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CFR Citation: 50 CFR Part 17

RIN ID: RIN 1018-AI45

NOTICE: PROPOSED RULES

ACTION: Endangered and threatened species:

DOCUMENT ACTION: Proposed rule; withdrawal.

SUBJECT CATEGORY: Endangered and Threatened Wildlife and Plants; Withdrawal of the Proposed Rule to List the Mountain Plover as Threatened

DOCUMENT SUMMARY: We, the Fish and Wildlife Service (Service), determine that the action of listing the mountain plover (Charadrius montanus) as threatened, pursuant to the Endangered Species Act of 1973, as amended (Act), is not warranted, and we consequently withdraw our proposed rule and our proposed special rule. We make this determination because threats to the species as identified in the proposed rule are not as significant as earlier believed, and current 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.

SUMMARY: Mountain plover; withdrawn,

SUPPLEMENTAL INFORMATION

The mountain plover (Charadrius montanus) is a small bird averaging 21 centimeters (8 inches) in body length and is similar in size and appearance to a killdeer (Charadrius vociferus). It is light brown above with a lighter colored breast, but lacks the contrasting dark breastbelt common to most other plovers, including the killdeer. Mountain plovers are insectivores; beetles, grasshoppers, crickets, and ants are its principal food items (Stoner 1941, Baldwin 1971, Rosenberg et al. 1991, Knopf 1998).

The mountain plover is associated with shortgrass and shrubsteppe landscapes throughout its breeding and wintering range. Historically, on the breeding range, the plover occurred on nearly denuded prairie dog colonies (Knowles et al. 1982, OlsonEdge and Edge 1987) and in areas of major bison concentrations where vegetation was clipped short (Knopf 1997). Currently, the mountain plover also is found on human made landscapes (e.g., sod farms and cultivated fields) that may mimic their natural habitat associations, and on other sites with little vegetative cover (e.g., alkali flats). As mountain plovers are usually associated with sites that are modified by grazing and digging mammals (kangaroo rat (Dipodomys sp.) precincts and California ground squirrel (Spermophilus beecheyi) colonies on wintering grounds in California, as well as prairie dog colonies on the breeding grounds), Knopf and Miller (1994) suggested classifying the mountain plover as a species more closely associated with disturbed prairie sites, rather than pristine prairie landscapes.

Mountain plovers nest in the Rocky Mountain and Great Plains States from Montana south to Nuevo Leon, Mexico. Most mountain plovers breed in Montana, Wyoming, and Colorado, with substantially fewer breeding birds occurring in Arizona, Kansas, Nebraska, New Mexico, Oklahoma, Texas, and Utah. Breeding was confirmed in 1999 in Mexico on a Mexican prairie dog (Cynomys mexicanus) colony in the State of Nuevo Leon (Desmond and Ramirez 2002). Nesting habitat in Canada is restricted to southeastern Alberta and southwestern Saskatchewan. Nesting has not been documented in Canada since 1990.

Breeding adults, nests, and chicks have been observed on cultivated lands in Colorado, Kansas, Nebraska, Oklahoma, and Wyoming (Shackford and Leslie 1995; Shackford et al. 1999; V. Dreitz, Colorado Natural Heritage Program, in litt. 2003; Young and Good 2000). The majority of mountain plovers winter in California, where they are found mostly on cultivated fields. However, they also can be found on grasslands or landscapes resembling grasslands (Edson and Hunting 1999, Knopf and Rupert 1995, Wunder and Knopf 2003). Wintering mountain plovers also are reported in Arizona, Texas, and Mexico, but fewer have been documented at these locations than in California.

Historically, the mountain plover has been found in a variety of habitats during winter, including grasslands and agricultural fields in California (Belding 1879 in Grinnell et al. 1918; Tyler 1916; Grinnell et al. 1918; Preston 1981 in Moore et al. 1990; Werschkull et al. 1984 in Moore et al. 1990). Irrigated farmlandsburned Bermuda grass fields and grazed alfalfa fieldsin the Imperial Valley of California, where desert scrub has been converted to agriculture within the past 100 years, have become the predominant winter habitat for mountain plovers (Wunder and Knopf 2003, AMEC Earth and Environmental 2003). There, plovers move onto fields for short periods following harvest, especially where the fields are turned over, burned, or grazed by sheep. Insect availability, furrow depth, size of dirt clods, and the vegetation of contiguous land parcels are believed to influence the suitability of individual cultivated fields (E. MarquisBrong, in litt. 1999). Therefore, while cultivated lands are abundant throughout the Central and Imperial Valleys, not all of them are suitable wintering habitat. Because annual climatic changes in the Central Valley can greatly influence vegetative structure within a given year, mountain plover observations at traditionally occupied sites decline in years when abundant rainfall causes vegetation to become too tall (E. MarquisBrong, Bureau of Land Management (BLM), in litt. 1999).

Historically, breeding mountain plovers were reported as locally rare to abundant, and widely distributed in the Great Plains region from Canada south
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to Texas (Coues 1878, Knight 1902, McCafferty 1930, Bailey and Neidrach 1965). Knopf (1996b) estimated the North American mountain plover population to be between 8,000 to 10,000 birds. His estimate is based on a 1994 count of mountain plovers on their winter habitat in California. Applying the same assumptions using the more recent 1998 2002 winter counts ranging from 1,372 to 4,037 individuals would yield an estimate ranging from 5,000 to 11,000 (Hunting et al., 2001; Shuford et al. 2000; Wunder and Knopf 2003, S. Myers, pers. comm. 2002). The search efforts among years are not comparable, but represent the best available information. We believe the estimates provided are a reasonable approximation of mountain plover total abundance, given recent survey efforts directed at mountain plovers on their winter habitat, the dedicated efforts to locate them in California's Central and Imperial valleys, and their winter flocking behavior that enhances detection.

As discussed by Knopf (1996b), the continental breeding range of the mountain plover has been reduced from its historical extent, especially in the eastern portion of the range. The mountain plover was formerly common in western and central Kansas (Goss 1891), and reported as numerous between Fort Supply, Oklahoma, and Dodge City, Kansas (McCauley 1877). The species was historically numerous in Colorado (Bailey and Niedrach 1965) and Wyoming (Knight 1902). Lower numbers of mountain plovers formerly occupied western South Dakota (South Dakota Ornithologist's Union 1991) and Nebraska (Knopf 1996b), and there is one known breeding reference from North Dakota (Roosevelt 1885). There was a single report of breeding mountain plovers in northern Mexico in 1901 (Sanford et al. 1924), and breeding was confirmed in the State of Nuevo Leon in 1999 (Desmond and Ramirez 2002).

ColoradoThe Colorado Bird Atlas Partnership estimated a population of 7,200 (range from 3,652 to 12,168) mountain plovers in Colorado, with perhaps 22 percent of these in Weld County (H. Kingery, in litt. 1997; Kingery 1998). However, this population estimate should be considered a ``first approximation'' and used with caution (Kingery 1998). A more recent effort to estimate mountain plover abundance is the Rocky Mountain Bird Observatory's estimate of 4,850 individual mountain plovers in eastern Colorado (S. Gillihan, in litt. 2003).

Mountain plovers have been studied intensively in Weld County, Colorado, from the late 1960s to the present. Graul and Webster (1976) considered Weld County in northeastern Colorado the breeding stronghold for the mountain plover, a conclusion widely referenced by subsequent authors (e.g., Knopf and Rupert 1996). However, inventories completed by the Colorado Bird Atlas Partnership from 1987 through 1995 found mountain plovers more widely distributed than previously known in many other eastern Colorado counties (Kingery 1998). Based on their inventories, the Bird Atlas Partnership concluded that 75 percent of Colorado's mountain plovers occurred south of Weld County (H. Kingery, Colorado Bird Atlas Partnership, pers. comm. 1994, in litt. 1998).

Breeding mountain plovers also have been reported from southeastern Colorado by others (Chase and Loeffler 1978; Nelson 1993; R. Estelle, Colorado Bird Observatory, in litt. 1994; M. Scott, BLM, in litt. 2000; K. Giesen, Colorado Division of Wildlife (CDOW), in litt. 2001). During a 1996 inventory, Carter et al. (1996) concluded that mountain plovers occur at very low densities in 10 eastern Colorado counties, and are most numerous in Kiowa and Park Counties. Mountain plovers also have been seen in Moffat County in northwestern Colorado (Behrends and Atkinson 2000). The Colorado Natural Heritage Program conducted mountain plover surveys in Park County in central Colorado from 1994 through 2002, and currently estimate 2,300 mountain plovers at this location (Pague and Pague 1994, Sherman et al. 1996, Hanson 1997, Granau and Wunder 2001, Wunder et al. in prep.). South Park appears to currently be the most productive breeding location in Colorado, and probably throughout the entire breeding range. This is clearly the largest breeding population of mountain plovers in Colorado, and perhaps throughout the breeding range.

In Weld County, 60 to 70 percent of the mountain plover habitat occurs on the Pawnee National Grassland, a historically recognized breeding stronghold (F. Knopf, in litt. 1991). Today, nearly all mountain plovers have abandoned the Pawnee National Grassland. During the late 1960s, Graul and Webster (1976) estimated about 69,000 hectares (171,000 acres) of good habitat on the Pawnee National Grassland, with mountain plover densities of at least 10/
kilometer² (26/mile²). Based on these estimates, we calculate that at least 7,000 mountain plovers likely occupied the Pawnee in the early 1970s. Knopf (in litt. 1991) estimated about 1,280 individuals in 1991, while presently the Grassland population is about 78 individuals (F. Knopf, pers. comm. 2002).

Graul (1973) hypothesized that mountain plover productivity on the Pawnee is influenced by drought and its corresponding effects on food supply. In 1995, the Pawnee received aboveaverage spring rainfall resulting in lush vegetation growth not suitable as mountain plover nesting habitat. As a result, few birds were found there during the breeding season; conditions continued through 1996 and 1997, with few adult birds and very little reproduction observed through 2002 (Knopf 1996; F. Knopf, in litt. 2003).

Although mountain plovers nest on cultivated fields in southeast Colorado and adjacent States, 1 study (Shackford et al.1999) found that of 46 nests monitored on cultivated fields, 31 nests failed and the fate of the remaining 15 nests was unknown. Of the 31 failed nests, 22 nests (48 percent of total nests) were destroyed by farm machinery. Giesen (in litt. 2000) reported a higher nest success on agricultural fields than on native rangeland. As a result of these conflicting findings, research was initiated in five eastern Colorado counties to better describe nest success and productivity, and the implications of cultivated field nesting to mountain plover population recruitment (T. McCoy, Colorado Natural Heritage Program, in litt. 2001). In 2001 and 2002 within the study area, nests on croplands numbered 45 and 85, respectively, with the increase due to a 40 percent increase in area surveyed (V. Dreitz, in litt. 2002). Nest success on cropland and rangeland was equal in 2001, but was about 10 percent higher on range in 2002 (V. Dreitz, in litt. 2002). Predation was the major cause of nest failure on rangelands in 2001 and 2002. Predation and tillage losses were the cause of nest failure on cropland, but the combined losses on cropland were fewer than predation losses on rangeland in either year.

Based on the data presented above, we estimate over 7,000 breeding mountain plovers in Colorado.

MontanaThe largest known number of breeding mountain plovers in Montana is found on a large complex of blacktailed prairie dog colonies in the contiguous Phillips and Blaine Counties (Knowles and Knowles 2001, Dinsmore 2001). In Phillips County, nearly all mountain plovers are found on active prairie dog colonies that also are grazed by cattle (Dinsmore 2001).

Although Phillips and Blaine Counties contain a major breeding concentration for the species (Knopf and
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Miller 1994, Knowles and Knowles 2001, Dinsmore 2001), small numbers of mountain plovers also breed on BLM lands in Valley County (Little Beaver Creek), and on private land in Wheatland and Golden Valley Counties near the Little Belt and Big Snowy Mountains (Knowles and Knowles 1998). Surveys through 2003 also report mountain plovers in Big Horn, Broadwater, Carbon, Fergus, Jefferson, Hill, Madison, Musselshell, Petroleum, Rosebud, and Treasure Counties (L. Hanebury, Service, pers. comm. 2003; Knowles and Knowles 1996, 1998; J. Grensten, BLM, pers. comm. 1998).

The most recent information documents that the mountain plover population in southern Phillips County increased from about 100 individuals in 1995, to 175 individuals in 2001 (Dinsmore 2001). In 2003, over 150 nests were found on the study site (Dinsmore, pers. comm. 2003). This increase is likely due to the recovery of black tailed prairie dogs from a recent sylvatic plague epizootic. Mountain plovers at the Fort Belknap Indian Reservation increased from 0 to 20 from 1993 to 1998 following an increase in blacktailed prairie dogs and the introduction of bison grazing, and there may presently be as many as 100 individuals, although the change may be due to more rigorous inventory (Knowles and Knowles 2001; S. Dinsmore, pers. comm. 2003). Mountain plover densities on blacktailed prairie dog colonies at the Charles M. Russell National Wildlife Refuge declined by more than half from 1980 to 1996. Prairie dog numbers at Charles M. Russell National Wildlife Refuge have increased since 1996, and plover numbers have gone up slightly. Knowles and Knowles (2001) report that between 1992 and 2000 mountain plovers declined at their Central and Southwestern study areas, but increased slightly at their Northeastern study area.

Dinsmore (2001) concluded that mountain plovers in southern Phillips County are entirely dependent on an active blacktailed prairie dog population, and that the mountain plover abundance at his study site will likely parallel the population trends of blacktailed prairie dogs.

Knowles and Knowles (1996) estimated less than 2,000 mountain plovers in Phillips and Blaine Counties, and less than 800 additional individuals at the other occupied locations in the State. Based on his 6 years of research, Dinsmore (pers. comm. 2002) provided a rough estimate of 700 mountain plovers throughout all of Phillips and Blaine Counties, and noted that Knowles and Knowles (1996) estimate of 800 mountain plovers at other areas is reasonable. Therefore, we believe the best information currently available indicates the total population in Montana is approximately 1,500 mountain plovers (Knowles and Knowles 1996, Knowles and Knowles 1998, Dinsmore 2001, Dinsmore, pers. comm. 2002).

WyomingThe mountain plover is classified as common in Wyoming, with breeding known or suspected in 20 of 28 latitude/longitude blocks (latilong blocks) occurring across the entire State (Wyoming Game and Fish Department 1997). The latilong records reviewed included sightings from 1969 to 1996, with the highest number of individual records occurring in the Saratoga, Wapiti, Powell, Casper, Bill, and Laramie blocks. Because the search effort among the blocks is not equal, the number of records reported for each block is not a good indicator of mountain plover abundance within each block. Further, while latilong records may note evidence of breeding, they do not provide information regarding nesting success. Based on these latilong records, the Wyoming Game and Fish Department reports the mountain plover as common in the State, but acknowledges that information is lacking to make any estimate of total population or determine whether it is increasing, stable, or declining (Oakleaf et al. 1996).

Additional inventories have been conducted in Wyoming that confirm the presence of mountain plovers at many of the previously reported locations. For example, surveys conducted in the Powder River Basin (Campbell, Converse, Sheridan, Crook, and Weston Counties) in 2001, in preparation for the Powder River Basin Oil and Gas Project, found 15 mountain plovers (Good et al. 2002, Keinath and Ehle 2002). Most of the Powder River Basin is private land, and the surveys were conducted from public roads only. Consequently, these surveys may not be a good representation of mountain plover abundance in the Powder River Basin. From 1992 to 2002, nesting was confirmed on the Thunder Basin National Grassland (Thunder Basin) (within the Powder River Basin) in northeast Wyoming in most years (Bartosiak 1992; M. Edwards, Forest Service, in litt. 1994; T. Byer, in litt. 1997; T. Thompson, Forest Service, in litt. 2003).

Knopf (in litt. 2001b) reported that mountain plovers may be more common in Wyoming than previously believed, particularly in Carbon County. In 1999 and 2000, a total of 159 and 105 mountain plover adults were reported from Sweetwater and Carbon Counties, respectively, with many fewer individuals reported from Albany, Bighorn, Fremont, Lincoln, Natrona, Park, Sublette, and Washakie Counties (P. Deibert, in litt. 2002). Surveys near Lysite in Fremont County found 39 mountain plovers on about 530 ha (1,300 ac) of suitable habitat (L. HaydenWing, Hayden Wing Associates, in litt. 2003). Surveys for mountain plovers in south central Wyoming in 2002 found a total of 50 adults and 11 nests (HaydenWing Consultants 2002). As many as 51 mountain plovers likely occurred on Foote Creek Rim in Carbon County in 1994, but the number declined to 26 in 2002 (Young and Erickson 2003). Most plovers have vacated habitat near the wind turbines and congregated on a prairie dog colony on the northern end of the Rim (Young and Erickson 2003). Nine nests were located on Foote Creek Rim in 2000 (Young and Good 2000).

The total number of mountain plovers observed on Thunder Basin National Grasslands declined from 53 to 37 from 1993 to 2002, while the area surveyed during this time quadrupled (T. Thompson, in litt 2003). Blacktailed prairie dog colonies in the area were affected by a significant plague event in 2001 and 2002. Mountain plovers on Thunder Basin nest almost entirely on blacktailed prairie dog colonies (Keinath and Ehlen 2002).

From 1979 to 2002, nesting was confirmed on and near the Antelope Coal Mine in the southern Powder River Basin, and breeding densities were reported to range from 0.9 to 2.4 birds/km² (2.3 to 6.2/mi²) (Oelklaus 1989, Thunderbird Wildlife Consulting, Inc. 2003). From 1982 to 1991, a total of 26 broods were reported on mine permit areas, while only 6 broods have been reported on the same permit areas from 1992 to 2002 (Thunderbird Wildlife Consulting, Inc. 2003). Parrish (1988) inventoried mountain plovers over an extensive area of the southern Powder River Basin, and reported an overall density of about 0.1 mountain plover/km² (0.3/
mi²). Mountain plovers throughout the southern Powder River Basin are generally thought to be widely scattered at low densities, with a few areas of local concentrations (Oelklaus 1989). Inventories from the Laramie Plains and Cheyenne Plains in the late 1950s report densities ranging from 0.3 to 23.8 mountain plovers/km² (0.9 to 61.9/mi²) (Laun 1957, Finzel 1964). Therefore, densities reported from the southern Powder River Basin in the 1980s are less than those reported from the Laramie and Cheyenne Plains in the 1950s, but it is unknown whether the difference is due to a decline in [[Page 53086]]
mountain plover abundance, inherent differences in habitat quality, or both.

Knopf (in litt. 1991, 2001b) found mountain plovers on the Laramie Plains, in the vicinity of Shirley Basin, on the Chapman Bench (Park County) north of Cody, and on Mexican Flats (Carbon County) northwest of Baggs. Specific surveys of Chapman Bench between 1988 and 1999 found between 7 to 14 adult mountain plovers and some juveniles (P. Deibert, pers. comm. 1999a).

Mountain plovers also breed in shrubsteppe habitat in southwest Wyoming (Oakleaf et al. 1982). The BLM estimates 10 to 15 breeding pairs in the Jack Morrow Hills north of Rock Springs in Sweetwater County (L. Keith, BLM, pers. comm. 1999). Mountain plovers reported from Morton Pass in Albany County have declined from about 30 in 1997 to about 5 in 2000 (Young and Erickson 2003).

Based on the best information available from Wyoming, mountain plovers may number from 2,000 to 5,000 individuals (P. Deibert, pers. comm. 2003; F. Knopf, in litt. 2003).

NebraskaA nesting mountain plover was found in Kimball County in western Nebraska in 1990 (F. Knopf, in litt. 1990), and two mountain plover nests were found in a fallow field in the same vicinity in 1997 (W. Jobman, Service, in litt. 1997). Seventeen mountain plovers were counted on 10 cultivated fields in western Nebraska in 1992 and 1995 (Shackford and Leslie 1995), and 1 nest was found in summer fallow in Kimball County in 1999 (W. Jobman, in litt. 1999).

No mountain plovers were found in 2001, following inventories of 92 sites, including blacktailed prairie dogs colonies, in 8 western Nebraska counties (K. Nelson, Nebraska Game and Parks Commission, in litt. 2003). The lack of mountain plovers may have been due to the survey occurring late in the breeding season. In 2002, a survey occurred in Kimball County exclusively, which is dominated by dry land wheat farming with very little shortgrass prairie. A total of 118 mountain plovers were found at the 66 locations surveyed, and all but 1 individual were in wheat fields. A total of 27 juvenile mountain plovers also were seen, with most of these in tilled, fallow ground. We have no information to assess trends in Nebraska, but the Nebraska Game and Parks Commission is concerned about the bird's viability in the State (K. Nelson, in litt. 2003).

New MexicoSager (1996) noted that the mountain plover was reported as ``fairly common'' in New Mexico in 1928, and recognized that the 152 mountain plovers he surveyed in 1995 would not likely be construed as ``fairly common'' today. However, he cautioned that mountain plovers may be more numerous than he reports because of their difficulty in detection and clumped distribution. Sager (1996) also reported that New Mexico is likely on the fringe of acceptable mountain plover habitat. We are not aware of a total population estimate or population trend for New Mexico.

OklahomaHistoric records of mountain plovers east of Cimarron County do not mention breeding behavior, so it is unclear whether the mountain plovers reported were nesting or migrating to other locations. Hence, both the historic and current distribution may be confined to Cimarron County in the panhandle of Oklahoma. In Cimarron County during the nesting seasons of 19861990, Shackford (1991) observed 15 mountain plovers in native grassland and 10 in cultivated fields. Ten of the 15 birds observed in native grassland were on prairie dog colonies. The few plovers found, combined with the discovery of one mountain plover nest on a maize field, stimulated searches of cultivated fields in Oklahoma in 1992, 1993, and 1994. Using approximately the same search method and effort each year, 408, 428, and 108 individual mountain plovers were found on cultivated fields in each of these years, respectively, and up to 13 nests were found on the cultivated fields from 1986 through 1995 (Shackford et al. 1999, Shackford and Leslie 1995). The plovers reported include both plovers seen during the breeding season as well as mountain plovers in premigratory flocks. The decline in 1994 is attributed to a decline in mountain plovers seen during the nonbreeding season, not necessarily a decline in breeding birds. No other surveys have been completed in Oklahoma, and estimates of the total Statewide population have not been made (S. Harmon, Service, pers. comm. 2002).

KansasCounts of breeding mountain plovers on cultivated lands in western Kansas from 1992 through 1995 ranged from 52 (6 counties searched) to 114 (4 counties searched) (Shackford and Leslie 1995). Surveys of cultivated fields and rangelands within the boundary of the Cimarron National Grassland (Cimarron) in Kansas also have been conducted. Counts on the Cimarron in 1994, 1996, and 1997 ranged from 1 to 13, with most of the sightings on plowed fields (J. Chynoweth, Forest Service, in litt. 1997).

Other Breeding AreasIn Utah, the only site known to have breeding mountain plovers is in Duchesne County, south of Myton, in the Uinta Basin. Counts of breeding mountain plovers in this area from 1992 through 2001 ranged from 6 to 29. From 1992 to 2001, broods were found in all years except 1992, 1999, and 2001; six adults and no broods were found in 2001; and no mountain plovers were seen in 2002 (T. Dabbs, BLM, in litt. 1997; F. Knopf, in litt. 1999; B. Stroh, Forest Service, pers. comm. 2002).

Three pairs of nesting mountain plovers were reported near Fort Davis, Texas, in 1992 (K. Brian, Davis Mountain State Park, pers. comm. 1992). More recent breeding in Texas has not been reported due to lack of access to private land (P. Horner, Texas Parks and Wildlife Department, in litt. 1997).

From 1914 to the present, mountain plovers in Arizona have been reported during the breeding season from Apache, LaPaz, Maricopa, and Navajo Counties. A pair was found on Navajo Nation land near Winslow in June 1995, and an adult incubating three eggs was found near Springerville, Apache County, Arizona, in May 1996 (T. Cordery, Service, pers. comm. 1998; D. Shroufe, Arizona Game and Fish Department, in litt. 1999). In May 2002 breeding behavior was observed in three birds west of Springerville, in Apache County (Ted Cordery, BLM, pers. comm. 2003).

The most recent nesting record in Canada was one nest in southeastern Alberta in 1989 (S. Jewell, Service, in litt. 2000). No mountain plovers were found during searches conducted in Alberta and Saskatchewan in 2001 (C. Wershler, Sweetgrass Consultants, pers. comm. 2002).

Mountain plover breeding behavior was observed in 1998 in Nuevo Leon, Mexico, and one nest was found on a Mexican prairie dog colony in 1999 (Knopf and Rupert 1999a, Desmond and Ramirez 2002).

We believe that Montana, Wyoming, and Colorado represent the historic and current core mountain plover breeding range, although additional peripheral locations in Oklahoma and New Mexico may play an important role in the species' conservation.

Historically, mountain plovers have been observed during the winter in California, Arizona, Texas, Nevada, and on the California coastal islands of San Clemente Island, Santa Rosa Island, and the Farallon Islands (Strecker 1912; Swarth 1914; Alcorn 1946; Jurek 1973; Garrett and Dunn 1981; Jorgensen and Ferguson 1984; B. Deuel, American Birds Editor, in litt. 1992; D. Shroufe, in litt. 1999). In Mexico, wintering mountain plovers have been sighted in
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Baja California, as well as northcentral and northeastern Mexico, in Sonora, Chihuahua, Coahuila, Durango, Nuevo Leon, and San Luis Potosi (Russell and Lamm 1978; A. Garza de Leon, The Bird Galley, in litt. 1990; L. Stenzel, Point Reyes Bird Observatory, in litt. 1992; Gomez de Silva et al.1996; Knopf and Rupert 1999a; Dieni et al. 2003, J. Taylor, pers. comm. 2003).

All information we have reviewed indicates that California is the primary wintering ground for mountain plovers, supporting up to 95 percent of the United States' population of mountain plovers (Morey, in litt. 2003). However, recent isotope studies indicate that there may be a disproportionate number of males in the wintering flocks. Seventy five percent of the feathers sampled from the Imperial Valley in the winter of 2002 were from males, and sixtytwo percent were from males in the winter of 2003. This could indicate a slightly higher female mortality, or perhaps differential migration patterns between male and female plovers (e.g. females wintering farther south into Mexico). More stable isotope work in the next two years may help answer this question (Knopf, pers. comm. 2003).

Mountain plovers are most frequently reported and found in the greatest numbers in two general locations in California(1) The western Central Valley from Solano and Yolo Counties to Kern County (primarily the western San Joaquin Valley), and (2) the Imperial Valley in Imperial County. Throughout these areas, sightings occur on agricultural fields and noncultivated sites. Research conducted in the San Joaquin Valley concluded that the noncultivated sites are the preferred habitat there, while cultivated sites are the exclusive habitat in the Imperial Valley (Knopf and Rupert 1995, Wunder and Knopf 2003).

From 1961 to 1968 anywhere from 25 to 10,000 mountain plovers were counted in winter on Kern National Wildlife Refuge in the San Joaquin Valley (J. Engler, Service, in litt. 1992). In January 1994, researchers counted 3,346 mountain plovers during a simultaneous 1day survey of 25 sites throughout California (B. Barnes, National Audubon Society, in litt. 1994). A similar coordinated survey at 31 sites in the Central and Imperial valleys in January 1998 estimated 2,663 mountain plovers (Hunting et al. 2001). In December 1999, two skilled observers were unable to find any mountain plovers in the entire San Joaquin Valley after 2 days searching traditionally occupied sites (Dinsmore, in litt. 2000b), which may have been due to degraded habitat conditions following heavy rains (F. Knopf, pers. comm. 2000). On February 2, 2002, 536 mountain plovers were counted in the entire San Joaquin Valley, which may indicate some recovery of habitat conditions since 1999 (S. Fitton, in litt. 2002). Within the San Joaquin Valley, premigratory flocks of up to 1,100 birds have been seen in Tulare County (Knopf and Rupert 1995). The Carrizo Plain (separated from the San Joaquin Valley by the Tremblor Range) also is recognized as a predictable wintering site, with wintering birds reliably reported from the west side from 1971 to 1998 (S. Fitton, in litt. 1992,
www.birdsource.org 2000). Solano and Yolo Counties in the Central Valley near Sacramento also provide wintering habitat for mountain plovers, with about 200 being seen in these counties in recent years (K. Hunting, California Department of Fish and Game, in litt. 1998; C. Conard, Sacramento Audubon, in litt. 2003).

Wunder and Knopf (2003) suggested that many mountain plovers have apparently shifted from the Central Valley as a result of habitat loss to southern California and the Imperial Valley. Recent search efforts and records for the Central Valley classify the mountain plover as rare and local, exceedingly rare, or accidental, within individual counties in the San Joaquin Valley (Edson and Hunting 1999; K. Hunting, California Fish and Game, pers. comm. 2003).

In the Imperial Valley, coordinated surveys occurred in February, November, and December 1999. The maximum effort of 26 observers in 15 parties over 2 days located 3,758 mountain plovers in December (Shuford et al. 2000). From January 919, 2001, 4,037 mountain plovers were counted by 2 observers in the Imperial Valley (Wunder and Knopf 2003), and 3,421 were counted there from January 29 to February 6, 2002, by 4 observers (S. Myers, AMEC Earth and Environmental, pers. comm., 2002). In the 2002 Christmas Bird Count (CBC) for that area only 12 were counted; surveys were abandoned in January 2003 when the birds could not be found following heavy rains (Knopf, pers. comm, 2003).

The only consistently collected information available to judge a population trend are the CBC data. The CBC data from 19551999 from all count circles in California reporting mountain plovers indicated a decline in mountain plovers of about 1 percent annually (J. Sauer, U.S. Geological SurveyBiological Resource Division (USGSBRD), in litt. 2000; Wunder and Knopf 2003). This equates to a 35 percent decline in the population from 1955 to 1999 (J. Sauer, pers. comm. 2003). The CBC numbers fluctuate greatly from year to year based on observer variability, survey intensity, and the spatial and temporal distribution of mountain plovers (AMEC Earth and Environmental 2003).

Arizona, Texas, Nevada, and MexicoWintering mountain plovers also are reported from other areas, but in much lower numbers than are reported from California. From 1914 to the present, up to 340 mountain plovers have been reported during the winter from Cochise, Maricopa, Pima, Pinal, and Yuma Counties in Arizona (D. Shroufe, in litt. 1999). In Texas, up to146 mountain plovers were reported from Guadalupe, San Patricio, and Williamson Counties (J. Maresh, no affiliation, pers. comm. 1999; G. Lasley, American Birds, pers. comm. 1992). Mountain plovers also have been sighted throughout the year in Aransas, Concho, Kleberg, Nueces, Schleicher, Tom Green, and Val Verde Counties in Texas (P. Horner, in litt. 1997), and at Laguna Atascosa National Wildlife Refuge on the Texas coast (L. Laack, Service, in litt. 1992). About 400 wintering mountain plovers were reported in west Texas in 2003 (T. Fennell, unaffiliated, in litt. 2003). In Nevada, several mountain plovers were collected in the Lahontan Valley in 1940, and a few have been reported in the Fallon CBC circle in the 1990s (Alcorn 1946, www.birdsource.org 2000). In January 1992, researchers counted 148 mountain plovers at the north end of Laguna Figueroa, Baja California, Mexico (L. Stenzel, in litt. 1992). In 1994, mountain plovers were seen on a Mexican prairie dog colony in San Luis Potosi, Mexico (Gomez de Silva et al. 1996). In January 2000, 110 mountain plovers were found on blacktailed prairie dog colonies in Chihuahua, Mexico (S. Gillihan, in litt. 2003). Winter surveys for mountain plovers in Mexico completed during the past several years have failed to find any populations that approach the numbers found in California (R. Estelle, pers. comm. 1998).

In summary, with the heightened awareness to wintering mountain plovers during the past decade (including blackfooted ferret recovery planning on prairie dog colonies in Mexico), and the mountain plover's winter flocking behavior, we believe it is unlikely that significant numbers of mountain plovers are not being detected. The widespread distribution of the species makes it difficult to obtain comprehensive population counts.
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Previous Federal Action

On December 30, 1982, we designated the mountain plover as a category 2 candidate species, meaning that more information was necessary to determine whether the species status was declining, stable, or improving (47 FR 58458). In 1990, we prepared a status report on the mountain plover indicating that Federal listing may be warranted (Leachman and Osmundson 1990). We elevated the mountain plover to a category 1 candidate species in the November 15, 1994, Animal Candidate Notice of Review (59 FR 58982). At that time, category 1 candidate species were defined as those species for which we had sufficient information on biological vulnerability and threats to support issuance of a proposed rule to list. In 1996, we redefined candidate species and eliminated category 2 and 3 candidate designations (61 FR 64481). Candidate species were defined using the old category 1 definition. The mountain plover retained its candidate species designation as reported in the September 19, 1997, Review of Plant and Animal Taxa (62 FR 49398). On July 7, 1997, we received a petition to list the mountain plover as threatened from the Biodiversity Legal Foundation. The Service responded by notifying the petitioner that petitions for candidate species are considered second petitions, because candidate species are species for which we have already decided that listing may be warranted. Therefore, no 90day finding was required for the Biodiversity Legal Foundation's petition. We published a proposed rule to list the mountain plover as threatened on February 16, 1999 (64 FR 7587), and requested that comments be provided by April 19, 1999. We announced public hearings for the proposal on April 19, 1999, and concurrently extended the comment period to June 21, 1999 (64 FR 19108).

Higher priority listing actions precluded listing work on the mountain plover during Fiscal Years 2000 and 2001. On October 16, 2001, Earthjustice (representing the Biodiversity Legal Foundation, Biodiversity Associates, and Center for Native Ecosystems) submitted a 60day Notice of Intent to sue to the Secretary of the Department of the Interior and the Service Regional Director for failure to meet listing deadlines for the mountain plover, as required by section 4(b)(6)(A) of the Act. The Service responded to Earthjustice on December 21, 2001, with a commitment to submit an amended listing proposal for the mountain plover by September 30, 2002. On October 7, 2002, we agreed to prepare a document to reopen the public comment period for this listing decision by November 30, 2002; hence, the December 5, 2002, notice to reopen the comment period (67 FR 72396). On February 21, 2003, we extended the comment period to March 21, 2003 (68 FR 8487).

Summary of Comments Received on the Proposed Rules

In both the February 16, 1999, proposed rule (64 FR 7587) and the December 5, 2002, proposed rule (67 FR 72396), all interested parties were requested to submit factual reports or information that might contribute to the development of a final determination. Federal and State agencies, county governments, scientific organizations, and other interested parties were contacted and requested to comment. Several newspaper articles appeared in Montana, Wyoming, and Colorado following our distribution of background materials to print media. We also solicited and received the expert opinions of three independent specialists regarding pertinent scientific or commercial data and issues relating to the biological and ecological information for the mountain plover. We received a total of 194 written comments on the 1999 proposed rule.

We distributed a press release to announce the 2002 proposed rule. We again solicited peer review of independent specialists regarding the listing proposal and special rule. We received a total of 65 written, email, or telephone comments on the 2002 proposed rule.

In response to the 1999 proposed rule, public hearings were requested in Nebraska by the Forest Service; in Montana by the Phillips County Prairie Ecosystem Action Council, the Phillips County Board of County Commissioners, and Erin Crowder; and in Wyoming by the Park County Board of County Commissioners, Wheatland Irrigation District, Wyoming Farm Bureau Federation, Laramie County Conservation District, Platte County Resource District, Antelope Grange, Mountain Valley Livestock, Inc., Ultra Resources, and John and Phyllis Thalken.

Public hearings were held at the following locations and dates: [sbull] Billings, Montana, May 26, 1999.
[sbull] Malta, Montana, May 25, 1999.
[sbull] Greeley, Colorado, May 25, 1999.
[sbull] Lamar, Colorado, May 26, 1999.

[sbull] Casper, Wyoming, June 2, 1999.

We received written and verbal comments from State and Federal elected officials, State and Federal agencies, nongovernmental organizations, and private citizens. We received a total of 52 comments at the 5 public hearings. Of the total 246 written and verbal comments received on the 1999 proposed rule, 136 opposed, 41 supported, 53 expressed concern about the proposal, and 16 sought a list of the references or requested public hearings.

Following release of the December 5, 2002, proposed rule, we received requests for public meetings from Congressman Bob Filner representing the 50th District of California, the Oklahoma Farm Bureau, the Kansas Farm Bureau, and the Nebraska Farm Bureau. Following discussions with each of these individuals, we held public meetings at the following locations:
[sbull] El Centro, California, January 23, 2003.

[sbull] Elkhart, Kansas, February 5, 2003.

The Service distributed news releases announcing the meetings in El Centro, California, and Elkhart, Kansas, on January 16, 2003, and January 29, 2003, respectively. Notification of the Elkhart meeting also appeared on the local access television station within the Elkhart, Kansas, viewing area.

We received a total of 11 verbal comments from the 2 public meetings held in 2003. Of the total of 75 verbal and written comments received on the December 5, 2002, proposed rule, 25 comments opposed the listing proposal, 15 supported the proposal, 24 expressed concern, and 11 requested an extension of time or public hearing.

All written and verbal comments presented at the public hearings and received during the public comment period, including peer review comments, were considered in preparing this final determination. Most of the comments opposing the action criticized the quality of the science used to support the proposal, stated that we did not thoroughly address each listing factor, noted the potential for the Federal listing to restrict activities on both public and private lands, and suggested that listing should be delayed to allow other alternatives to work to conserve the species (e.g., conservation agreements). Some comments also challenged the value of listing the species, and argued that listing the mountain plover will conflict with other species' conservation efforts and the implementation of other Federal programs. Other respondents supported listing because of the decline in the distribution and numbers of mountain plovers and the potential future natural or mancaused actions to result in further decline of the species, and also asked that critical habitat be designated. Each of the five peer reviewers (three in
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1999, two in 2002) indicated that the proposed rule contained sufficient scientific information to support proposed listing. We have consolidated similar comments, organized them by central themes, and provide our responses below.

Listing Decision Statute Issues

Comment 1: The Service has violated statutory intent by not complying with `the best information available' standard, has inappropriately `piggybacked' a new proposal on the `stale' 1999 proposal, and has shown deferential treatment to environmental organizations, evidenced by the settlement agreement with Earthjustice.

Response 1: This final determination presents a significant amount of new information that has become available since the 1999 proposed rule, including new information that caused us to discount Breeding Bird Survey (BBS) trends as statistically insignificant, and to reconsider what we earlier proposed as threats on agricultural lands on the breeding grounds. The settlement agreement does not reflect preferential treatment, but rather an appropriate means to resolve litigation where the final determination was overdue.

Comment 2: Emails, personal communications, and letters do not meet the `best information available' standard as described in Service policy (59 FR 34271).

Response 2: Our policy, as cited above, requires that we evaluate all scientific and other information available, which may include 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, credible, and represents the best information available regarding the species under review. We must document our evaluation of any information we use in reaching our decision, whether it supports or refutes that decision.

Biased Decision Issues

Comment 3: Several commenters stated that our analysis of the mountain plover population trend data, grassland conversion statistics, oil and gas development projections, prairie dog population data, and other issues, are specific examples of the Service's use of `selective science.' The commenter believe the Service has `selected science' to defend a listing position in the proposed rules, while ignoring information that defends the withdrawal of the listing proposal.

Response 3: During the two public comment periods in 2002 and 2003, we received numerous comments from affected States and other interested parties. We have based our decision on our review of all the pertinent information we received. This determination includes new and additional information, including research results, that was not available for the proposed rule.

Comment 4: The multipleclutch breeding system of the mountain plover influences the annual fluctuation in the population, and prepares the mountain plover for a changing environment.

Response 4: Multipleclutching is believed to be a strategy that allows the mountain plover to respond to abundant prey (Graul 1973) which can, therefore, result in annual fluctuations in mountain plover numbers at individual breeding locations. We agree that annual fluctuations in mountain plovers may be in response to prey, but the affect of multiclutching on population trends is unknown.

Comment 5: The Service understated the effects of predation on mountain plovers, did not consider the invasion by red fox (Vulpes vulpes), and did not describe what is going to be done to reduce predation effects on mountain plovers. Predation has a much greater effect on the mountain plover population than losses on croplands.

Response 5: We have revised the section on predation to include red fox as a potential predator, and assess the implications of predation to mountain plover conservation. However, red fox are not typically associated with habitats occupied by mountain plovers.

Comment 6: The Service has not identified or quantified actual threats and, therefore, has not shown that mountain plovers have declined or are at risk.

Response 6: The commenter is correct that we have not quantified the threats to the mountain plover or the number of individuals lost as a result of each threat. We have based our determination to withdraw on the wide distribution of the mountain plover and the relative security of the species from present or foreseeable threats across its current range.

Habitat Characteristics Issues

Comment 7: Mountain plovers are not at risk when nesting on croplands. Current agricultural practices are beneficial to the mountain plover.

Response 7: In the 1999 proposed rule, we stated that agricultural practices on cultivated lands may contribute to the decline of mountain plovers. Research has confirmed that some nests are lost to some cultivation practices (Dreitz and Knopf, in litt. 2003). As reported in this final determination, preliminary research findings from Colorado suggest that nesting success on cultivated lands does not differ significantly from nesting success on grassland nesting sites (Dreitz and Knopf, in litt. 2003). We agree that nesting success on some croplands is similar to that found on grasslands, but the relative influence of each landscape on mountain plover population recruitment has not been determined.

Comment 8: Cultivated lands provide habitat where none existed before.

Response 8: Cultivated lands have replaced grasslands within the historic breeding and wintering range of the mountain plover. Hatching success on cultivated lands and grasslands appears to be similar in the southern portion of the breeding range.

Comment 9: Mountain plovers are an adaptable species, and have effectively shifted from grasslands to cultivated lands in many breeding and wintering areas. Cultivated lands, not grasslands, are now the most important habitat for mountain plovers at both breeding and wintering locales.

Response 9: See response to Comments 7, 8, and 21.

Comment 10: The role of insect availability has not been thoroughly evaluated, particularly given that livestock dung is less abundant than bison dung, and the prevalence of dung influences insect abundance. Also, systemic insecticides are used on cattle, which reduces insect availability.

Response 10: We agree that the role of insect availability has not been thoroughly evaluated. However, no information has been provided to show that insect abundance or diversity have been significantly modified by the replacement of bison with domesticated livestock, or that the use of systemic pesticides influences insect abundance or composition.

Comment 11: Mountain plover habitat is provided by several factors such as low moisture, drought, herbivory, fire, and grazing. In Montana, unique soil types are the key element in defining suitable mountain plover habitat. Prairie dog colonies are not the only suitable habitat.

Response 11: We agree that numerous factors can provide suitable mountain plover habitat. We agree that soils are important to providing the vegetation and bare ground required by nesting mountain plovers. For example, Beauvais and Smith (2003) stated that poor soil, low precipitation, and wind scour help provide the proportion of bare ground needed by nesting mountain plovers in the Jack Morrow [[Page 53090]]
Hills area of southwest Wyoming. However, the literature also is replete with examples documenting the association of mountain plovers with prairie dogs (e.g., Dinsmore 2001, Knowles 1999, Kotliar et al. 1999).

Comment 12: Habitat fragmentation and isolation increase the mountain plovers vulnerability to random natural and humancaused events.

Response 12: No scientific information specifically discusses the influence of fragmentation or isolation on the persistence of mountain plovers at currently occupied breeding and wintering sites.

Comment 13: The anticipated growth at South Park will impact mountain plovers and their habitat.

Response 13: Complete development of South Park into private homes would probably adversely impact mountain plover. However, the anticipated growth at South Park will be lowdensity residential development, and full buildout is not anticipated in the foreseeable future since the current human population in Park County is small (16,000 people). It also is likely that conservation efforts ongoing in South Park will preserve important mountain plover habitat. Consequently, we believe potential threats to mountain plovers that might result with development will be offset by conservation measures implemented at the State and county levels.

Mountain Plover Distribution Issues

Comment 14: All suitable habitat on private and public lands throughout the breeding range of the mountain plover has not been thoroughly inventoried. Additional searching in the breeding range has consistently found more mountain plovers.

Response 14: We have revised the population estimates for individual States based on new information from commenters and literature. We agree that surveys on all private lands in the breeding range could reveal additional birds. For that reason, in addition to the birds' flocking tendencies in winter, and 44 years of CBC data, we base our total population estimate on counts from wintering habitat in California, not on a summation of counts from breeding locales. Mountain plovers occurring at undetected breeding locations would be expected on the winter habitat from October through midMarch. This estimate assumes that most of the birds winter in California.

Comment 15: All wintering areas in the United States or Mexico have not been located. Further searching will yield more wintering sites and more mountain plovers.

Response 15: All historic and current information we have reviewed support California as the key wintering location for mountain plovers, with many fewer numbers occurring elsewhere. Searches for mountain plovers on wintering grounds in Mexico have been ongoing for the past several years. We agree that additional searching is likely to find other sites used by mountain plovers, but we believe that finding large numbers of wintering mountain plovers will be highly unlikely, given the level of effort dedicated in the United States and Mexico over the past decade to locating mountain plovers. We have revised this section of our determination to cite new information provided during the comment period.

Mountain Plover Total Population and Trends Issues

Comment 16: The mountain plover is declining throughout its range, and its current abundance is low compared to other bird species.

Response 16: The CBC data from wintering grounds in California identify a slow decline in mountain plover abundance the last 44 years. However, the numbers vary widely from year to year, and their accuracy cannot be determined with any certainty.

Comment 17: The population estimate in the 1999 and 2002 proposed rules is just ``a guess'' and is not reliable.

Response 17: The majority of wildlife population numbers are estimates, because it is rarely possible to count all the individuals of a species to develop a precise population number. We have relied on practices accepted in conservation science, using the best information available to us, to provide the public with a total population estimate. The total population estimate of 8,000 to 10,000 individuals was made by Dr. Fritz Knopf, a Senior Scientist with USGSBRD in Fort Collins, Colorado. Dr. Knopf has been studying mountain plovers since 1986, and has published widely on the mountain plover throughout its range. We believe he is well qualified to make a population estimate. Dr. Stephen Dinsmore, who recently completed his doctoral research on mountain plovers in Montana, agrees with the population estimate. The only other estimates available are those we have developed for individual States in the breeding range based on other sources of information.

The estimate is based on a 1day coordinated survey on the winter habitat in 1994, which was conducted by 95 observers covering 25 sites in 9 counties. In addition, both planned and incidental searches to locate and report mountain plovers in California have been ongoing for decades.

Many respondents challenged the reliability of the population estimate because of its reliance on a 1day winter survey, and its failure to include the numerous mountain plovers that they believe occur on private lands throughout the nesting range. Counting animals on their winter habitat is an accepted technique for estimating the abundance of many species, with migratory waterfowl and big game being two examples. The survey coordinated by the National Audubon Society in California was a legitimate approach to monitor a wintering species, and represented a new effort to count mountain plovers.

The commenters are correct in stating that the population estimate alone cannot be used as a basis for listing. We have provided the abundance and distribution information to give the public a better sense of the status of the mountain plover.

Comment 18: How can the Pawnee National Grassland and Charles M. Russell National Wildlife Refuge be important when so few mountain plovers occupy these sites?

Response 18: We emphasized the significance of the Pawnee National Grassland because of its historic importance to the mountain plover, its Federal ownership and management, and its potential contribution to mountain plover conservation. We identified the Charles M. Russell National Wildlife Refuge because of its location in Phillips County, Montana, an area with suitable and potentially suitable habitat and currently one of the largest breeding mountain plover populations. We believe each of these properties, with proper management, can make significant contributions to mountain plover conservation on public lands.

Comment 19: The Service did not acknowledge that Dr. Walter Graul's 1976 population estimate for the Pawnee National Grassland is now considered inaccurate.

Response 19: We discussed this issue with Dr. Graul in preparing this final determination. The commenter correctly notes that subsequent to Dr. Graul's 1976 estimate of 20,000 mountain plovers on the Pawnee National Grassland, he stated that it may have been off by an order of magnitude. Dr. Graul provided the 1976 estimate to satisfy a request of the American Ornithological Union to establish a relative magnitude of abundance for the mountain plover. However, Dr. Graul believes that mountain plovers were much more numerous during his
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research than have been noted in recent years by himself or Dr. Fritz Knopf. Consequently, while our use of historic numbers to show a declining trend at the Pawnee National Grassland can be challenged, Dr. Graul and Dr. Knopf both agree that a significant decline has been evident since the late 1960s. We have revised the appropriate section of the final determination.

Comment 20: The present and future change in winter habitat in California is a significant rangewide threat to mountain plovers.

Response 20: As described in this final decision, we do not believe the anticipated conversions of cultivated and noncultivated habitats in California will have an immediate significant impact on wintering mountain plovers throughout California. We discussed this issue with Dr. Fritz Knopf for preparation of this final determination (F. Knopf, pers. comm. 2003). Dr. Knopf agreed that winter habitat does not appear to be limited, but acknowledged that habitat quality may not be similar among all cultivated and noncultivated lands. Mountain plovers are opportunistic foragers while they occupy winter habitat, and have the ability to seek suitable habitats available over a wide area. Knopf and Rupert (1995) determined that mountain plovers prefer noncultivated sites to cultivated lands, and others have observed that mountain plovers appear to select unique characteristics (E. MarquisBrong, BLM, in litt. 1999). However, given that cultivated habitat is pervasive throughout the Imperial and Central Valleys, we do not believe the current rate of conversion represents an imminent threat to mountain plovers.

Comment 21: Mountain plover numbers are very dynamic, and their current abundance merely reflects a normal fluctuation.

Response 21: We agree that mountain plover abundance at local breeding areas can fluctuate annually based on local environmental conditions.

Comment 22: Population fluctuations due to climatic events should be considered temporary and not a justification for listing.

Response 22: The Service must consider all factors, natural or humancaused, that may contribute to a species' survival and recovery. We agree that climatic events may affect localized populations, either positively or negatively, on a temporary basis. Presently, it is believed that climatic events on the Pawnee National Grassland have negatively influenced mountain plover abundance there.

Comment 23: The BBS data are not reliable. The 2002 proposed rule stated that new BBS information was available, but new BBS information could not be found.

Response 23: The 1999 proposed rule cited literature published by Dr. Fritz Knopf, which used published BBS trend analyses reporting the mountain plover declining throughout its range, and declining more rapidly than other grassland endemic birds. His conclusions were based on the BBS data for the periods from 1966 to 1993. The 1999 proposed rule also cited an analysis by Dr. John Sauer with the USGSBRD, showing that for the period 1966 to1996, the BBS trend analysis yielded a statistically significant estimated annual rate of decline of 2.7 percent. Because of the numerous comments we received on the 1999 proposed rule regarding the BBS data, we requested a review of the data by the USGSBRD, which is the Federal agency responsible for administering the BBS program.

According to Sauer (in litt. 1999), the surveywide trend analysis lacked statistical confidence due to the wide variability in mountain plovers reported from individual routes in each of the years from 1967 to 1998. We concluded that, although the BBS is the only longterm trend information available in the breeding range, it is not a statistically reliable indicator of mountain plover population trends.

Comment 24: A commenter criticized the 30yearold National Wildlife Refuge records because of a lack of information, the variability in observer experience, and inconsistency in survey routes followed.

Response 24: In 1992, we received a report from the Kern National Wildlife Refuge that consolidated mountain plover observations and discussed their historic and current status on the Kern and Pixley National Wildlife Refuges in California (J. Engler, Service, in litt. 1992). The report included observation records from 1961 to 1991, and lacked data for many years during that period. The records of mountain plover sightings from the refuges were collected during inventories for waterfowl, which included observations of migrating shorebirds and other species. It is common for annual waterfowl surveys to be conducted by different people, given staff turnover and personnel availability. However, refuge biologists are thoroughly trained in bird identification, and, more importantly, because the mountain plover was known as a regular resident of these refuges, we are confident that the biologists completing the survey were able to correctly identify mountain plovers when encountered. We agree that the refuge data provide an approximate estimate rather than a precise number of mountain plovers wintering on the refuge.

Comment 25: The CBC data are unreliable because count circles are not always the same over time, errors have been published by American Birds, the number of individuals reported could be wrong, and the wrong species can be reported.

Response 25: We agree that CBC numbers fluctuate greatly from year to year based on observer variability, survey, intensity, and the spatial and temporal distribution of mountain plovers. We contacted Mr. Geoff LeBaron of the National Audubon Society, who is in charge of the CBC surveys and is responsible for analyzing the data; he is familiar with the suggested limitations (G. LeBaron, National Audubon Society, pers. comm. 1999). Mr. LeBaron agreed that some count circle centers may change over time, due to encroachment of development within the count circle and, therefore, may not be completely ``static'' over the entire period of record. However, he did not believe this seriously compromises the quality of the data for the geographic area over the long term. He also agreed that the other limitations cited by the commenter can occur when field data are being evaluated for species that occupy similar habitats, or are similar taxonomically. However, because the mountain plover is unique in these respects and, therefore, unlikely to be confused with any other species by experienced observers, he does not believe any of these limitations apply to the mountain plover. The Anadarko Petroleum Corporation retained Dr. Mark Boyce to analyze the CBC data (M. Boyce, University of Alberta, in litt. 2003). Dr. Boyce's analysis did not refute the conclusions of Dr. John Sauer with USGSBRD (in litt. 2000). We have revised the section in this final determination to report additional information regarding the CBC.

Comment 26: Population trends of the mountain plover at the Pawnee National Grassland are indicative of the total population trend.

Response 26: There is no scientific evidence to support the claim that the precipitous decline documented at the Pawnee National Grassland has influenced the total mountain plover population.

Comment 27: The mountain plover's short lifespan makes the species vulnerable to decline.

Response 27: There is no scientific evidence to support the commenter's claim that the mountain plover's risk of
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extinction is exacerbated by a short lifespan.

Grassland Conversion Issues

Comment 28: Grassland conversion has destroyed mountain plover habitat and resulted in a decline in mountain plovers.

Response 28: We are unable to precisely quantify the amount of mountain plover habitat that has been lost due to agricultural conversions and, therefore, are unable to precisely quantify the impact to mountain plovers. We do not believe the present or future conversion of grasslands is an imminent threat to all mountain plover breeding locations, throughout the species' range.

Comment 29: The Service overstated the loss of grasslands as an impact on breeding mountain plovers, because the rangeland loss reported in the 2002 proposed rule is minuscule relative to total rangeland available. This means that the impact to mountain plover habitat is even smaller and, therefore, of no consequence.

Response 29: We agree that most grassland conversion occurred prior to 1982, and that the proportion of rangeland lost to total rangeland from 1992 to 1997 is small. We have revised the section of the final determination addressing grassland conversion.

Comment 30: The Service inappropriately analyzed the National Resource Inventory database in its description of rangeland conversion loss, and the implications to mountain

FOR FURTHER INFORMATION CONTACT Allan Pfister, Assistant Field Supervisor, Grand Junction, Colorado (see ADDRESSES), telephone 970 2432778; facsimile 9702456933.