Cynomys parvidens 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Rodentia Sciuridae

Scientific Name: Cynomys parvidens J. A. Allen, 1905
Common Name(s):
English Utah Prairie Dog
Taxonomic Notes: Cynomys parvidens has been regarded as a subspecies of Cynomys leucurus by some authors. Thorington and Hoffmann (in Wilson and Reeder 2005) recognized the two taxa as distinct species.

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(i,ii,iii,v)c(iv)+2ab(i,ii,iii,v)c(iv) ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Linzey, A.V., Rosmarino, N. & NatureServe (Willson, K., Roth, E., Hammerson, G. & Cannings, S.)
Reviewer(s): Amori, G. & Koprowski, J. (Small Nonvolant Mammal Red List Authority)
Listed as Endangered because its extent of occurrence is estimated to be only 1,850 km², and its area of occupancy is estimated to be only 28 km², and there is a continuing decline in the extent and quality of its habitat due to ongoing habitat destruction as well as the number of individuals due to persecution and outbreaks of the plague.
Previously published Red List assessments:

Geographic Range [top]

Range Description:The species' range is restricted to an area of about 1,850 square kilometres in southern Utah in the United States. Prior to control programs, the range reportedly extended from Pine and Buckskin valleys in Beaver and Iron counties (perhaps west to Modena in Iron County), north to at least Salina Canyon and near Gunnison in Sevier County (possibly to Nephi), south to Bryce Canyon National Park, and east to the foothills of the Aquarius Plateau (Collier 1974, Pizzimenti and Collier 1975, McDonald 1997). More recently, this species occurred in substantial populations in only three areas: the Awapa Plateau, along the east fork of the Sevier River, and in eastern Iron County; the grass and Sevier river valleys, plus three small, widely separated mountain valleys have small populations (Collier 1974, Pizzimenti and Collier 1975). The species is scarce or absent in the Aquarius Plateau, Fremont and Paria valleys, and Salina Canyon (Collier 1974, Pizzimenti and Collier 1975). It occurs only in areas at elevations of 1,500 to 2,700 m asl.
Countries occurrence:
United States (Utah)
Additional data:
Lower elevation limit (metres):1500
Upper elevation limit (metres):2700
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Counts by the Utah Division of Wildlife Resources in 2004 yielded a population estimate of approximately 8,000 adults (USFWS, On a broad scale, USFWS (1991) mapped about two dozen subpopulations (distinct patches of occupied habitat).

According to USFWS (1990), the total population increased to 9,200 adults in spring 1989. The range continued to expand in the early 1990s as a result of transplantation and natural population increase; this increase may have resulted from recent mild winters in Utah; population densities in the early 1990s were "increasing to a point where a crash is imminent due to an outbreak of plague" (USFWS 1990). Range-wide spring survey counts conducted by the Utah Division of Wildlife Resources in the spring of 2004 found 4,022 adults, which represents approximately half of the total population. Hence the current population size is similar to that in 1989.

Population in 1920 (before control programs) was estimated at 95,000 (USFWS 1990). Currently the adult population size is thought to be fewer than 10,000. Historical area of occupancy has declined from about 1,800 square kilometers historically to only about 28 square kilometers today.

Population densities are extremely variable, ranging from a mean of less than 2.5/ha to more than 74/ha (Pizzimenti and Collier 1975).

Population in 1920 (before control programs) has been estimated at 95,000 (USFWS 1990). Currently the adult population size is thought to be fewer than 10,000. Historical area of occupancy has declined from about 1,800 square kilometers historically to only about 28 square kilometers today.
Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Habitat consists of grasslands, in level mountain valleys, in areas with deep well-drained soil and vegetation that prairie dogs can see over or through. Prairie dogs dig underground burrow systems, in which the young are born.

They reproduce slowly, relative to other rodents (Hoogland 2001). Females produce only one litter per year, but the probability of weaning a litter each year is only 67% (Hoogland 2001). Although all females copulate as yearlings, only 49% of males do so (Hoogland 2001). For females that wean offspring, mean litter size at first emergence from the nursery burrow is 3.88 (Hoogland 2001). Mating occurs in March or April. Gestation lasts about one month. Young are born in late April or early May. Litter size is 2-10 (average 3-5); female produces one litter per year. Young emerge above ground at six weeks (late May to early June), weaned in about seven weeks, first breed at about two years.

Lives in colonies ("towns"). Colony structure is dynamic in size and location; social units within colony comprise a dominant male, several females, and the young of the past two years (Matthews and Moseley 1990). Survivorship in the first year is less than 50%; only 30% remain alive at the end of their second year (Hoogland 2001).

Feeds primarily on grasses, alfalfa, leafy aster, European glorybind, wild buckwheats in seed, flowers and seeds of shrubs, and insects when available; also may consume cattle faeces; generally prefers flowers and seeds over leaves. The species is inactive and torpid in severe winter conditions. Adults emerge and begin foraging from mid-March to early April, enter dormancy mid-July to mid-August; juveniles enter dormancy from early October to mid-November; low elevation colonies (below 7,000 ft) generally are two weeks earlier than higher elevation colonies (Spahr et al. 1991).

Threats [top]

Major Threat(s): The major historical decline was primarily a result of intensive poisoning efforts. For example, in 1971, poisoning "annihilated" one of the few remaining large colonies (near Loa, Wayne County) (Pizzimenti and Collier 1975). In 1972, the largest colony (Enoch, Iron County) was reduced from more than 1,000 individuals to fewer than 50, apparently from poisoning (Pizzimenti and Collier 1975).

Recent threats include habitat destruction resulting from residential and agricultural development on private lands, deliberate (illegal) poisoning and shooting by ranchers and farmers concerned about agricultural damage, and plague outbreaks (Hoogland et al. 2004). Plague has caused major declines in various populations over the past several decades. Grasslands are becoming dominated by sagebrush due to livestock grazing (K. McDonald pers. comm. 1995); shrubby habitats provide poor conditions for prairie dogs. Drought may reduce prairie dog food resources and cause population declines in colonies on drier sites.

Conservation Actions [top]

Conservation Actions: In 1991, a formal recovery plan for Utah prairie dogs was approved. The bulk of the recovery efforts has centered around the establishment of colonies on public lands by transplanting animals from private lands within their historical range (Hafner et al. 1998). The potential of these efforts to be successful in the long-term have apparently been undermined by reclassification of its status to Threatened (allowing animals to again be eradicated). In 2001, the US Fish and Wildlife Service was petitioned to restore Endangered status. However, no finding has been issued. In March 2004, the petitioners expressed intent to sue over the failure to make a timely finding.

One colony is protected in Bryce Canyon National Park. As of 2004, despite public land efforts at establishing new Utah prairie dog colonies and supplementing existing ones, approximately 68% of Utah prairie dogs still occur on private and other nonfederal lands.

Research needs include: determine causes of high rate of crashes of local populations; determine rangeland revegetation and grazing practices that will result in improved persistence of translocated populations; determine genetic consequences of high rates of population crashes and how this affects the spatial arrangement of translocation sites and numerical goals for population recovery (Utah Prairie Dog Recovery Implementation Team 1997).

Citation: Linzey, A.V., Rosmarino, N. & NatureServe (Willson, K., Roth, E., Hammerson, G. & Cannings, S.). 2008. Cynomys parvidens. The IUCN Red List of Threatened Species 2008: e.T6090A12420124. . Downloaded on 16 October 2018.
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