We agree that the potential exists for interactions 
to occur between wintering interior western snowy plovers and Pacific 
Coast WSP, but banding data indicate that such interactions occur at 
very low rates.
    The petition suggests, without any supporting evidence, that 
interior-nesting western snowy plovers would colonize the coastal 
breeding habitat if the Pacific Coast WSP were extirpated. As described 
earlier, the Pacific Coast WSP population declined during the 1970s to 
mid-1990s, leaving many historical breeding locations vacant throughout 
the coastal range, and even though ample habitat remained intact, it 
was not colonized by any plovers (coastal or interior). Analysis of the 
available banding data indicates that there is little interchange 
between the coastal and interior breeding populations (G. Smith, USGS, 
in litt. 2004; B. Andres, Service, in litt. 2005; J. Plissner, ABR 
Inc., in litt. 2005). Although low levels of breeding dispersal from 
the coast to the interior remain a possibility, the banding studies 
provide a high degree of confidence that any such dispersal is out of 
the coastal population, and not into it (C. Elphic, in litt. 2005). 
This is consistent with additional analysis indicating that the 
available banding data are adequate to conclude that an insignificant 
number of individual plovers disperse from interior breeding sites to 
coastal breeding sites (J. Plissner, in litt. 2005), and it is unlikely 
that interior breeding plovers would disperse to coastal breeding sites 
(B. Andres, in litt. 2005). We have no data documenting interior birds 
colonizing vacant coastal areas.
    This apparent lack of interchange between coastal and western 
interior breeding sites may be explained by the relatively high degree 
of site fidelity exhibited by this species. Breeding and winter site 
faithfulness vary between sites. Stenzel et al. (1994) report that 
plovers were faithful to their known breeding location in northern-
central coastal California about 59 percent of the time for females and 
84 percent of the time for males. Partial-absence (missing for a 
portion of the breeding season) from known breeding locations was more 
common than complete absence. Of the 147 birds observed moving during 
the breeding season, 25 females and 14 males moved from 50 to 708 miles 
(31 to 1,140 kilometers). All 147 birds remained within the coastal 
zone, either north or south of their previously known breeding 
location. There was no evidence of pair movements, only movements for 
individual plovers. Page et al. (1995a) present the following adult 
plover resighting rates at breeding locations between consecutive 
years: Monterey Bay, California, males 76.8 percent, females 65.8 
percent (Warriner et al. 1986); Mono Lake, California, males 77.8 
percent, females 44.9 percent (Page et al. 1983); Lake Abert, Oregon, 
males 64.1 percent, females 40.9 percent (Stern et al. 1990a). There is 
also evidence of fidelity to wintering areas. About two-thirds of 
plovers banded during the breeding season at Lake Abert, Oregon, were 
located on their coastal California or Baja California, Mexico, 
wintering areas for 2 subsequent years, and about one-third were 
subsequently located at least 3 years following banding (Page et al. 
1995b).
    There is no evidence to indicate western interior populations would 
recolonize the Pacific coast if the listed population were lost. 
Therefore, such loss would remove 2,000 miles of coastline, stretching 
from Washington to Baja California, from the subspecies' breeding 
range. The Pacific coast constitutes the vast majority of coastal 
breeding habitat used by the subspecies (the rest being in southern