# Endangered and Threatened Wildlife and Plants; Withdrawal of the Proposed Rule To List the Mountain Plover as Threatened

> Briefs, arguments, decisions, and more.

URL: https://www.frixlaw.com/law-library/documents/fr%3A2011-11056

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** May 12, 2011
- **Citation:** 76 FR 27756

## Text

DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R6-ES-2010-0038; MO 92210-0-0008-B2]
RIN 1018-AX26
Endangered and Threatened Wildlife and Plants; Withdrawal of the Proposed Rule To List the Mountain Plover as Threatened

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Proposed rule; withdrawal.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), announce our decision to withdraw the proposed listing of the mountain plover (
Charadrius montanus
) as a threatened species under the authority of the Endangered Species Act of 1973, as amended (Act). After a thorough review of all available scientific and commercial information, we have determined that the species is not endangered or threatened throughout all or a significant portion of its range. We make this determination because threats to the species as identified in the proposed rule are not as significant as earlier believed and currently available data do not indicate that the threats to the species and its habitat, as analyzed under the five listing factors described in section 4(a)(1) of the Act, are likely to endanger the species in the foreseeable future throughout all or a significant portion of its range.

DATES:

The December 5, 2002 (67 FR 72396), proposal to list the mountain plover as a threatened species is withdrawn as of May 12, 2011.

ADDRESSES:

This finding is available for viewing on the Internet at
http://www.regulations.gov
(see Docket No. FWS-R6-ES-2010-0038) and
http://www.fws.gov/mountain-prairie/species/birds/mountainplover
and also by appointment, during normal business hours, at the U.S. Fish and Wildlife Service, Colorado Ecological Services Office, 134 Union Boulevard, Suite 670, Lakewood, CO 80225; telephone 303-236-4773; facsimile 303-236-4005. Please submit any new information, materials, comments or questions concerning this finding to the Colorado Ecological Services Field Office at P.O. Box 25486, DFC (MS 65412), Denver, Colorado 80225.

FOR FURTHER INFORMATION CONTACT:

Susan Linner, Field Supervisor, U.S. Fish and Wildlife Service, Colorado Ecological Services Field Office (see
ADDRESSES
). If you use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Background

Previous Federal Actions

For a detailed description of Federal actions concerning the mountain plover, please refer to the February 16, 1999, proposed rule to list the species (64 FR 7587); the December 5, 2002, proposed rule to list the species with a special rule under section 4(d) of the Act (16 U.S.C. 1531
et seq.
) (67 FR 72396); and the September 9, 2003, withdrawal of the proposed rule to list the species (68 FR 53083).

The document we published on September 9, 2003 (68 FR 53083), withdrew the entire proposed rule we published on December 5, 2002 (67 FR 72396), including our proposal to list the mountain plover as a threatened species and our proposed special 4(d) rule. The September 9, 2003, document also addressed comments we received on both the 1999 and 2002 proposals to list the mountain plover and summarized threat factors affecting the species. The withdrawal of the proposed rule was based on our conclusion that the threats to the mountain plover identified in the proposed rule were not as significant as previously believed and that currently available data did not indicate that threats to the species and its habitat, as analyzed under the five listing factors described in section 4(a)(1) of the Act, were likely to endanger the species in the foreseeable future throughout all or a significant portion of its range.

On November 16, 2006, Forest Guardians (now WildEarth Guardians) and the Biological Conservation Alliance filed a complaint in the District Court for the Southern District of California challenging the September 9, 2003, withdrawal of the proposal to list the mountain plover (68 FR 53083). We entered into a settlement agreement with the plaintiffs, which was filed by the court on August 28, 2009. As part of the settlement agreement, we agreed to reconsider our decision to withdraw the proposed listing of the mountain plover and to submit to the
Federal Register
by July 31, 2010, a document reopening the December 5, 2002, proposal to list the mountain plover (67 FR 72396) that would also request public comments. We agreed to vacate our 2003 withdrawal of the proposed rule upon publication of the
Federal Register
notice reopening public comment on the December 5, 2002, proposal to list the mountain plover (67 FR 72396). We further agreed to submit a final listing determination for the mountain plover to the
Federal Register
no later than May 1, 2011.

On June 29, 2010, we published a document in the
Federal Register
notifying the public that we were reinstating that portion of our December 5, 2002, proposed rule to list the mountain plover as threatened under the Act (75 FR 37353). We did not reinstate that portion of the December 5, 2002, proposed rule regarding a proposed special rule under section 4(d) of the Act. The proposed special rule was designed to allow researchers to complete field research and analyze data for an ongoing study, and addressed agricultural activities only through December 31, 2004. To ensure that our review of the species' status was complete and based on the best available scientific and commercial information, we requested comments on the proposal to list the mountain plover as a threatened species, including all information related to the species' status and the proposed listing. We invited public comments on the proposed listing, new information relevant to our consideration of the status of the mountain plover, and comments and information regarding threats to the species and its habitat.

Species Information

Our February 16, 1999, and December 5, 2002, proposed rules (64 FR 7587 and 67 FR 72396, respectively), and our September 9, 2003, withdrawal of our 2002 proposal to list the mountain plover (68 FR 53083) described the species' life history, ecology, and habitat use. For additional background on the natural history of the mountain plover, see the account of the species in
The Birds of North America
(Knopf and Wunder 2006).

While the majority of relevant information directly pertaining to the mountain plover that has become available since our December 5, 2002, proposal to list (67 FR 72396) and September 9, 2003, withdrawal of that proposal (68 FR 53083) has resulted from local or Statewide studies on the mountain plover's breeding range; two recent documents provide extensive review of current knowledge regarding the mountain plover:

(1) Mountain Plover (
Charadrius montanus
) in
Birds of North America
(Knopf and Wunder 2006); and

(2) Conservation Plan for the Mountain Plover (
Charadrius montanus
), Version 1.0 (Andres and Stone 2009).

Numerous other recent documents are summarized in our June 29, 2010, notification reinstating our December 5, 2002, proposed rule to list the mountain plover as threatened under the Act (75 FR 37353). These include over twenty peer-reviewed journal articles, and many other reports and summaries relevant to the status of the mountain plover that have become available since 2002.

The following sections highlight and update information on the mountain plover with emphasis on information developed since 2002.

Taxonomy and Species Description

The mountain plover (
Charadius montanus
) is a small bird in the order Charadriiformes, family Charadriidae. No subspecies are recognized. It is a migratory, terrestrial shorebird averaging 8 inches (21 centimeters) in body length. Mountain plover are light brown above and white below, but lack the contrasting dark breast band characteristic of several other plovers such as the more common killdeer (
C. vociferus
). Sexes are similar in appearance.

Feeding Habits

Mountain plover feed on ground-dwelling invertebrates and flying invertebrates found on the ground, primarily beetles, crickets, and ants. They forage with a series of short runs and stops, feeding opportunistically as they encounter prey (Knopf and Wunder 2006, unpaginated).

Breeding

Mountain plover return north to their breeding sites in the western Great Plains and Rocky Mountain States in spring. They arrive at their breeding grounds in northeastern Colorado in late March (Graul 1975, p. 6). Arrival is earlier farther south and later in Montana and at higher elevations in South Park, Colorado (Knopf and Wunder 2006). Mountain plover are territorial during the breeding season, with males defending territories shortly after arrival (Knopf and Wunder 2006). Mountain plover are generally monogamous; they form pairs and begin courtship on arrival at their breeding grounds. Nests consist of a simple ground scrape. Egg laying in northeastern Colorado begins in late April and extends through mid-June (Graul 1975, p. 7). Graul (1973, p. 84) described mountain plover nesting as a “rapid multi-clutch system.” The female normally produces two clutches, typically three eggs each, at different nest sites; the male incubates the first nest site while the female incubates the second. If the first nest or brood is lost early in the breeding season, the adult may renest, so each pair can potentially make four attempts per year to raise a brood. This breeding system may increase breeding success given predation that occurs on mountain plover nests or broods. This breeding system, rare among bird species, may result in greater reproductive potential than in other shorebirds (Knopf and Wunder 2006). It may have developed in response to food fluctuations that typically occur in the shortgrass prairie, where insect populations likely fluctuate in response to annual, seasonal, and local fluctuations in precipitation (Graul 1973, p. 85).

Average incubation period is 29 days (Graul 1975, p. 19). Chicks leave the nest within hours of hatching and obtain their own food. Only one adult normally tends each nest and brood. The minimum habitat requirement for mountain plover broods in Montana was 70 acres (ac) (28 hectares (ha)) (Knopf and Rupert 1996, p. 33), and brood home ranges averaged 143 ac (57 ha) on rangeland in Colorado (Knopf and Rupert 1996, p. 31). Brood home ranges appeared similar for three Colorado landscapes (Dreitz and Knopf 2007, p. 129). Parents stay with chicks until they fledge, which occurs at about 33 to 34 days (Graul 1975, p. 25). Mountain plover breed their first spring and every year thereafter (Knopf and Wunder 2006).

Habitat and Range

Although often thought of as a grassland species, the mountain plover may best be described as a species of disturbed prairie or semi-desert habitat (Knopf and Miller 1994, p. 505). They are found on open, flat lands including xeric (extremely dry) shrublands, shortgrass prairie, barren agricultural fields, and other sparsely vegetated areas. On grasslands, they often inhabit areas with a history of disturbance by burrowing rodents such as prairie dogs (
Cynomys
spp.), native herbivores, or domestic livestock.

Mountain plover breed from Canada (extreme southern Alberta and Saskatchewan) to northern Mexico (Figure 1) with greatest apparent numbers in Colorado and Wyoming, and substantial numbers in Montana, New Mexico, and Nebraska. In Mexico, breeding populations are suspected in the States of Chihuahua, Cohuila, and Nuevo Leon (Andres and Stone 2009, p. 9).

BILLING CODE 4310-55-P

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Mountain plover winter in similar habitat, many in California, but also in southern portions of Arizona, Nevada, New Mexico, Texas, and in northern Mexico. While California's Sacramento, San Joaquin, and Imperial Valleys support the greatest documented concentrations of wintering mountain plover, relatively little is known about wintering numbers or distribution in other areas.

Breeding Habitat

Common elements of mountain plover breeding habitat include short vegetation, bare ground, and flat topography. The mountain plover historically nested in a region impacted by a variety of herbivores, including prairie dogs, bison (
Bison bison
), and pronghorn antelope (
Antilocapra americana
), because these heavily grazed or similarly disturbed landscapes support reduced height and density of vegetation, creating favorable breeding habitat for mountain plover. While the mountain plover is categorized as a shorebird, it is seldom found near margins of freshwater or marine estuaries. Dinsmore (2003, pp. 14-17) described four types of breeding habitat: Short- and mixed-grass prairie, prairie dog colonies, agricultural lands, and semi-desert.

On the plains, the mountain plover is generally considered an associate of the shortgrass prairie, dominated by blue grama (
Bouteloua gracilis
) and buffalo grass (
Buchloe dactyloides
) (Knopf and Miller 1994, p. 504). In the Pawnee National Grasslands (PNG) in northern Weld County, Colorado, an area that formerly supported the greatest known concentration of breeding mountain plover, breeding habitat was described as restricted to flat, heavily grazed areas (Graul 1973, p. 69). Native prairie grasslands formerly presented a diverse ecosystem, shaped by low precipitation, grazing, and fire. Today, prairie landscapes often consist of grassland fragments where current cattle grazing practices tend to create relatively uniform grass coverage and height, which is not beneficial to mountain plover (Knopf 2008, pp. 55-57). Typical range management practices such as rotational grazing, limited grazing, and improving soil moisture are designed to promote taller grasses that limit mountain plover use. Within these landscapes, areas of cattle concentration (loafing areas and near water), disturbance caused by prairie dogs, and plowed or fallow (unseeded for one or more seasons) agricultural fields create conditions favorable for mountain plover nesting (Knopf and Wunder 2006). Mountain plover are also attracted to burned areas in their breeding grounds, and burning may be valuable as a habitat management tool (Knopf 2008, pp. 25-26, 57-58, 61; Andres and Stone 2009, p. 34).

Prairie dog colonies create important habitat for mountain plover, and are especially important to maintaining mountain plover populations in the northern portions of their range (Dinsmore
et al.
2003, pp. 1024-1025; Dinsmore
et al.
2005, p. 1552; Augustine
et al.
2008, unpaginated; Childers and Dinsmore 2008, p. 705; Tipton
et al.
2009, pp. 496-497; Dreitz 2009, pp. 875-877). Active prairie dog colonies provide exposed soils around burrows and, because prairie dogs keep surrounding vegetation clipped, an area of low-growing, perennial vegetation that is suitable as mountain plover breeding and brood-rearing habitat. In addition, prairie dogs give alarm calls in response to the approach of predators and may alert mountain plover to predator presence. The density of mountain plover was found to be much greater on black-tailed prairie dog (
C. ludovicianus
) colonies than on other habitats in Montana (Childers and Dinsmore 2008, pp. 705-706). In north-central Montana, the size of the adult mountain plover population closely tracked annual changes in the area occupied by black-tailed prairie dogs (Dinsmore
et al.
2003, p. 1024). Both prairie dog and mountain plover numbers declined sharply in the mid-1990s in response to an outbreak of sylvatic plague, which caused deaths of prairie dogs and resultant loss of favored mountain plover habitat. Mountain plover later increased in concert with subsequent increases in prairie dogs (Dinsmore
et al.
2005, pp. 1550-1552).

In the Colorado shortgrass prairie ecosystem, mountain plover densities observed on black-tailed prairie dog colonies were higher than those on dryland agriculture and much higher than those on grasslands without prairie dogs (Dreitz
et al.
2006, p. 702; Tipton
et al.
2009, p. 496). Mountain plover were significantly more abundant on black-tailed prairie dog colonies than on other rangeland within a bison pasture in northeastern New Mexico (Groguen 2010, pers. comm.). Prairie dog colonies occupied by mountain plover were, on average, larger in size than colonies with no mountain plover. In Utah, mountain plover nested in proximity to white-tailed prairie dog (
C. leucurus
) colonies (Manning and White 2001, p. 226). In northeastern Mexico, breeding mountain plover were associated with Mexican prairie dog (
C. mexicanus
) colonies (Gonzales-Rojas
et al.
2006, p. 82).

Mountain plover have been found to regularly use fallow or plowed agricultural fields for nesting (Shackford
et al.
1999, entire; Dreitz and Knopf 2007, pp. 684-685; Bly
et al.
2008, p. 127; McConnell
et al.
2009, pp. 30-33). Where mountain plover have an opportunity to choose between agriculture and prairie, they may use both equally (Knopf and Rupert 1999, p. 84). Shackford
et al.
(1999, entire) found mountain plover nesting on cultivated fields in Colorado, Oklahoma, Kansas, and Wyoming. Fifty percent of all nests they encountered during their research were on fallow or bare fields. While many nests were destroyed by farm machinery, they concluded that mountain plover were using cultivated fields successfully for nesting, especially in southern portions of the species' range (Shackford
et al.
1999, p. 117).

Recent studies addressed the mountain plover's nesting ecology, and attempted to identify the extent of breeding distribution and population size in Nebraska (Bly
et al.
2008). They encountered 272 nests on agricultural fields of cultivated wheat and millet (Bly
et al.
2008, p.123). Studies in Oklahoma encountered mountain plover on bare agricultural fields (90 percent of observations), with few (5 percent of observations) associated with prairie dog towns (McConnell
et al.
2009, pp. 31-32).

It remains unknown whether Texas or Mexico crop fields support mountain plover breeding (Andres and Stone 2009, p. 24). Holliday (2010) reported that breeding season sightings of mountain plover from the Texas Panhandle tended to be in cultivated fields as in adjacent Oklahoma, although previously reported nesting in West Texas was in grazed, short-grass habitat.

Knopf and Wunder (2006) described mountain plover as breeding “more predictably” at semi-desert locations west of the shortgrass prairie in Colorado, Wyoming, and Montana. Beauvais and Smith (2003, entire) developed a model of mountain plover breeding habitat in shrub-steppe habitat of western Wyoming. They related favored patches of mountain plover breeding habitat to poor soils, low precipitation, and wind scour, features they predicted would persist over time, especially on public lands. In such habitats, mountain plover are less dependent on prairie dog colonies to create breeding habitat. A Wyoming study located 55 mountain plover nests in grassland or desert scrub habitat in six counties (Plumb
et al.
2005a, p. 225). All nest sites were grazed by ungulates with prairie dogs present at only 36 percent of nest sites, mostly in grassland (Plumb
et al.
2005a, pp. 226-227). In Montana, Childers and Dinsmore (2008, p. 107) noted that sparsely vegetated, hardpan clay flats provided nesting habitat.

In summary, mountain plover require short vegetation with some bare ground on their breeding sites. In grasslands, this usually requires disturbance, such as that provided by prairie dogs, cattle grazing, fire, or farming. In semi-desert environments, breeding habitat may persist without these forms of disturbance.

Migration and Wintering Habitat

Southbound migration of mountain plover is prolonged, with post-breeding flocks numbering in the hundreds forming in late June with some remaining on breeding areas until September or October (Bly
et al.
2008, p. 123; Andres and Stone 2009, p. 10). Mountain plover migrate southward across the southern Great Plains in late summer and early fall to Texas, New Mexico, and Mexico, with many then traveling west to California (Knopf and Wunder 2006). During spring migration, mountain plover move from their

wintering sites in early March and proceed quickly to breeding sites in eastern Colorado by mid-March and in Montana by mid-April (Knopf and Wunder 2006). Mountain plover are generally thought to use habitats similar to those on the breeding and wintering grounds during migration. During migration, they have also been reported using alkaline or mud soils, and sod farms (Knopf and Wunder 2006). Few studies have been conducted on stopover habitat, and little is known about stopover ecology or food resources exploited (Andres and Stone 2009, pp. 14, 21, 37).

In winter, mountain plover use habitats similar to those on their breeding grounds. Mountain plover are found wintering in California mostly on fallow and cultivated agricultural fields, but also on grasslands and grazed pastures (Hunting
et al.
2001, p. 39; Knopf and Wunder 2006).

Throughout the Central Valley of California, the field types used by mountain plover vary seasonally, from uncultivated lands in October and November, shifting toward cultivated lands over the winter (Hunting and Edson 2008, pp. 183-184). Mountain plover wintering in the San Joaquin Valley of California used tilled fields, grazed pastures, alkali flats, and burned fields, but they preferred native valley sink scrub (low vegetation dominated by alkali-tolerant shrubs) and nonnative grazed or burned grasslands over any of the more common cultivated land types (Knopf and Rupert 1995, pp. 747-749). Winter habitat availability in California's Carrizo Plain seems linked to a combination of livestock grazing and precipitation, with heavy grazing and dry conditions creating conditions most favorable to the mountain plover. Giant kangaroo rat (
Dipodomys ingens
) precincts (colonies) are also used, especially when wet years produce tall vegetation elsewhere (Sharum 2010, pers. comm.).

Mountain plover exclusively used cultivated sites in the Imperial Valley of California (Wunder and Knopf 2003, pp. 74-75). While cultivated lands are abundant throughout the Imperial Valley, not all provide suitable feeding habitat. Mountain plover were found to favor irrigated farmland, including burned bermudagrass (
Cynodan dactylon
); harvested, grazed, or sprouting alfalfa (
Medicago spp.
) fields; and newly cultivated fields (Wunder and Knopf 2003, pp. 75-76; AMEC Earth and Environment 2003, p. 12). Fallow fields were used mostly for roosting, and melon and vegetable fields were rarely or never used (Wunder and Knopf 2003, pp. 75-76). Insect availability, furrow depth, size of dirt clods, and the vegetation on contiguous land parcels were all believed to influence the suitability of agricultural fields to mountain plover.

In California, annual climatic variability, especially abundant rainfall, influences field conditions and can reduce mountain plover use of traditionally occupied wintering sites. For example, mountain plover became virtually absent from cultivated fields in the Imperial Valley during the rainy winter of 2004-2005 (Knopf and Wunder 2006). Movement patterns of wintering mountain plover in California are shown to be highly variable, with birds on several occasions moving more than 34 miles (mi) (55 kilometers (km)) in a week (Knopf and Wunder 2006).

In Arizona, mountain plover winter on sod farms and grazed pastures, and are observed using the same sites yearly. Their use of farm fields and other potential habitats is generally unknown, and these areas are rarely surveyed (Robertson 2010, p. 1). A few mountain plover have wintered in recent years on mowed grasses at Gila Bend Air Force Auxiliary Field (Mendelsohn 2010).

In Texas, winter reports of mountain plover were correlated with barren fields and grazed pastures (Holliday 2010). In Williamson and Bell Counties, Texas, mountain plover winter only on large, flat, plowed fields, especially those with some corn or sorghum stubble (Fennel 2002, p. 29). In the Texas coastal bend area (Nueces and San Patricio Counties), wintering plover are largely limited to plowed fields rather than grasslands or fallow fields, with mountain plover often following tractors while feeding (Cobb 2009, pers. comm.). Wintering mountain plover in Texas have also been reported using burned fields (Knopf and Wunder 2006), sod farms (Cobb 2011, pers. comm.), coastal prairies, and alkaline flats (Andres and Stone 2009, p. 12).

In Mexico, mountain plover are found wintering in grassland areas with high densities of prairie dogs (both black-tailed and Mexican) and on heavily grazed pastures (Andres and Stone 2009, p. 12; Macias-Duarte and Panjabi 2010, pp. 5, 7). Consistent with other areas, open habitat with low grass cover and sparse or no shrub cover are elements common to areas used by mountain plover in Mexico. However, significant mountain plover use of crop fields in Mexico has not been reported (Macias-Duarte and Punjabi 2010, p. 7).

Wunder (2007) studied geographic population structure in mountain plover through color-banding and stable isotope concentrations in feathers. He concluded that there is widespread mixing of mountain plover populations in winter and that birds may use alternate wintering sites in different years (Wunder 2007, p. 118). While mountain plover appear annually at some favored wintering sites, site fidelity by individual birds appears low. Mountain plover can move long distances and use various sites even within a given winter.

Survival, Lifespan, and Site Fidelity

A long-term study on mountain plover breeding grounds in Phillips County, Montana, provides much of what is known regarding population dynamics of the species. The annual survival rate of adult mountain plover of both sexes in Phillips County ranged from 0.74 to 0.96 yearly (Dinsmore 2008, p. 50). The annual survival rate for juvenile mountain plover (survival to 1 year of age) was 0.06 at hatching, but for those chicks that reached fledging age was 0.62 (Dinsmore 2008, p. 51). Survival estimates did not account for permanent emigration (birds surviving but returning in subsequent years to sites outside of the study area), so the actual annual survival may have been higher.

Previous estimates of survival rates and of estimated mean lifespan of 1.92 years (Dinsmore
et al.
2003, pp. 1020-1021) supported our December 5, 2002, conclusion that the mountain plover had a shorter lifespan than other plovers (
Charadriidae
) (67 FR 72397) and that this might impact its opportunity to reproduce. These conclusions underestimated adult mountain plover survival. The longer study of the same population over years with varying weather and habitat conditions modified the earlier conclusions regarding the mountain plover's longevity. Mountain plover of 5 to 7 years of age were frequently encountered, and a longevity record over 10 years was established (Dinsmore 2008, p. 52). Based on this additional research, survival rates for mountain plover appear comparable to those reported for other plovers, and the mountain plover is now considered a relatively long-lived species (Dinsmore
et al.
2010, unpaginated). We no longer believe that the mountain plover's lifespan is a liability that could contribute to the negative impact of natural or manmade events affecting the species.

Mountain plover have a high nest survival rate compared to other ground-nesting species (Dinsmore
et al.
2010), but nest success in mountain plover has varied greatly from study to study. Successful hatching (of at least one egg) ranged from 26 percent (Knopf and

Rupert 1996, pp. 29-30) to 65 percent (Graul 1975, p. 18). Dinsmore
et al.
(2002, pp. 3485-3486) found differences in nest success between nests incubated by males (49 percent) and females (33 percent). Dreitz and Knopf (2007, p. 684) found nest success of 37 percent with no appreciable difference between nests on agricultural fields and on native rangeland.

There have been relatively few studies of chick survival (hatching to fledging) and results vary greatly. Dreitz (2009, p. 6) estimated that 30-day survival of chicks of mountain plover from prairie dog colony nesting habitat was 75 percent, and that 30-day survival on other grasslands and on agricultural fields was less than 25 percent. Following similar methodology, research on crop fields in Nebraska found 95 percent survival of chicks accompanying 31 adult mountain plover that were radio-tracked for the 36 days after eggs hatched (Blakesley and Jorgensen 2010). Radio contact was lost with other adults (due to birds leaving the area or transmitter failure), but even if assuming all chicks associated with these adults perished, chick survival was at least 58 percent (Blakesley and Jorgensen 2010). Dreitz
et al.
(2010) studied post-hatching chick survival (hatching to fledging) via radio-tracking in Colorado and Montana. The study targeted factors affecting survival, including landscape characteristics, with an objective of informing conservation and management efforts. Field studies in 2010 were hampered by unusually cold and wet weather. Of 93 chicks radio-tracked over three habitat types in Colorado, only 9 were confirmed to survive to 30 days (Dreitz
et al.
2010, p. 3). Thirty-eight confirmed mortalities included 13 from avian predators, 8 from mammalian predators, and 17 from unknown predation, weather, and undetermined factors. Contact with other chicks was lost, and their fates were unknown. Results did not reflect higher chick survival on prairie dog towns than on other grasslands or agricultural fields. In Montana, only 1 of 39 chicks monitored on black-tailed prairie dog colonies was confirmed to survive to 30 days. Nineteen mortalities were documented, with 13 from heavy rains (Dreitz
et al.
2010, p. 4). Sources of mortality differed among habitats in Colorado, with avian predation higher at black-tailed prairie dog towns (Dreitz
et al.
2010, p. 6). However, results of the study are considered preliminary, and future work is planned.

Few studies have estimated seasonal adult survival rates. Dreitz (2010, unpaginated) found 89 percent survival of adults with broods for the 30 days after hatching. A study of overwintering mountain plover in California showed nearly 95 percent survival of wintering birds from November 1 to March 15 (Knopf and Rupert 1995, p. 746). Since survival of adults during stationary periods is believed to be relatively high, and there is no estimate for adult survival during spring and fall migration, there is potential that losses of adults during migration may be significant and efforts to increase adult survival might be focused on migration periods (Dinsmore
et al.
2003, p. 1023; Andres and Stone 2009, p. 1; Dinsmore
et al.
2010). However, there is no scientific information available to indicate that high mortality during migration is occurring.

A life stage-specific model based on data from three breeding areas, two in Colorado and one in Montana, found that mean adult survival was the parameter that most influenced modeled population growth (Dinsmore
et al.
2010). The importance of adult survival was characterized as typical of long-lived bird species, for which repeated reproductive attempts throughout life are less important to population growth, as evidenced by low chick survival, than adult survival (Dinsmore
et al.
2010). Nest survival was comparable to, or higher than, other ground-nesting shorebirds and was less important to population growth than survival of chicks, juveniles, and adults. Large variation in estimates of chick survival led to the conclusion that to improve population viability on breeding areas, management to increase chick survival should be a priority. The authors believed such management should be emphasized over past efforts to decrease nest losses and increase hatching success (Dinsmore
et al.
2010). However, the authors conceded that management to improve chick survival is more difficult than improving hatching success and might require large-scale habitat improvement.

Mountain plover were thought to have high site fidelity to nesting locations, returning to same area where they hatched each year (Graul 1973, p. 71). Skrade and Dinsmore (2010, p. 672) quantified mountain plover dispersal on breeding sites in Montana and reported juvenile (natal) dispersal (hatching year to return at age 1) averaged 8.1 mi (13.0 km) for males and 6.3 mi (10.2 km) for females. Only 4 of 38 banded chicks returning as adults arrived back at the same black-tailed prairie dog colony where they were banded. Knopf and Wunder (2006) noted a chick that had dispersed over 30 mi (50 km) in Colorado.

The previous year's nesting success influences adult dispersal; unsuccessful adults disperse farther than successfully breeding adults (Skrade and Dinsmore 2010, p. 671). While adults rarely move far from the area where they nested the previous year, evidence of potential for year-to-year dispersal in adults is exemplified by an adult mountain plover banded on a breeding area in Colorado in 2009, that was found nesting approximately 25 mi (40 km) away in Nebraska in 2010 (Bly 2010b, pers. comm.).

Results from genetic studies suggest that gene flow among breeding areas is sufficient to offset genetic effects of small populations and reported adult fidelity to breeding areas (Oyler-McCance
et al.
2008, pp. 496-497).

Population Size and Trends

Mountain plover are difficult to detect because they are cryptically colored and in general are widely distributed at low densities (Knopf and Wunder 2006). Based on historical observations of mountain plover and extensive habitat changes, there is general agreement that the mountain plover is currently greatly reduced in numbers and range compared to their numbers and range prior to European settlement (Graul and Webster 1976, p. 265; Knopf and Wunder 2006). The mountain plover's historical breeding range is believed to have differed from that currently occupied primarily in its eastern extent, which may have encompassed the western thirds of North Dakota, South Dakota, and Nebraska, and more of western Kansas and the Texas Panhandle than is currently occupied (Graul and Webster 1976, p. 265, Knopf and Wunder 2008).

Population estimates for the species, both historical and recent, appear imprecise. Graul and Webster (1976, p. 266) estimated that mountain plover populations in Montana, Wyoming, eastern Colorado, and New Mexico then totaled 214,200 to 319,220 birds, with 20,820 in the population stronghold of Weld County, Colorado. However, Knopf and Wunder (2008) cited Graul (pers. comm.) as saying that the estimates may have been off (
i.e.,
high) by an order of magnitude (a factor of 10).

Knopf (1996, p. 12) estimated the total population of mountain plover to be about 8,000 to 10,000, based on a 1994 wintering survey in California and on assumptions regarding proportion of the wintering population observed (
i.e.,
that only half of birds wintering in California had been counted and that 1,000 to 3,000 birds wintered in Texas and other areas). We cited this estimate in our

December 5, 2002, proposed rule (67 FR 72396). In our September 9, 2003, withdrawal of our proposed listing (68 FR 53083), we again cited the Knopf estimate above and, using similar assumptions and newer California winter survey data (1998-2002), provided a rangewide estimate of 5,000 to 11,000 mountain plover. More recent studies, which estimated populations present on specific portions of the breeding range, have resulted in a higher rangewide estimate of the mountain plover breeding population. After investigating Wyoming populations, Plumb
et al.
(2005b, p. 15) estimated a minimum of 3,393 mountain plover in Wyoming (up from previous estimates of 500 to 1,500) and estimated a rangewide total of 11,000 to 14,000 mountain plover. Based on newer information, including an upward revision of estimated mountain plover numbers on the eastern Colorado plains (a conservative estimate of 8,577 birds), Tipton
et al.
(2009, p. 497) provided a rangewide estimate of 15,000 to 20,000 mountain plover. Andres and Stone (2009, p. 8) reviewed available data and provided a coarse, minimum rangewide estimate of 18,000 breeding mountain plover. Knopf and Dreitz (
in press
) concluded that the continental breeding population is “certainly larger” than the 17,500 birds estimated in Montana, Wyoming, and Colorado, citing small populations in contiguous States, a potentially significant population in New Mexico, and an unknown population in Mexico. Based on our review of recent data, including those from Nebraska (Van der Berg
et al.
2010) and New Mexico (see Breeding Range below), we estimate that the current rangewide mountain plover breeding population exceeds 20,000 birds. This was supported by Knopf (2009, pers. comm.). We have no information to indicate that this estimate reflects an actual increase in rangewide mountain plover numbers over previous, lower estimates. Instead, it likely reflects the limitations of those earlier rangewide estimates (based on mountain plover wintering in California that largely discounted birds wintering elsewhere) and more accurate recent estimates of breeding populations.

Accurate trend information for mountain plover numbers is generally lacking. Interpreting trends from the two long standing surveys, the Breeding Bird Survey (BBS) and the National Audubon Society's Christmas Bird Count (CBC), suffer from a variety of problems, including the inherent difficulties associated with using a survey of only a small portion of a total population to infer rangewide trends (Knopf and Wunder 2004, p. 1).

The BBS is a large-scale survey of North American birds that began in 1966, and is conducted during the breeding season by observers driving along roads over established routes. Knopf (1996, p. 12) cited BBS data from 1966 through 1993 as indicative of a steep decline in mountain plover numbers across their breeding range (3.7 percent per year, a decline of approximately two-thirds over the period). However, Knopf and Wunder (2004, p. 1) suggested that the timing of surveys (which occur mostly in June when mountain plover are less conspicuous) and the low densities at which mountain plover occur prevent reliable trend estimates.

Based on recent BBS data analysis (Sauer 2010a), the mountain plover has declined rangewide at an estimated rate of 2.6 percent per year for the period from 1966 to 2009 (95 percent confidence interval (CI) −6.7 to +0.6). However, for the period from 1999 through 2009, the estimated rate of decline decreased to 1.1 percent per year (95 percent CI −5.8, +9.6) (Figure 2). While neither estimate varies statistically from a stable population (at a 95 percent CI), the probability that the estimated long-term trend (1966 through 2009) is less than or equal to zero is 95 percent. The probability that the estimated short-term trend (1999 through 2009) is less than or equal to zero is 68 percent. The estimated long-term decline is consistent with the generally accepted conclusion that the mountain plover's rangewide population is currently smaller than it was in the 1960s. The more recent (1999 through 2009) estimated decline and associated CI lead us to conclude that most or all of the long-term decrease took place before 1999, that any recent declines are modest, and that the mountain plover population may be near stable.

EP12MY11.001

Sauer (2011, pers. comm.) concluded that limited regional data from the BBS (
i.e.,
the low numbers of routes reporting the species and low numbers of mountain plover observed) resulted in imprecise trend estimates within individual States and for the time periods of interest. He also concluded that BBS data only provide an imprecise summary of mountain plover population dynamics, and the limited sample size likely reflects the limitations of the roadside sampling frame in sampling mountain plover breeding populations.

We conclude that, while the BBS is the only long-term trend information available for the mountain plover on its breeding range, it is an imprecise indicator of mountain plover population trends. Given the wide confidence interval and the conclusion by Sauer (2011, pers. comm.) above, the data provide limited support for any recent (1999 through 2009) trend in mountain plover numbers. Even so, we acknowledge that this is the best available information on trends for this species and BBS survey results suggest a recent (1999 through 2009) moderated rate of decline (Figure 2). We provide long-term and recent BBS trend estimates for three States where the sample size allowed for analysis (see Conservation Status and Local Populations below), but with the same reservations regarding precision.

The CBC is an annual count performed around the end of December in which volunteers observe birds in 15-mi (24-km) radius count circles. While CBCs can be used to infer species population trends, spatial coverage is limited (Knopf and Wunder 2004, p. 1) and established count circles commonly coincide with populated areas where volunteers are available. The CBC data estimated an annual decrease of 2.8 percent in mountain plover observed from 1966 through 2007, but reliability was described as low (Butcher and Niven 2007, Appendix 1).

The vast majority of mountain plover reported in CBCs come from California and, within California, from the South Salton Sea count. Pandolfino (2009, unpaginated) submitted his analysis of CBC data for California and recognized the data's limitations, but concluded that the data reflected long-term and recent declines in mountain plover numbers wintering in California. The CBC data on mountain plover numbers is highly variable from year to year. The Salton Sea South CBC, the only CBC in the Imperial Valley, is limited in scope and does not include portions of the valley where most mountain plover have been seen (Wunder and Knopf 2003, p. 76). Inherent limitations in data collection methods (volunteers surveying small areas relative to total winter range) and lack of sufficient detections of mountain plover in California count circles (Hunting
et al.
2001, p. 40) render trend analysis uncertain. CBC data from other States and Mexico is even less representative

of wintering populations and provides no insight into possible trends for the mountain plover.

We conclude, based on observations across the mountain plover's range and BBS trend data, that a historical decline of the mountain plover has occurred since the 1960s. However, we agree with the conclusion of Andres and Stone (2009, p. 3) that precise and accurate information on recent trends in mountain plover numbers is lacking. The recent (1999 through 2009) decline estimate from BBS data is modest (1.1 percent per year) and any difference from a stable population estimate (slope of 0.0) is statistically insignificant. However, we acknowledge that the BBS data is the best available information on trends for the mountain plover and that BBS results suggest a recent (1999 through 2009) moderated rate of decline (Figure 2). The CBC wintering data are highly variable and come mostly from California, but also suggest a long-term decline. No comprehensive trend data across the mountain plover's wintering range are available. The discussion below provides information on populations and trends within States, Canada, and Mexico, where available.

Conservation Status and Local Populations

The mountain plover is listed as endangered in Canada, as a sensitive species in Alberta, and as a threatened species in Mexico (Andres and Stone 2009, p. 13; Gober 2010). The mountain plover is identified by the Service as a Bird of Conservation Concern (Service 2008), is considered “highly imperiled” in the U.S. Shorebird Conservation Plan (2004, p. 2), a category assigned to species listed as threatened or endangered nationally, and all species with significant population declines and either low populations or some other high risk factor. It is also identified as “G3-vulnerable” by NatureServe (2010). The species is listed as a sensitive species by the U.S. Forest Service (USFS) (2010) and by the Bureau of Land Management (BLM) (2000a, 2006, 2010a). It is identified as a species of global conservation concern in the American Bird Conservancy and National Audubon Watchlist, and it is listed as “near threatened” by the International Union for the Conservation of Nature (IUCN) (BirdLife International 2010). The designations discussed above may, in part, reflect population estimates at the time those designations were established. The IUCN previously (from 2004 to 2007) listed the species as “vulnerable,” a higher level of concern than “near threatened,” but changed its rating as higher rangewide population estimates emerged. The U.S. Shorebird Conservation Plan provided a rangewide estimate of 9,000 mountain plover until 2006, when the estimate was revised upward to 12,500 (Morrison
et al.
2006, p. 69).

All States within the range of the mountain plover have included the species in their Comprehensive Wildlife Conservation Strategy or Wildlife Action Plans or both (State Plans) (Arizona Game and Fish Department 2006; University of California 2005; Colorado Division of Wildlife 2006; Wasson
et al.
2005; Montana Fish, Wildlife and Parks 2005; Schneider
et al.
2005; New Mexico Department of Game and Fish 2006; Oklahoma Department of Wildlife Conservation 2005; Texas Parks and Wildlife 2005; Wyoming Game and Fish Department 2005) as either “Species of concern” or “Species of greatest conservation need.” Each State categorizes species under these designations based on available information about the status, distribution, and trend of the species in their State. They are not regulatory classifications, but rather are intended to guide resource managers in making proactive decisions regarding species conservation and data collection priorities. The State Plans are not intended to be specific action plans for any species. These designations do not result in any protection for the species. However, the mountain plover is identified as threatened in the State of Nebraska, the only State where the species is listed as endangered or threatened.

Breeding Range

Colorado

In Eastern Colorado, the shortgrass prairie ecosystem provides flat, dry breeding habitat for the mountain plover. The species occupies grasslands within prairie dog colonies, grasslands without prairie dog colonies, and dry land agricultural fields (Dreitz
et al.
2005, pp. 129-130; Tipton
et al.
2009, p. 496).

Knopf and Miller (1994, p. 504) noted the PNG, Weld County, Colorado, as a breeding stronghold for the species, but in the mid-1990s the population fell dramatically. The PNG now supports relatively few breeding mountain plover. In 2009, Knopf provided an overview of mountain plover studies on the PNG from 1986 through 2007. He suggested that mountain plover numbers on the PNG had been in decline since the late 1930s and early 1940s, and that the dramatic decline in the mid-1990s was the abrupt endpoint of a process of deteriorating habitat, exacerbated by other factors such as wet spring weather, increased predation, and the relocation of breeding mountain plover to better habitats elsewhere (Knopf 2008, p. 61).

Despite the virtual loss of the PNG population, over half of all mountain plover are thought to breed in Colorado (Andres and Stone 2009, p. 15). A recent study reported a conservative estimate of 8,577 breeding mountain plover in eastern Colorado (95 percent CI 7,511 to 35,130) (Tipton
et al.
2009, p. 497). A separate, higher elevation population in South Park, Park County, Colorado, was estimated at 2,310 adults (Wunder
et al.
2003, p. 661). Surveys through 2006 suggested a stable population in South Park, with any variation largely attributable to wet years and dry years affecting breeding conditions (Wunder 2010a). Small numbers of mountain plover also occur in Colorado's San Luis Valley (Hicks-Anderson and VerCauteren 2006, entire). Andres and Stone (2009, p. 8) provided population estimates for the United States, Canadian provinces, and Mexican States based on their review of all available information. Their estimate of 11,000 mountain plover breeding in Colorado appears appropriate given information available.

The BBS data from Colorado, 1966 through 2009 (−0.9 percent decline annually, 95 percent CI (−7.0 to 3.5)) and 1999 through 2009 (0.3 percent increase annually, 95 percent CI (−5.5 to 14.7)) (Sauer 2010a), suggest little long-term or recent change in breeding numbers in Colorado. Based on these data, we conclude that the current breeding population in Colorado, which likely supports half or more of all breeding mountain plover, is relatively stable.

Wyoming

Wyoming has the highest estimated number of breeding mountain plover outside of Colorado. The mountain plover is locally common and has been detected in every county of Wyoming (Smith and Keinath 2004, p. 3). A projected 20.5 million ac (8.3 million ha) of mountain plover habitat exists in Wyoming, with 59 percent occurring on public lands (Wyoming Natural Diversity Database (WYNDD) 2010; Emmerich 2010).

Nesting of mountain plover in Wyoming occurs in both grassland, mostly in the eastern part of the State, and desert-shrub (Plumb
et al.
2005b, p. 20). Mountain plover densities were comparable across habitat types with overall density only slightly higher in grassland than in desert-shrub (Plumb

et

al.

2005b, p. 20). Mountain plover appear to have less association with prairie dog habitat in Wyoming than elsewhere (Plumb
et al.
2005a, p. 226). Little of the mountain plover breeding range in Wyoming (approximately 12 percent) is on cropland Knopf and Rupert 1999, p. 85).

Plumb
et al.
(2005b, pp. 19-20) estimated a minimum population of 3,393 mountain plover in Wyoming in 2002 and 2003. Andres and Stone (2009, p. 8) provide an estimate of 3,400 mountain plover breeding in Wyoming. This number is based on Plumb
et al.'
s estimate and, like that estimate, it reflects the minimum number likely present. Given that Plumb
et al.
(2005b, pp. 19-20) provided a conservative estimate, the actual breeding population is likely larger; however, we have no basis to provide a more accurate estimate.

The BBS data from Wyoming (Sauer 2010a), 1966 through 2009 (−1.2 percent decline annually, 95 percent CI (−5.7 to 3.3)) and 1999 through 2009 (−2.3 percent decline annually, 95 percent CI −13.9 to 4.5)), suggest that both long-term and recent declines in breeding mountain plover numbers in Wyoming may have occurred.

Montana

Primary breeding habitat for mountain plover in Montana is in the north-central portion of the State where mountain plover are highly dependent on black-tailed prairie dog colonies for habitat. Montana Fish, Wildlife and Parks modeled suitable mountain plover habitat in the State. Mapping indicated that the greatest area of highly suitable habitat occurs in Phillips, Blain, Valley, and Fergus Counties with patchy distribution though the central and southeast portions of the State. The total area of suitable habitat estimated was 18.5 million ac (7.5 million ha) (McDonald 2010).

Childers and Dinsmore (2008, p. 706) reported an estimate of 1,028 mountain plover in Phillips and Valley Counties in 2004 (95 percent CI (903 to 1,153)). In 2010, standardized census areas in southwest, central, and northeast Montana produced fewer sightings than previous surveys (1992-2000, 2004); however, McDonald (2010) stated that results were negatively influenced by above average rainfall, increased vegetation height, and limited private land access; therefore, results cannot be relied upon. Other than apparent confirmation of a previously documented decline in the southwest census area (FaunaWest Wildlife Consultants 2004, pp. 4-5), no trends could be inferred from the 2010 survey.

Andres and Stone (2009, p. 8) used the above estimate by Childers and Dinsmore (2008, p. 706) and previous estimates of about 600 mountain plover elsewhere in Montana and provided a Statewide estimate of approximately 1,600 mountain plover. BBS observations of mountain plover on routes in Montana were insufficient to provide estimates of population trend.

New Mexico

Most breeding season reports of mountain plover in New Mexico have come from the northeast and western counties. Sager (1996, pp. 8-9) found 152 presumed breeding adults at 35 sites in 11 counties in northern New Mexico. Marguilies
et al.
(2004, p. 3) estimated 200 mountain plover in Union County alone throughout the summer and located 46 nests. In a limited effort, they also found 22 mountain plover and six nests on public lands in Taos and Colfax Counties.

At BLM's North Unit, Taos County, point counts in 2005 through 2007 estimated 176 mountain plover on 8,400 ac (3,400 ha) of the 50,000-ac (20,000-ha) unit considered to be favorable mountain plover breeding habitat, based on past observation of mountain plover (Hawks Aloft 2007, pp. 9-11). If the entire unit was occupied at the same density, an estimated 1,000 mountain plover might have been present on the North Unit. Manderson (2010, pers. comm.) inspected habitat away from survey routes in 2010, and suggested that, based on habitat quality, 500 or more mountain plover could be present on the entire unit. Mountain plover numbers seen on the same survey routes in 2010 were comparable to those in earlier (2005 through 2007) surveys (Hawks Aloft 2010, p. 13), suggesting this population may be stable.

Goguen (2010, pers. comm.) estimated a minimum of 40 to 50 breeding mountain plover on the Vermejo Ranch, Colfax and Taos Counties. Mountain plover were also recently reported present in El Malpais National Conservation Area, Cibola County (Hawks Aloft 2008, entire).

We found no Statewide breeding surveys or estimates of Statewide breeding populations for mountain plover in New Mexico, other than Andres and Stone's (2009, p. 8) conservative estimate of 500. Given the above data from Union County, the BLM's North Unit in Taos County, the Vermejo Ranch in Colfax and Taos Counties, and likely mountain plover occurrence in several other counties, we believe that at least 1,000 and potentially significantly more mountain plover breed in New Mexico.

BBS data from New Mexico (Sauer 2010a), 1966 through 2009 (−5.0 percent decline annually, 95 percent CI (−8.6 to −1.2)) and 1999 through 2009 (−4.8 decline annually, 95 percent CI (−12.1 to 2.7)), demonstrate a long-term decline and also suggest a short-term decline in breeding mountain plover numbers in New Mexico. New Mexico is the only State for which the long-term BBS trend statistically differs from zero.

Nebraska

In our December 5, 2002, proposal to list the mountain plover we estimated 200 mountain plover in Nebraska (67 FR 72399). Recent studies attempted to identify the extent of breeding distribution and population size in Nebraska (Bly
et al.
2008, entire). Most nests were found on agricultural fields in Kimball County, in extreme southwestern Nebraska, but mountain plover were also found in nearby Cheyenne and Blain Counties. The minimum breeding population was estimated to be 80 adults in 2007, based on nests found, and the total estimate of breeding birds ranged upward to 360 (Bly
et al.
2008, p. 127). Van der Burg
et al.
(2010, pp. 50-53) reported on monitoring in the same three counties (Kimball, Cheyenne, and Blain) in southwestern Nebraska and estimated that mountain plover breeding numbers of 1,650, 1,617, and 1,558 over 3 years of the study (2005, 2006, and 2007, respectively). The authors attributed past low estimates in Nebraska to: (1) Low detection probabilities; (2) clumped spatial distribution of mountain plover, which their estimation methodology corrected for; and (3) “chronic undersampling.” Given the above estimates from Van der Burg
et al.
(2010, pp. 50-53), an estimate by Andres and Stone (2009, p. 8) of 500 breeding mountain plover in Nebraska appears low.

Nebraska is the only State that has regulatory mechanisms in place to conserve the mountain plover and its habitat, which likely protect relatively few individuals. The Nebraska Game and Parks Commission lists the mountain plover as a “threatened” species. Listing of endangered and threatened species identifies those animals and plants whose continued existence in Nebraska is in jeopardy. Efforts can then be made to restore the species or to prevent extirpation or extinction. Once a species is listed, a State law, titled the Nebraska Nongame and Endangered Species Conservation Act, automatically prohibits take, exportation, and possession, and imposes severe penalties on violators (Nebraska Game and Parks Commission

2011). Proposed projects that would be authorized, funded, or carried out by Nebraska State agencies are reviewed as part of a mandatory consultation process designed to prevent a State action from jeopardizing the existence of an endangered or threatened species. Recovery plans for endangered or threatened species are developed; these recovery plans identify, describe, and schedule the actions necessary to restore populations of these animals and plants to a more secure status. Given that most mountain plover in Nebraska occur on private agricultural lands, there are not many State projects that are reviewed under the law. It is generally implemented only 4 or 5 times per year, primarily on transportation, transmission, and energy development projects (Lackey 2011, pers. comm.). While this law may provide protection for some individual mountain plover in Nebraska, we believe that it would only have minimal positive effects on the entire population in Nebraska, or on the rangewide population.

Oklahoma

Recent studies to determine the breeding distribution and population size in Oklahoma detected mountain plover in Cimarron and Texas Counties in the Oklahoma panhandle, mostly on fallow or barren agricultural fields (McConnell
et al.
2009, pp. 30-33). Randomized point counts were used to derive a Statewide population estimate of 68 to 91 birds (McConnell
et al.
2009, pp. 32-33). Andres and Stone (2009, p. 8) estimated 200 mountain plover breeding in Oklahoma. Given results of McConnell
et al.
(2009, pp. 32-33), we believe that Andres and Stone's (2009, p. 8) estimate may be slightly high. The range of the mountain plover in Oklahoma was described as stable over the past 100 years, with the suggestion that populations may have changed little (Hatcher 2010).

Kansas

The Kansas Department of Wildlife and Parks (2005) stated that mountain plover breed only on dry upland in the shortgrass prairie of western Kansas. While conversion to agriculture has left little native breeding habitat, Cable and Seltman (2010, pp. 50-51) reported mountain plover are an uncommon but regular breeding species in western Kansas and that they also use idle cropland. Morton County may also serve as a staging area for migration in late summer (Cable and Seltman 2010, p. 51). Andres and Stone (2009, p. 8) estimated 200 breeding mountain plover in Kansas. No comprehensive surveys of breeding mountain plover in Kansas have been attempted; however, given their apparent use of both prairie and cropland, and a substantial population in nearby Colorado, the estimate may be appropriate.

Texas

The mountain plover likely breeds in Texas, but there are no confirmed reports of breeding since 1993 (Andres and Stone 2009, p. 16). Holliday (2010) described breeding season sight reports of mountain plover from the Texas Panhandle near known Oklahoma breeding sites. Holliday (2004) also mapped potential breeding habitat, much of it on private land that has not been surveyed. Andres and Stone (2010) did not provide an estimate of breeding mountain plover in Texas. We believe that at least minimal numbers of mountain plover breed in Texas.

Arizona

The only known mountain plover nesting in Arizona is in Apache County in east-central portion of the State, with at maximum perhaps a dozen breeding birds (Gardner 2010, pers. comm.). Breeding has occurred on grasslands where cattle were concentrated and at Gunnison prairie dog (
C. gunnisoni
) colonies (Corman 2005, pp. 591-591; Gardner 2010). However, hundreds of square miles of potential breeding habitat in northern and western Arizona have never been surveyed, and there are reports of potential breeding mountain plover on Tribal lands in Navajo County (Corman 2005, pp. 591-591; Gardner 2010, pers. comm.). Andres and Stone (2009, p. 8) estimated 100 breeding mountain plover in Arizona. This estimate acknowledges potential for a more substantial breeding population than limited observations have documented.

Utah

The mountain plover has been a historically rare breeder in shrub-steppe habitat in the Uinta Basin of northeastern Utah. Manning and White (2001, p. 225) described a small breeding population that averaged about 15 adults yearly. Mountain plover breeding in the area subsequently declined, and no birds have been found during surveys of the area since 2003 (Maxfield 2010, pers. comm.). Andres and Stone (2009, p. 8) estimated fewer than 50 breeding mountain plover in Utah. Based on no recent records of breeding mountain plover, this estimate may be optimistic.

North Dakota and South Dakota

The mountain plover once bred in these States, with higher numbers present in South Dakota, but there are no recent breeding records in either North Dakota or South Dakota (North Dakota Game and Fish Department 2010; South Dakota Game, Fish and Parks 2010).

Canada

A review of breeding records for Canada (Knapton
et al.
2006, p. 33) concluded that the mountain plover is a peripheral species in Canada with no evidence that it was ever a common or regular breeder. The first breeding record was documented in 1979 and the most recent in 2007 (Knapton
et al.
2006, pp. 32-33; Holroyd 2010, pers. comm.). Most sightings and breeding records come from extreme southeastern Alberta, with at least one incidence of confirmed breeding in Saskatchewan. Holroyd (2010, pers. comm.) provided updated records of sightings through 2009, mostly from Alberta. Andres and Stone (2009, p. 8) estimated fewer than 100 mountain plover breeding in Canada. We are not aware of any attempts to systematically survey all potential breeding areas in the Canadian range. However, given the low number and limited distribution of reported recent sightings (Holroyd 2010, pers. comm.), we believe that actual breeding numbers are fewer than 100.

Mexico

Breeding records of mountain plover in Mexico have been documented in southeastern Coahuila and Nuevo Leon, following a history of breeding season observations in Mexican prairie dog colonies (Desmond and Chavez-Ramirez 2002 entire; Gonzalez-Rojas 2006, pp. 81-84). Nesting is suspected in San Luis Potosi, 130 mi (200 km) south of the above records (Luevano
et al.
2010, p. 123).

The extent of mountain plover breeding in Mexico is largely unknown. Andres and Stone (2009, pp. 8, 15) estimated fewer than 300 mountain plover breeding in Mexico (fewer than: 50 in Chihuahua, 100 in Cohuila, 100 in Nuevo Leon, and 50 in San Luis Potosi), but suspect that if there are major concentrations of breeding mountain plover not yet discovered anywhere in their range, they are likely in Mexico. The estimate of fewer than 300 birds is at best a guess, but is appropriately conservative given the lack of knowledge regarding breeding mountain plover occurrence and distribution in Mexico.

In summary, we believe that the rangewide breeding population of mountain plover likely exceeds 20,000, with largest populations in Colorado, conservatively 11,000; Wyoming,

conservatively 3,400; Montana 1,600; Nebraska 1,600; New Mexico, at least 1,000 and potentially many more; and smaller populations elsewhere (Kansas, Oklahoma, Texas, Utah, Canada, and Mexico).

Wintering Range

California

Mountain plover are found from north-central California to the Mexico border, mostly from September to mid-March, with peak numbers from December through February (Knopf and Wunder 2006; Hunting and Edson 2008, p. 181). Mountain plover were historically common on the coastal plain in southern California (coastal prairie, alkaline flats, agricultural fields) before being displaced by human development (Hunting and Edson 2008, p. 182; Wunder and Knopf 2003, p. 78). Historically, much of the mountain plover habitat in the Central Valley grasslands was lost following the decline of grazing elk (
Cervus canadensis
), pronghorn antelope, burrowing kangaroo rats, ground squirrels (
Spermophilus
spp.), and other mammals. The combined activities of these herbivores maintained suitable habitat conditions for mountain plover, conditions closely resembling habitat characteristics found on breeding habitats (Knopf and Rupert 1995, p. 750). Farther south in California, desert scrub in the Imperial Valley was converted to agriculture beginning in the 1940s, creating important wintering habitat for the mountain plover. See Hunting and Edson (2008, p. 181) for details of the mountain plover's historical range and abundance in California.

Mountain plover currently occur in the greatest numbers in two general areas in California: (1) The western Central Valley from southern Colusa and Yolo Counties in the north to Kern County in the south (especially the western San Joaquin Valley, the name by which the southern Central Valley is known); and (2) the Imperial Valley in Imperial County (Hunting and Edson 2008, p. 182). The Carrizo Plain, separated from the San Joaquin Valley by the Temblor Range, and the Panoche Valley are also regularly occupied wintering areas.

Populations and trends in the Central Valley are difficult to determine due to the abundance of potential habitat, flock movements, and lack of systematic surveys (Knopf and Rupert 1995, p. 749; Edson and Hunting 1999, p. 17). In our December 5, 2002, proposal to list the mountain plover (67 FR 72396), we included Edson and Hunting's 1999 (p. 27) comment that mountain plover were “rare and local, exceedingly rare, or accidental” within individual counties in the San Joaquin Valley. Wunder and Knopf (2003, p. 78) suggested that, as a result of habitat loss, many mountain plover had shifted from the Central Valley to the Imperial Valley. Hunting and Edson (2008, p. 182) considered reports of 200 to 300 birds in the San Joaquin Valley in winter of 2004-2005, 100 to 200 in Madera County in 2005-2006, 645 in Tulare County in December 2005, and about 300 in western Kings County in January 2006 to be “exceptional.” They also found noteworthy a survey total of 381 mountain plover at the Carrizo Plain in 2006 (Hunting and Edson 2008, p. 182). However, recent reports from the Central Valley also include 645 birds in Madera County in 2006 (McCaski and Garrett 2006, p. 283), 426 in Tulare County in 2007 (McCaski and Garrett 2007, p. 326), 230 in San Joaquin County in 2008 (eBird 2010), 230 in Solano County in 2008 (Central Valley Bird Club 2010), and 223 in Kern County in 2010 (eBird 2010). These reports suggest that significant numbers of mountain plover continue to use widespread areas of the Central Valley annually. Nearby, a recent high count for the Carrizo Plain National Monument was 540 birds in 2009 (Sharum 2010).

In the Imperial Valley, coordinated surveys by 26 observers over 2 days in December 1999 sighted 3,758 mountain plover (Shuford
et al.
2004, p. 7). A survey of mountain plover and their use of cultivated fields in the Imperial Valley of California in 2001 found 4,037 birds (Wunder and Knopf 2003, p. 75), and 3,476 were counted from January 29 through February 6, 2002, by four observers, with the largest flock consisting of 410 birds (AMEC Earth and Environment 2003, p. 9-10). Mountain plover wintering in the Imperial Valley were surveyed in 2003 and 2004, in an attempt to develop a statistically reliable estimate of numbers (Knopf and Wunder 2004, entire). Flocking behavior, mobility, and weather were among factors found to limit the reliability of Imperial Valley estimates (Knopf and Wunder 2004, pp. 9-12). Results of more recent survey estimates in the Imperial Valley include more than 4,500 mountain plover seen in January 2007, approximately 3,000 seen in January 2008, and 827 seen in January 2011 (Kelsey 2011, pers. comm.).

Hunting
et al.
(2001 p. 40), Wunder and Knopf (2003, p. 76), and Hunting and Edson (2008, pp. 181-183) all suggested a significant decline in numbers of mountain plover wintering in California over previous decades. However, we found little evidence available to establish any trend in more recent (2000 to present) wintering numbers in California. The 4,500 mountain plover recorded in the Imperial Valley survey in 2007 (Kelsey 2011, pers. comm.) exceeded mountain plover observed in Statewide surveys from 1994, and 1998 through 2002 (Knopf 1996, p. 12; 68 FR 53083). Most recently, a Statewide survey over 5 days in January 2011 found 1,235 mountain plover (Kelsey 2011, pers. comm.), considerably fewer than found in previous Statewide surveys or recent Imperial Valley surveys. However, it is not apparent how unusually wet weather or other factors contributed to the relatively low number of mountain plover reported in the 2011 survey. California experienced heavy rains in late 2010. December 2010 was the City of Los Angeles' wettest December in 121 years (Southern California Weather Notes 2010).

While California remains the best documented wintering area for the mountain plover, it may winter less than 50 percent of the estimated breeding population (Andres and Stone, p. 9). Knopf (1996, p. 12) estimated 7,000 mountain plover wintering in California and 1,000 to 3,000 wintering elsewhere. In our December 5, 2002, proposed rule to list the mountain plover as threatened, we suggested that few mountain plover wintered in Texas, Arizona, and Mexico (67 FR 72397). We do not know the actual number of mountain plover wintering in California or how the number varies from year to year; however, given no recent evidence that wintering birds in California number more than the 7,000 estimate above (Knopf 1996, p. 12), and our current rangewide estimate of at least 20,000 breeding mountain plover, the previous contention that California winters the majority of all mountain plover appears incorrect. The fewer mountain plover that are wintering in California, on average or in any given winter, the more important that wintering areas outside California become. Unfortunately, we have little information to pinpoint where the majority of mountain plover are wintering.

Texas

Holiday (2010), based on an examination of LandSat (satellite) photos, found that winter records of mountain plover in Texas correlated to the distribution of barren fields and grazed pastures. He also suggested that the northern limit of the wintering range

in Texas is related to the average number of frost-free days, which influences insect availability. Collins (2006, pp. 27-31) summarized mountain plover wintering status in Texas (with much of the compiled records and maps attributable to Holliday). Populations in Hondo County and Medina County areas were described as potentially the largest; Williamson County was characterized as a well-known wintering area, but with populations potentially small compared to other less known areas. Mountain plover were also present around Wharton, Wharton County, and surrounding counties, and the Corpus Christi area was said to potentially hold more mountain plover than reports indicate (Collins 2006, p. 30). Estimates by knowledgeable local birders of wintering mountain plover in the coastal bend area (Nueces and San Patricio Counties) ranged from 200 up to 2,000 to 3,000 birds (Cobb 2009, pers. comm.). The higher numbers were characterized as speculative because the vast amount of available habitat where access is generally limited makes it difficult to draw any conclusions. Andres and Stone (2009, p. 20) provided an estimate of 1,500 mountain plover wintering in Texas, with a note that abundance could be much greater.

Arizona

Approximately 500 mountain plover are believed to winter in agricultural areas of southern and western Arizona, but numbers could be higher because private and Tribal lands are largely unsurveyed (Gardner 2010). Wintering numbers in La Paz and Pinal Counties appeared stable; numbers in Cochise County have significantly decreased in the last 10 to 15 years due to urban expansion; and Yuma County populations were characterized as increasing, with 150 to 300 birds annually (Gardner 2010; Robertson 2010, pp. 3-4). Wintering mountain plover are also reported from the Sulphur Springs Valley in Cochise County (Robertson 2010, p. 2). Andres and Stone (2009, p. 20) provided an estimate of 200 mountain plover wintering in Arizona. Given limited coverage of potential wintering habitat, we consider the above estimate of 500 birds wintering in Arizona the likely minimum.

Nevada

Wintering mountain plover are rarely reported from Nevada, with the most recent reports of up to 17 mountain plover coming from the Armagosa Valley near the Nevada-California border northwest of Las Vegas (eBird 2010).

New Mexico

While some mountain plover likely winter in southern New Mexico, we have no information regarding locations or numbers.

Mexico

Mountain plover's winter distribution in Mexico has not been well studied, but the species is believed to winter from along the United States-Mexico border south into the border States of Baja California, Sonora, Chihuahua, Coahuila, Nuevo Leon, and Tamaulipas, and beyond into Durango, Zacatecas, and San Luis Potosi (Gonzales-Rojas
et al.
2006, p. 81; Knopf and Wuder 2006; Macias-Duarte and Punjabi 2010, p. 4). While the Mexicali Valley, Baja California, located just south of the Imperial Valley, seems to have suitable wintering habitat (200,000 ac (80,000 ha) of farmland), mountain plover have rarely been reported from the area (Macias-Duarte and Punjabi 2010, p. 3).

Two primary concentration areas within the Chihuahuan Desert are believed to be most important for wintering mountain plover: (1) The Janos area in northwestern Chihuahua; and (2) the El Tokio grasslands in southern Coahuila, Nuevo Leon, northeastern Zacatecas, and northern San Luis Potosi (Macias-Duatre and Punjabi 2010, pp. 3-6). Mountain plover are most abundant in the La Soledad region of the El Tokio grasslands. The highest estimated density in Llano de la Soledad (based on data from the winter of 2005-2006) extrapolated over the area suggests that over 2,000 mountain plover were present. Extrapolation from Llano de la Soledad to all prairie dog colonies in the entire El Tokio region provided an estimate of 6,800 mountain plover (Macias-Duarte and Punjabi 2010, p. 6). While this estimate is crude and may be optimistically high, it is not inconsistent with reports of mountain plover flocks in the area totaling 1,600 to 3,500 birds reported by Andres and Stone (2009, p. 18). In the winter of 2005-2006, surveys in Janos estimated 1,435 birds (Salinas 2006, p. 43).

The reported sightings and the estimates presented above are maximums reported, and the numbers can vary greatly from year to year. However, these reports suggest that a substantial number of mountain plover may winter in Mexico. Andres and Stone (2009, p. 20) provided an estimate of 5,000 birds wintering in Mexico. Changes in sampling methodology, annual variability in mountain plover numbers, and the short duration covered by recent systematic surveys prevent any conclusions regarding trends (Macias-Duarte and Punjabi 2010, pp. 5-6, 16, 17).

Summary of Comments and Recommendations

We requested written comments from the public on the proposed listing of the mountain plover during the June 29, 2010, through August 30, 2010, comment period that followed our June 29, 2010, document (75 FR 37353) vacating our September 9, 2003, withdrawal (68 FR 53083) and reinstating our December 5, 2002, proposal to list the mountain plover (67 FR 72396). We contacted appropriate Federal, State, and local agencies; scientific organizations; and other interested parties, and invited them to comment on the proposed rule and supporting documents. Following an initial draft of our final determination we contacted 5 peer reviewers and asked them to review selected portions of the draft.

We received 53 comments in response to the December 5, 2002, proposed rule (67 FR 72396) during the June 29, 2010, to August 30, 2010, comment period. These included comments from 3 Federal entities, 10 States, 3 local governments, 28 organizations or groups (business, industry, environmental), and 8 private parties. WildEarth Guardians also forwarded us 302 similar comments from individuals, and the Colorado Farm Bureau forwarded us 8 similar comments from individuals. We received no requests for public hearings. We also reviewed comments received after our February 16, 1999, and December 5, 2002, proposals to list the mountain plover (64 FR 7587 and 67 FR 72396, respectively) for relevant issues not addressed in more recent comments. All substantive comments have either been incorporated into this final determination or are addressed below.

Peer Review

In accordance with our policy published in the
Federal Register
on July 1, 1994 (59 FR 34270), we solicited expert opinions from five knowledgeable individuals with scientific expertise that included familiarity with the mountain plover, with other shorebird species, the geographic region and habitats in which the mountain plover occurs, and conservation biology principles. We provided reviewers with a partial draft of this document. We received responses from all five of the peer reviewers that we contacted. The peer reviewers generally agreed that we accurately described the species and its habitat requirements; that we provided accurate review and analysis of factors

affecting the species; that our assumptions and definitions of suitable habitat were logical and adequate; that there were few oversights, omissions, or inconsistencies in out draft document; and that we used pertinent literature to support our assumptions and conclusions. One reviewer was generally critical of the synthesis of information regarding threats to mountain plover habitat, especially our assessment of wintering habitat in the Imperial Valley. One reviewer limited comments primarily to population trends. The peer reviewers provided suggestions to improve this final document. Recommended editorial revisions, clarifications, and other changes have been incorporated into the final document as appropriate. We respond to all substantive comments below or through changes to the final document.

Comments From Peer Reviewers

(1)
Comment:
Three reviewers questioned specific details of our range map.

Our Response:
Figure 1, depicting the mountain plover's range, was developed based on those in Knopf and Wunder 2006, and Andres and Stone 2009, with modifications based on our review of recent information. Our map depicts generalized areas believed to support breeding and wintering mountain plover, and does not depict localized areas of presence or absence. We made some revisions to our range map based on reviewer comments.

(2)
Comment:
One reviewer pointed out that while mountain plover are attracted to burned areas on their breeding ground, there is little evidence as to whether such burned areas benefit breeding mountain plover (for example, through higher nest success or fledging success) compared to habitats they may otherwise use.

Our Response:
Reduced vegetative cover resulting from burning appears more attractive to mountain plover than similar habitat left unburned. However, we agree that studies have not documented the specific relationship of burning to successful mountain plover nesting.

(3)
Comment:
One reviewer stated that estimates of annual survival should be considered minimum estimates, because studies do not control for permanent migration of mountain plover (
i.e.,
they assume birds not accounted for have died rather than moved away from the study area).

Our Response:
We agree and have acknowledged this in the text. Studies in Montana have produced the most complete information on juvenile (first year of life) and adult mountain plover annual survival rates, but the extent to which these studies underestimate survival rates due to emigration is not known.

(4)
Comment:
One reviewer asserted that recent literature clearly identified adult survival as a vital importance to productivity and survival of shorebird populations.

Our Response:
We agree. In the limited studies that have estimated adult survival of mountain plover, adult mountain plover survival appears relatively high. The suggestion that management efforts to increase mountain plover populations might best be targeted at increased chick survival (hatching to fledging) result, in part, from data showing relatively low and highly variable survival of mountain plover chicks (see Survival, Lifespan, and Site Fidelity above).

(5)
Comment:
Two reviewers noted that while the mountain plover may have a long lifespan compared to many other shorebirds, some shorebirds do live longer and other bird families, such as seabirds, live much longer.

Our Response:
Mountain plover in the wild have been known to live to over 10 years. We have qualified our description of the mountain plover as a “relatively” long-lived species.

(6)
Comment:
One reviewer suggested that mountain plover fidelity to breeding sites is more regional than site-specific and that differences in habitat across the mountain plover breeding range may influence site fidelity.

Our Response:
Both may be correct. Lack of genetic differentiation found by Oyler-McCance
et al.
(2005, p. 359; 2008, pp. 496-497) suggest that mixing of mountain plover across regions is also occurring.

(7)
Comment:
One reviewer suggested that we discuss spatial and temporal variation in long-term and recent BBS trend data for the mountain plover and cited a long-term (1966 through 2009), negative New Mexico trend as the only statistically significant population trend among the rangewide or Statewide BBS trend estimates we provide.

Our Response:
We have included data pertinent to spatial and temporal (by State and long-term versus short-term) trends in mountain plover populations in this document when available (see Conservation Status and Local Populations above). These statistics are based on fewer data and generally appear less reliable than rangewide trends. The long-term trend estimate in New Mexico is unique among those we cite, in that it reflects a statistically significant indication of at least some decline.

(8)
Comment:
One peer reviewer stated that there is insufficient information about the distribution and status of the mountain plover in Mexico to evaluate whether past, present, or future loss of prairie dogs and the ecosystem they support in Mexico is a significant threat to the mountain plover.

Our Response:
We agree that information on the distribution and status of the mountain plover in Mexico is limited. Based on the information available, past loss of prairie dogs colonies in Mexico has decreased available mountain plover habitat and may have had some adverse impact on the mountain plover. Recent Mexican and international attention to conservation of prairie dogs and grassland complexes in Mexico improves prospects for maintaining existing mountain plover wintering habitat (see
Factor A
below). While future losses of prairie dog colonies in Mexico may occur, we do not believe that associated impacts to mountain plover's habitat present a significant threat to the mountain plover over its wintering range.

(9)
Comment:
One reviewer stated that discussion of habitat loss to land use modification would be greatly improved by including specifics of how these losses fall within the precise breeding and wintering habitats of the mountain plover. Two reviewers contended that the relative threat posed by agricultural conversion (of grasslands) was difficult to assess unless analyzed at a fine spatial scale.

Our Response:
The mountain plover's breeding and wintering ranges extend across a large area and encompass a variety of habitat types. We have addressed habitats supporting the mountain plover, habitat losses, and threats to mountain plover habitat on a rangewide and regional level, and in some cases on a State or local level as well.

(10)
Comment:
One reviewer offered that uncertainties regarding future agricultural practices on private lands emphasized the importance of managing for the mountain plover on State and Federal lands.

Our Response:
A great degree of uncertainty exists regarding future agricultural practices on private lands, but we believe that changes in agriculture are not likely to significantly threaten the mountain plover in the foreseeable future. Across the range of the mountain plover there are currently many initiatives, on both public and private lands, to manage habitat for wildlife including the mountain plover, bird species using similar habitats, and

prairie dogs (see
Factor A
discussion below). The mountain plover has been designated a bird of conservation concern by the Service (2008) and has special conservation status in many States (see Conservation Status and Local Populations above and
Factor A
discussion below). We anticipate and support continued emphasis on mountain plover conservation and management by our Federal and State partners.

(11)
Comment:
One reviewer noted that, without synthesis of exactly what agricultural lands mountain plover require on their wintering areas and how those specific fields are threatened (for example, fallowing of crop fields in California's Imperial Valley), our conclusion that threats impacting only a small portion of agricultural lands would not affect mountain plover was problematic.

Our Response:
In Migration and Wintering Habitat above, we describe wintering habitats favored by the mountain plover. In
Factor A
below we discuss threats that may impact these habitats, including threats to certain crop types favored by the mountain plover. The level of analysis we provide is sufficient to evaluate threats to the mountain plover from changes on agricultural lands that provide wintering habitat and utilizes the best available information we have regarding this topic. Without specific information to suggest otherwise, we conclude that threats would not disproportionately impact those particular fields that presently receive, or in the future would receive, most use by the mountain plover.

(12)
Comment:
One reviewer noted that the Imperial Valley, California, an area supporting significant numbers of wintering mountain plover, is one of the fastest growing areas of the United States.

Our Response:
From 1984 to 2008, urban area in the Imperial Valley increased by 6,000 ac (2,400 ha) (CDC 2010), much of it outside of croplands favored by the wintering mountain plover. About 381,000 ac (154,000 ha) of field crops are present in the Imperial Valley (Imperial Irrigation District (IID) 2009a). We concluded that population growth and urban expansion is having a modest impact on Imperial Valley croplands, but does not rise to the level of a threat to the species (see
Factor A
discussion below).

(13)
Comment:
One reviewer stated that, over the wintering range of the mountain plover, increase in human population, associated land use changes, and reductions in available water for agriculture would impact areas currently used by mountain plover. The reviewer concluded that because there was “lack of suitable habitat to move to,” this would be detrimental to mountain plover.

Our Response:
Human development and changes in agriculture, including changes brought on by future water availability, are likely to impact some of the areas currently used by wintering mountain plover in California, in southern Arizona, and elsewhere in their wintering range. Based on the likely magnitude of such changes and the extensive wintering range of the mountain plover, we conclude that loss of wintering habitat is not likely to be a significant threat to the mountain plover in the foreseeable future (see our discussion in
Factor A
below).

(14)
Comment:
One reviewer questioned whether mountain plover are impacted by pesticides and herbicides used on sod farms where they are often seen during migration or in winter.

Our Response:
We have found no documentation of effects to mountain plover from exposure to pesticides on sod farms. However, in the past, the use of diazinon, an organo-phosphate pesticide, on sod farms may have impacted the mountain plover. In 1988, after documented large die-offs of birds of other species, the U.S. Environmental Protection Agency (EPA) cancelled the registration of diazinon for use on golf courses and sod farms (EPA 2006, p. vii). We have no information regarding significant harm of any bird species since 1988 that is attributable to use of pesticides on sod farms.

(15)
Comment:
One reviewer suggested more discussion on invasive grasses and their impact on mountain plover.

Our Response:
Invasive plants, including nonnative grasses planted as forage for cattle, are widespread across the western United States. Many invasive plants grow to a density or height that can make habitat unsuitable for mountain plover. While perceived by some as a potential threat, the effects of nonnative grasses and invasive plants on the mountain plover have not been well documented. Within the ecosystems it inhabits, the mountain plover is best supported where native or domestic herbivores, fire, dry conditions, soil conditions, or disturbance create low, sparse vegetation. In general, this is true whether the vegetative community consists only of native vegetation or also supports a component of nonnative or invasive plants.

Public Comments

Process Issues

(16)
Comment:
One commenter stated that e-mails, personal communications, and letters that the Service referenced in support of the December 5, 2002, listing proposal (67 FR 72396) do not meet the best information available standard as described in Service policy (59 FR 34271, July 1, 1994).

Our Response:
Our policy, as cited above, requires that we evaluate all scientific and other information available, which includes both published and unpublished materials, in the development of a listing action. We review the information regardless of origin, and determine whether it is reliable, is credible, and represents the best information available regarding the species under review. We document our evaluation of any information we use in making our decision, whether it supports the decision or not.

(17)
Comment:
Commenters believed that our analysis in our February 16, 1999, and December 5, 2002, proposals to list the mountain plover (64 FR 7587 and 67 FR 72396, respectively) used “selective science” to defend our position, while ignoring information contrary to our conclusion.

Our Response:
We base our determinations on review of all pertinent information available. This final determination is further based on substantial new and additional information available since our previous actions.

(18)
Comment:
One commenter stated that in the 1999 and 2002 proposals to list the mountain plover (64 FR 7587 and 67 FR 72396, respectively) the Service did not identify or quantify actual threats, and therefore the Service has not shown that mountain plover have declined or are at risk.

Our Response:
In this final determination, we have evaluated the relative security of the species from present and foreseeable threats across its breeding, migratory, and wintering range. Where available information has allowed, we have identified and quantified actual threats to the mountain plover in this evaluation. While threats, especially future threats, may be difficult to quantify, we evaluate threats based on analysis of the best scientific and commercial information available.

(19)
Comment:
One commenter stated that e-mails and faxes should be accepted as comment on the proposed listing.

Our Response:
Our policy requires submission of written comments through the Internet (via the Federal

eRulemaking Portal at
http://www.regulations.gov
), or by U.S. mail or hand-delivery, and we believe this provides the means for all interested parties to provide comments, information, and recommendations.

(20)
Comment:
Various commenters suggested that there are either more or fewer reasons for listing the mountain plover now compared to 2003 when our proposed listing was withdrawn (68 FR 53083, September 9, 2003).

Our Response:
Our 2003 decision was vacated by the Court and is not relevant to this final determination regarding the mountain plover. We have based our determination on the current status of the mountain plover and current and future threats to the species, based on the best scientific and commercial information available to us at this time.

Issues Regarding Range, Numbers, and Populations Trends

(21)
Comment:
One commenter questioned our emphasis on the PNG in Colorado and Charles M. Russell National Wildlife Refuge (NWR) in Montana in our proposals to list the mountain plover, as relatively few mountain plover breed in either site.

Our Response:
We agree that neither site currently supports a large percentage of the total mountain plover population. Both sites are Federally controlled and have supported mountain plover research and management efforts. The PNG once likely supported the highest density of mountain plover in the species' breeding range. The dramatic loss of this sizable population has relevance to the rangewide population trend and may provide insight to current and future threats to the mountain plover. Charles M. Russell NWR provides management opportunities on a Montana site representative of those where mountain plover is largely dependent on the black-tailed prairie dogs to create desirable habitat conditions.

(22)
Comment:
One commenter stated that breeding habitat on public and private lands in the mountain plover's range has not been adequately surveyed and suggested that additional surveys will consistently find more mountain plover.

Our Response:
Knowledge of mountain plover populations varies greatly across the breeding range. Surveys vary in methodology and scope. In some cases, lack of access to conduct surveys on private lands limits the accuracy of population estimates. Based on information available since 2002, estimates of mountain plover breeding numbers in certain States and throughout the range have been modified. Former rangewide population estimates were based on surveys of mountain plover in California, where the vast majority of birds were thought to winter. Our current rangewide population estimate is based on minimum breeding range population estimates. However, no estimate currently exists that provides a precise estimate of rangewide numbers.

(23)
Comment:
One commenter dismissed population estimates as “just a guess.”

Our Response:
We believe that some structured studies on the breeding range have produced population estimates that approximate the actual numbers of mountain plover that are present. In other cases, estimates may be limited to the minimum number of individuals known, or may suggest the likely population size based on limited data. While we summarize population estimates and seek to understand population trends, numbers alone are not the basis for listing determinations under the Act. Listing determinations are based on whether there are threats present or likely to occur that would result in the species being in danger of extinction or likely to become so within the foreseeable future.

(24)
Comment:
Several commenters cited increased rangewide population estimates as a reason why the mountain plover does not merit listing. One commenter cited the recent status change by the IUCN (downlisting from “vulnerable” to “nearly threatened”) as evidence of reduced threat to the species.

Our Response:
While greater abundance suggests less vulnerability, we have no basis to suggest that the increased estimate of mountain plover numbers reflects an actual, rangewide increase. The number of individuals of a species present is only one factor considered when assessing vulnerability to extinction. Current and future threats may be of greater significance. Downlisting by the IUCN was based on revised population estimates alone, and not on changed interpretation of threats present.

(25)
Comment:
One commenter noted that all wintering areas in the United States and Mexico have not been located and opined that further searching is likely to yield more wintering sites.

Our Response:
While more information overall has been gathered since our 2002 proposal (67 FR 72396, December 5, 2002), much is still unknown regarding wintering habitat. Rangewide breeding population estimates and wintering estimates from California suggest that a substantial percentage of mountain plover winter elsewhere. Because the large flock sizes observed in California are not regularly encountered elsewhere, mountain plover numbers may occur at lower densities in other parts of their wintering range.

(26)
Comment:
One commenter stated that the former estimate of 20,000 breeding mountain plover at the PNG in the 1970s may have been off by an order of magnitude.

Our Response:
While the actual number present in the 1970s is unknown, it is well established that mountain plover populations on the PNG have greatly decreased since that time, with relatively few breeding mountain plover present since the mid-1990s.

(27)
Comment:
One commenter questioned our estimates of up to 10,000 mountain plover at Kern NWR in California during the 1960s.

Our Response:
Many mountain plover used Kern NWR in winter during the 1960s, but the 10,000 estimate is by far the largest recorded (Engler 1992). We believe estimates at Kern NWR approximate mountain plover numbers attracted to the refuge by favorable habitat conditions previously present.

(28)
Comment:
Multiple commenters mentioned continued, significant declines across the breeding and wintering range of the mountain plover, as cited by researchers, as indicative of the species' imperiled status.

Our Response:
Documentation of historical range contraction and apparent decline in mountain plover populations is reflected in long-term BBS and CBC trends. Despite more intensive study in recent years, it is not clear if, or to what extent, any declines in mountain plover populations continue. See our discussion of Population Size and Trends above.

(29)
Comment:
A few commenters stated that BBS and CBC data and trends regarding mountain plover are unreliable. Others state that these data are a reason for concern.

Our Response:
The BBS is the best available long-term trend information for the mountain plover on its breeding range. It is an imprecise indicator of mountain plover population trends. These data appear to confirm a decline over the period 1966 through 2009, but results suggest that the rate of any continued (1999 through 2009) decline has moderated. The CBC data are more restricted in geographic scope than are the BBS data, but these data also suggest a long-term decline. Few CBC count circles regularly report mountain plover, and numbers are highly variable, likely reflecting mobility of wintering flocks.

See our discussion of Population Size and Trends above.

(30)
Comment:
We received a comment that insufficient data are available to predict any trend toward extinction.

Our Response:
We agree that current trend data are limited and that the ability to project future population trends is difficult. However, we have reviewed the best population and trend data available as part of our analysis of the mountain plover's status. In making our final listing determination, we not only looked at population trends, but we have also evaluated the best available information on current and future threats to the species.

(31)
Comment:
One commenter suggested that population trends at the PNG, where the birds have been closely studied, are indicative of the overall population trend for the mountain plover.

Our Response:
Knopf (2008, p. 61) summarized mountain plover studies on the PNG in Weld County, Colorado, and suggested reasons for that population's former abundance and more recent decline, including long-term changes in habitat since abandonment of agricultural fields following the “Dust Bowl” of the 1930s. We believe that this represents a unique history because long-term BBS data (Sauer 2010a) suggest a relatively stable population in Colorado despite the dramatic drop in numbers on the PNG. In 2008, Knopf expressed the opinion that similar numbers of mountain plover were breeding in Weld County as in 1990, just not on the PNG (Knopf 2008, p. 54). We have no scientific information that would point to the precipitous decline in mountain plover historically at the PNG as indicative of the overall mountain plover population trend.

(32)
Comment:
One commenter suggested that mountain plover numbers are dynamic, and that their current abundance is within the range of normal fluctuation due to annual variation in weather patterns.

Our Response:
Breeding numbers and nest success can vary locally based on a number of factors including weather. However, the historical reduction in rangewide mountain plover numbers seems well substantiated. Interpretation of recent trends is made more difficult by short-term variability in population numbers that may reflect annual weather variation. The effect of all factors, natural and human-caused, that may contribute to the survival of the mountain plover is considered in this determination, including variation in weather patterns and longer-term changes in climate.

Species Vulnerability

(33)
Comment:
One commenter referenced the mountain plover's relatively short lifespan as contributing to the vulnerability of populations to extirpation if one or more years of unfavorable habitat on their breeding grounds prevent successful nesting.

Our Response:
As discussed above in our discussion of Population Size and Trends, and under
Factor E
below, our former conclusion that the lifespan of mountain plover contributed to its vulnerability has been refuted based on more recent information. The mountain plover is now considered a relatively long-lived species, with one individual documented living for 10 years (Dinsmore 2008, p. 52). We do not believe that mountain plover lifespan substantially influences the vulnerability of mountain plover to extinction.

(34)
Comment:
One commenter stated that breeding mountain plover populations are often discontinuous, in part because of habitat fragmentation, and stated that local, isolated mountain plover populations have an increased vulnerability to random natural and human-caused events.

Our Response:
It is generally true that small and isolated populations are less secure than larger populations. While the mountain plover is a migratory, highly mobile species, it generally returns to the same breeding sites, which isolates local populations to a degree. Small mountain plover populations are vulnerable to “blinking out” if events destroy or degrade habitat. This vulnerability may be offset by the species' ability to colonize new habitat as it becomes available. Recent studies describe mountain plover dispersal from natal sites or former breeding sites, and suggest that the mountain plover has been able to disperse and exploit habitat nearby if former habitat is destroyed.

Prairie Dog Issues

(35)
Comment:
We received numerous comments regarding mountain plover and prairie dogs. They included comments regarding the mountain plover's dependence on prairie dogs, and the distribution, abundance, and trends in prairie dog populations. One commenter contended that if the black-tailed prairie dog does not merit listing, then the mountain plover does not either.

Our Response:
It is well established that in parts of its range, Montana in particular, the mountain plover is largely dependent during breeding on the habitat that prairie dogs create and maintain. Elsewhere, mountain plover also breed in a variety of habitats, including prairie, semi-desert, and cropland. See our discussion regarding the status and threats to the black-tailed prairie dog and potential effect on the mountain plover in
Factor A
below. We recently determined that the black-tailed prairie dog does not warrant listing under the Act (74 FR 63343, December 3, 2009), but it does not follow that this would automatically lead to a similar conclusion for the mountain plover since the species could be subject to a variety of threats unrelated to the status of prairie dogs.

(36)
Comment:
We received a comment that the Service in 1999 and 2002 underestimated the presence of prairie dogs and therefore their habitat and the number of mountain plover that prairie dog colonies supported.

Our Response:
Our current analysis includes information developed since 2002. Under
Factor A
below, we discuss current estimates of prairie dog abundance and implications of prairie dog numbers to mountain plover.

(37)
Comment:
Some commenters stated that black-tailed prairie dogs lack protection, are often poisoned or shot, and are often affected by sylvatic plague; therefore, prairie dog colonies and the mountain plover they support remain vulnerable.

Our Response:
We agree that there are few protections for the black-tailed prairie dog. However, despite the above factors, the black-tailed prairie dog has increased in number throughout all States in its range in the United States since the 1960s. In the United States, we do not foresee any significant decreases in black-tailed prairie dog populations or the habitats they create. On December 3, 2009, the Service published a 12-month finding that the black-tailed prairie dog is not threatened with extinction and is not likely to become so in the foreseeable future (74 FR 63343). In Mexico, both the black-tailed prairie dog and the Mexican prairie dog continue to be reduced in number and distribution, and this likely impacts mountain plover habitat. See our discussion under
Factor A
below.

(38)
Comment:
Other commenters cited conservation efforts that target prairie dogs, as well as efforts to conserve greater sage-grouse (
Centrocercus urophasianus
), lesser prairie-chicken (
Tympanuchus pallidicinctus
), and black-footed ferret (
Mustela nigripes
), and concluded that these existing efforts make mountain plover conservation efforts unnecessary.

Our Response:
Efforts to conserve these species are in response to declines in numbers and threats to their future existence. While the mountain plover

will benefit from conservation of prairie dogs, some other species require habitats unlike those favored by the mountain plover. To the extent that mountain plover benefit from conservation efforts for other species, these are addressed under
Factor A,
below.

(39)
Comment:
One commenter contended that the presence of prairie dogs was only one of several factors that create mountain plover breeding habitat and that soil type, soil moisture, cattle grazing, fire, and incidence of drought all play a role in supplying suitable mountain plover breeding habitat.

Our Response:
While the literature on the mountain plover is replete with the association of mountain plover and prairie dog colonies, we agree that other factors, singly or in combination, can shape mountain plover breeding habitat, and we have taken this into consideration in this final listing determination.

Grassland Conversion and Agricultural Issues

(40)
Comment:
Multiple commenters state that grassland conversion to cropland is a significant threat.

Our Response:
While grassland conversion contributed to past contraction in the mountain plover's range and reduction of the mountain plover's numbers, much of this took place on the eastern Great Plains where conversion to crops such as corn and soybeans was feasible. The rate of grassland conversion is now much reduced. We do not believe that the current or anticipated future conversion of grasslands to other uses is a significant threat. Dryland agriculture, found in the southern portions of the mountain plover's breeding range, supports significant numbers of breeding mountain plover. The extent to which the use of dryland agricultural habitat is beneficial to the mountain plover is largely undetermined. See our discussion under
Factor A
below.

(41)
Comment:
One commenter contended that current farming practices benefit breeding mountain plover, that mountain plover are an adaptable species that have shifted from grasslands to cultivated lands on both their breeding and wintering areas, and that cultivated lands are now the most important habitat for the mountain plover. Other commenters raised the question of whether the choice to nest in cropland is detrimental to mountain plover.

Our Response:
Research findings from Colorado present a complex picture. Hatching success on some croplands is similar to that found on grasslands with or without prairie dogs. Chick survival appears to be lower on crop fields, but results of some studies differ, perhaps depending on variables such as annual weather conditions and site-specific levels of predation. The influence of the agricultural landscape on mountain plover recruitment has not been fully determined. Wintering mountain plover favor crop fields at times, but habitat preference seems to vary greatly by region. Mountain plover use of crop fields in winter may reflect the loss of preferred native habitats.

(42)
Comment:
One commenter stated that farming practices on the prairie have not changed in 50 years and questioned why they could suddenly be a threat.

Our Response:
Dryland farming practices in eastern Colorado and adjacent States have remained relatively stable, although market factors may favor one crop over another. Historically, conversion of prairies to crop fields likely contributed to the decline of mountain plover, especially in the eastern portion of its range. Farm operations can directly impact nesting, but the current relationship between dryland crop fields and breeding mountain plover is complex. However, the best available information indicates that current agricultural practices have remained largely unchanged in recent years and have not been shown to pose a threat to the mountain plover (see
Factor A
discussion below).

(43)
Comment:
Several commenters stated that the Conservation Reserve Program is beneficial to the mountain plover, while other commenters thought the program was detrimental to the mountain plover.

Our Response:
The U.S. Department of Agriculture (USDA) administers the Conservation Reserve Program, which allows producers to retire agricultural lands for a 10-year period, thereby benefitting wildlife and other resources. Most of these lands are planted with nonnative grasses that support other wildlife species but often do not create mountain plover habitat. The program likely has little effect on overall mountain plover habitat because a relatively small portion of agricultural fields are retired at any one time and retired lands provide minimal benefit to mountain plover.

(44)
Comment:
Commenters expressed concern that anticipated human population growth in South Park, Park County, Colorado, and the fragmentation of existing habitat there, will impact a significant mountain plover population.

Our Response:
We agree that buildout of private lands in South Park would adversely affect the mountain plover breeding population that is currently present. However, based on information from Park County, population growth is much slower than once predicted, and we do not anticipate substantial human development will occur in the area in the foreseeable future. See our discussion under
Factor A
below.

Livestock/Grazing/Range Management

(45)
Comment:
One commenter stated that range management has contributed to the past decline of mountain plover and is a current threat, as practices vary little from those used previously.

Our Response:
Range management is often designed to maximize forage and diminish excessive disturbance to grass and soil. Such management, when employed, does not benefit the mountain plover. However, we do not see range management as representing a current or future threat to the mountain plover, as there is no information to suggest that current range management practices and the habitat conditions now present are likely to change substantially in the future.

(46)
Comment:
One commenter cited recommendations by Knopf and Wunder (2006) to prioritize research regarding varied livestock grazing practices and their effects on mountain plover.

Our Response:
Research is ongoing as to how range management affects mountain plover and a variety of other grassland species. We have a basic understanding of how livestock grazing can enhance mountain plover habitat (Dechant
et al.
2003, entire).

(47)
Comment:
Commenters cited the decline in sheep (
Ovis aries
) numbers in the mountain plover's breeding range as detrimental to mountain plover.

Our Response:
Sheep grazing helps maintain low vegetation structure favored by the mountain plover. The U.S. sheep industry has been in decline since the 1940s. Past declines in sheep may have contributed to losses in mountain plover breeding habitat. The future of the sheep industry in the United States is difficult to predict. See our discussion under
Factor A
below.

(48)
Comment:
One commenter stated that cattle do not replace the role of bison in the ecosystem, and that the role of cattle grazing as it relates to insect availability has not been adequately evaluated.

Our Response:
The historical loss of bison resulted in a number of changes to the prairie ecosystem. Current mountain plover numbers and distribution, and our evaluation of threats to the species, are based on an ecosystem largely devoid of bison.

Insect numbers and availability to mountain plover under various grazing regimes may be worthy of investigation.

Mineral Extraction/Energy Development

(49)
Comment:
We received many comments on the threat to the mountain plover posed by oil and gas field development, and wind energy development. Commenters stated that effects of energy development on the mountain plover are largely unknown and that the mountain plover's response to oil, gas, and wind energy development should be investigated.

Our Response:
We discuss the potential impact of energy development on mountain plover under
Factor A
below. Wells, turbines, roadways, and related development constitute potential threats. While far from definitive, recent studies suggest mountain plover may be little affected by oil and gas development. Thus far, we have no data on the effect of wind energy development on wintering mountain plover.

(50)
Comment:
One commenter recounted the history of mountain plover presence at the Antelope Coal Mine in Wyoming and suggested that mountain plover are tolerant of both ground disturbance and nearby industrial activity.

Our Response:
We agree that results of monitoring at this site confirm the mountain plover's preference for open ground created by disturbance and a general tolerance of human activity. While mining activity displaces mountain plover, reclamation following mining may restore habitat.

(51)
Comment:
One commenter described new wind energy projects under development in southern Texas areas where mountain plover winter and thought that the species would be affected by the presence of turbines.

Our Response:
As stated earlier, thus far, we have no data on the effect of wind energy development on wintering mountain plover. The response of mountain plover to turbines on their breeding areas (which indicates some degree of tolerance) may not provide insight into how flocks respond in winter.

(52)
Comment:
One commenter noted conservation efforts to limit energy development on State-designated greater sage-grouse Core Breeding Areas in Wyoming, which include 36 percent of likely mountain plover breeding habitat in the State. The commenter suggested that this will provide a significant measure of protection for the mountain plover.

Our Response:
While limitations on energy development in these areas may reduce potential for any associated adverse impacts on the mountain plover, there is uncertainty as to whether such measures will persist into the future. Designated greater sage-grouse Core Breeding Areas are broad and encompass habitats that support mountain plover, but from a habitat perspective, the needs of the two species differ. Measures to manage for the greater sage-grouse may not benefit the mountain plover.

(53)
Comment:
One commenter suggested that the Service should base its analysis of the energy development threats on what is known regarding the impact of roads, habitat conversion, and fragmentation. Others raised the issue of roads and structures resulting in increases in mammalian and avian predators of mountain plover, which in turn could lead to higher mortality of mountain plover chicks and adults.

Our Response:
In general, while some other species have been shown to be adversely impacted by energy development, we have little evidence of similar impacts on the mountain plover. Changes in habitat brought on by energy development, including the potential that roads and structures may facilitate increased predation on the mountain plover, are addressed under
Factor A
and
Factor C
below. Some adverse impacts are likely, but there may also be offsetting benefits resulting from the increase in bare ground preferred by the mountain plover.

(54)
Comment:
One commenter noted that the Western Governors Association, States, and the wind industry have been addressing concerns regarding construction of wind energy projects on sensitive wildlife areas.

Our Response:
The Service is engaged with the wind industry and other partners on issues regarding a range of wildlife including the endangered whooping crane (
Grus americana
), and candidates including the greater sage-grouse, lesser prairie chicken, and Sprague's pipit (
Anthus spragueii
), as well as the mountain plover. We anticipate that current emphasis on renewable energy projects will be accompanied by cooperative initiatives to minimize impacts to species of concern.

(55)
Comment:
One commenter was concerned that mountain plover populations could decrease significantly while studies on impacts from energy development were ongoing and that precautionary measures should be enacted to preclude potential impacts.

Our Response:
The USFS and BLM have designated the mountain plover a sensitive species within portions of the range (see discussion under
Factor D
below). These agencies address potential impacts to the species when reviewing energy development. However, we will continue to work with these and other Federal agencies, States, and other partners to monitor the status of the mountain plover.

Wintering Habitat

(56)
Comment:
We received many comments on actual or potential loss of wintering habitat in California and how this could affect rangewide populations of mountain plover. Commenters stated that the historical and ongoing conversion of grasslands in California is a threat to the mountain plover. Some commenters cited Andres and Stone (2009, p. 1), describing crucial threats facing the mountain plover, including “

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2011-11056. Public record. Not legal advice.