This species is limited to the high mountain valleys and plateaus in the southern Rocky Mountains, and it is found at elevations of 1,830 to 3,660 m (Pizzimenti and Hoffmann 1973). Its distribution centers around the Four Corners region where the states of Utah, Colorado, New Mexico, and Arizona meet (Pizzimenti and Hoffmann 1973). The northernmost population of C. gunnisoni is found in South Park, CO, while the southernmost population resides near the Mogollon Mountains in southwestern New Mexico (Pizzimenti and Hoffmann 1973).

Biogeographic Regions: nearctic (Native )

endemic to a single nation

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (250-20,000 square km (about 100-8000 square miles)) Range extends from central Colorado to central Arizona, including a small portion of southeastern Utah and much of the northwestern half of New Mexico. The montane and prairie portions of the range are separated by mountain ranges that almost completely limit prairie dog movement between them (USFWS 2008). See Goodwin (1995) for a review of the biogeographic history of prairie dogs.

Gunnison's prairie dog is a stout-bodied creature whose total length varies from 309 to 373 mm (Pizzimenti and Hoffmann 1973). Males are larger than females on average, and subspecies differ slightly in color and size (Pizzimenti and Hoffmann 1973). The dorsal pelage of these animals is yellowish buff intermixed with blackish hairs, while the top of the head, sides of the cheeks, and eyebrows are noticeably darker than the other portions of the pelage (Pizzimenti and Hoffmann 1973). Two annual molts occur in these animals-- one in the spring and another in the fall (Pizzimenti and Hoffmann 1973). The spring molt begins anteriorly and proceeds posteriorly until the tail hair is renewed (Pizzimenti and Hoffmann 1973). In contrast, the winter coat renewal, which is usually complete by mid-September, begins in the posterior region of the body and progresses anteriorly (Pizzimenti and Hoffmann 1973). Cynomys gunnisoni has a much shorter tail - 39 to 68 mm - than other prairie dogs, and it is uniquely colored (Pizzimenti and Hoffmann 1973). The proximal half of the tail is the same color as the dorsal pelage; however, the distal half is grayish with grayish-white hairs appearing at the terminus (Pizzimenti and Hoffmann 1973). This character is very useful in differentiating C. gunnisoni from other white-tailed species, which possess pure white hairs on the distal half of their tails (Pizzimenti and Hoffmann 1973).

It should be noted that one of the most interesting physical characteristics of these animals is the placement of their eyes (Pizzimenti and Hoffmann 1973). Their eyes, positioned on the sides of the head, appear to be adapted for detecting movement over a wide arc, and this allows these prairie dogs to detect predators with greater success (Pizzimenti and Hoffmann 1973).

Average mass: 900 g.

Length: 36 cm

Weight: 1125 grams

• Terrestrial

Compared to the habitats of other prairie dog species, the habitat of C. gunnisoni varies greatly with respect to topography and vegetation (Pizzimenti and Hoffmann 1973). In addition, the burrow systems of C. gunnisoni are more similar to those of ground squirrels than they are to other species of prairie dogs (Pizzimenti and Hoffmann 1973). Entrances are usually located on slopes or small hummocks rather than in depressions, which protects the burrows from flooding (Pizzimenti and Hoffmann 1973). The older burrow systems are deeper, have more entrances at the surface, and more bifurcations below (Pizzimenti and Hoffmann 1973). Usually, each burrow contains a single nest composed of dried vegetation, and there is no evidence that C. gunnisoni uses its burrow for food storage (Pizzimenti and Hoffmann 1973).

Terrestrial Biomes: savanna or grassland ; forest

Comments: High mountain valleys and plateaus at elevations of 1,830-3,660 meters; open or slightly brushy country, scattered junipers and pines. Mainly in areas with high abundance of native plants in northern Arizona (Slobodchikoff et al. 1989). Burrows usually on slopes or in hummocks.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

The masticatory muscles among members of the genus Cynomys are, proportionally, the stoutest and most highly developed among the Nearctic Sciuridae, and the crown height of their cheekteeth equals or exceeds that of all other Nearctic Sciuridae (Pizzimenti and Hoffmann 1973). These characteristics reflect the adaptation of Gunnison's prairie dogs to an almost exclusively graminivorous diet (Pizzimenti and Hoffmann 1973). In addition, analyses of the stomach contents of Gunnison's prairie dogs have shown that these creatures also eat forbs, sedges, and shrubs (Pizzimenti and Hoffmann 1973).

Comments: Diet includes on grasses, forbs, sedges, and shrubs. Insects are of minor importance. This species is not known to store food in its burrow. In Arizona, it feeds mainly on dead grass and seeds in spring and fall, on growing vegetation in summer (Shalaway and Slobodchikoff 1988).

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

100,000 to >1,000,000 individuals

Comments: Population size is very large. In Arizona, each of two colonies studied by Travis et al. (1997) was estimated to include several thousand individuals.

Colonies often are smaller than those of other species; may consist of fewer than 50-100 individuals. Colonial groups are organized into territories that generally contain one adult male, one or more adult females, nonbreeding yearlings, and young of the year; overlap between areas of high use is low between members of neighboring territories (Travis and Slobodchikoff, 1993, Can. J. Zool. 71:1186-1192). Hoogland (1999) also described social organization.

Survivorship is low: only about 50 percent of females that emerged from burrows as juveniles are alive at the end of their first year, and less than 15 percent are alive at the end of their second year (Hoogland 2001).

Major mortality factors are disease, predation, and humans. Colonies suffer drastic population declines and are often extirpated during outbreaks of flea-borne sylvatic plague (Rayner 1985; see also papers by Barnes, Cully, and Fitzgerald in Oldemeyer et al. 1993). This species and Cynomys ludovicianus occur at densities up to 10 times higher and are more social than Cynomys leucurus, and thus they are much more susceptible to the fast spread of plague; in fact, C. gunnisoni is perhaps the most susceptible (Cully and Williams 2001).

This prairie dog is an important prey species in fall for migrating raptors in northern New Mexico (Cully 1988).

Comments: Individuals exhibit periods of inactivity during winter, which may last several months; hibernation may occurs in some parts of the range. In northern Arizona, activity occurs mostly March-October (Shalaway and Slobodchikoff 1988). During spring and summer, most activity occurs in early morning and late afternoon (Pizzimenti and Hoffmann 1973).

The onset of reproduction is somewhat variable and dependent on latitiude, elevation, and seasonal variation (Pizzimenti and Hoffmann 1973). Females are capable of reproducing at 1 year of age and bear a single litter per year (average size is 4.78 young) after a 30 day gestation period (Pizzimenti and Hoffmann 1973). Previous studies have shown that parturition occurs between the months of April and early May (Pizzimenti and Hoffmann 1973). Young remain underground for about a month after birth (Pizzimenti and Hoffmann 1973). Consequently, little is known about growth and development during this period (Pizzimenti and Hoffmann 1973). During the lactation period newborns nurse from one of five pairs of mammae-- two pectoral and three inguinal (Pizzimenti and Hoffmann 1973). After the young begin emerging from the nesting burrow, nursing soon ends, and the offspring must become independent and feed on surrounding vegetation (Pizzimenti and Hoffmann 1973). After all the offspring are weaned, the mother leaves them in the nesting burrow and establishes herself in another burrow (Pizzimenti and Hoffmann 1973). Soon thereafter, the young leave the nesting burrow and disperse to other unoccupied burrows (Pizzimenti and Hoffmann 1973). Males of this species have a baculum which resembles that of ground squirrels (genus Spermophilus), and therefore, males are often described as spermophile-like (Pizzimenti and Hoffmann 1973).

Average gestation period: 30 days.

Average number of offspring: 4.4.

Average age at sexual or reproductive maturity (female)

Sex: female: 365 days.

Only one litter is produced per year, and only about one-fourth of males copulate as yearlings (Hoogland 2001). All females copulate as yearlings (Hoogland 2001). Seasonal timing of onset of reproduction varies somewhat with latitude, elevation, and year. Gestation lasts about 30 days. Litter size averages about 6, but for those females that are successful in weaning offspring, an average of only 3.8 young per female emerge from the nursery burrow (Hoogland 2001). The probability of weaning a litter each year is 82 percent (Hoogland 2001). Parturition occurs in April or early May in northern Arizona (Shalaway and Slobodchikoff 1988). Young stay underground for about 1 month.

Most deaths of Gunnison's prairie dogs can be attributed to predators, disease, and disturbance by man (Pizzimenti and Hoffmann 1973). Predators include such animals as badgers, coyotes, weasels, and several species of raptors, and an occasional pup may be lost to the rattlesnakes that often inhabit the burrow systems of C. gunnisoni (Cully 1991 and Pizzimenti and Hoffmann 1973). Concerning disease, C. gunnisoni carries several types of ectoparasites such as fleas and ticks, and these fleas can carry Yersinia pestis - the causative agent of plague - to which both men and Gunnison's prairie dogs are susceptible (Cully 1991 and Pizzimenti and Hoffmann 1973). Disturbance by man is without a doubt the greatest danger to C. gunnisoni (Pizzimenti and Hoffmann 1973). Extermination programs implemented at the turn of the century have greatly reduced the numbers and the range of Gunnison's prairie dog via such methods as drowning or treatments with carbon bisulfide, strychnine, or fluoride compound 1080 (Pizzimenti and Hoffmann 1973). Fortunately, however, these animals have been given protection in some areas such as the Blue River Reservoir in Gunnison County, CO (Pizzimenti and Hoffmann 1973).

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Intrinsic Vulnerability: Moderately vulnerable

Comments: Reproductive rate is low, relative to other rodents, and survivorship is low (Hoogland 2001), but population size of individual colonies nevertheless may increase rapidly from year to year (Travis et al. 1995, Cully 1997).

Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.

Other Considerations: The Great Plains ecosystem evolved with bison, prairie dogs, and fire as major forces/processes; bison and fire are effectively gone, and the prairie dog is vastly reduced. Litke the Black-tailed Pairie Dog, Gunnison's Prairie Dog is a keystone species upon which many other prairie species depend, but now "may be as functionally extinct as the bison" (M. Gilpin, pers. comm. in Miller and Cully 2001). Black-footed ferret (Mustela nigripes, G1) is almost completely dependent on prairie dogs for food. Mountain Plover (Charadrius montanus, G2), Burrowing Owl (Speotyto cunicularia, G4), Ferruginous Hawk (Buteo regalis, G4), and swift fox (Vulpes velox, G3) are among those animals that are found in greatest numbers on prairie dog towns.

Global Short Term Trend: Relatively stable to decline of 30%

Comments: Relative to the large decline from historical levels, populations may have been more stable in some states in recent decades (USFWS 2006).

Global Long Term Trend: Decline of 30-70%

Comments: Populations in all states within the range have declined significantly compared to historical levels (USFWS 2006).

Between 1916 and 1961, range-wide historical habitat occupied by the Gunnison's prairie dog declined from approximately 97,000 square kilometers to approximately 4,064 square kilometers (USFWS 2008). Between 1916 and the present, habitat occupied by Gunnison's prairie dog throughout its range declined from approximately 97,000 square kilometers to 1,360-2,000 square kilometers (USFWS 2008). This represents a range-wide decline of greater than 95 percent.

Recent data indicate that approximately 3.6 percent of potential Gunnison's prairie dog habitat is occupied in the montane portion of the range, as compared to 18.3 percent occupancy in the prairie portion of the range (USFWS 2008).

In Arizona, Wagner et al. (2006) found that most Gunnison's prairie dog colonies identified as active in initial surveys (1987, 1990-1994, 1998) did not persist to the time of recent surveys in 2000 and 2001; just 82 (30%) of the 270 colonies identified in the initial surveys were still active.

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: USFWS (2008) concluded that "of all the factors affecting Gunnison's prairie dog populations, sylvatic plague is the most significant." Sylvatic plague is an often-fatal bacterial disease that is generally transmitted among rodents by fleas. It is not native to North America and was first detected in Gunnison's prairie dog in New Mexico in 1938 (Link 1955). Plague epizootics can severely reduce or extirpate populations within a short time frame (3 to 10 years) (Lechleitner et al. 1962, 1968; Fitzgerald and Lechleitner 1974; Rayor 1985; Cully et al. 1997; USFWS 2008). Major populations are separated from each other by mountain ranges and large rivers, which preclude repopulation after plague epizootics (USFWS 2008). Habitat loss and degradation, shooting, and inadequacy of existing regulatory mechanisms, were not regarded by USFWS (2008) as significant threats. Although poisoning of Gunnison's prairie dogs and the effects of climate change in the montane portion of the range were regarded as issues important to monitor, USFWS (2008) concluded that aside from plague "no other natural or manmade factors are a significant threat to this species, at this time, throughout all or a significant portion of its range."

Plague is primarily a bacterial disease of rodents, often spread through flea bites or contact with the tissues of infected individuals. It has a long history in Asia and has been present in the United States since 1900.

"Flea-born plague occurs in regular outbreaks and causes population declines and extirpations. Because the disease has only been present within the species' range for approximately 70 years, there has been very little time for resistance to evolve. It is believed that prairie dogs are highly susceptible to plague because of high population densities, abundant flea vectors, and uniformly low resistance. Partial or complete recovery following population reductions due to plague have been reported for both white-tailed and black-tailed prairie dogs, but little to no recovery to previous levels has been noted in montane Gunnison's prairie dog colony die-offs, even after long periods of time."

"The landscape in the montane portion of the Gunnison's prairie dog range is characterized by fewer, smaller, and more isolated colonies with minimal to no metapopulation structure. These factors make the prairie dogs in this habitat highly susceptible to plague-related declines. Gunnison's prairie dogs also commonly forage outside of their home territory which may contribute to the communicability of plague.

"Gunnison's prairie dog populations in the moister montane areas have been widely and severely affected by plague. This may be due in part to higher levels of spring moisture which increases flea numbers, and in turn, plague outbreaks. Although documented population declines due to plague also occur in the drier prairie portions of the Gunnison's prairie dog range, evidence shows that many of these populations recover more rapidly from plague outbreaks probably due to the availability of nearby colonizers.

"After assessing the best available science, the Service has concluded that the Gunnison's prairie dog is not in danger of extinction or likely to become endangered throughout all of its range; however, within the montane habitat in central and south-central Colorado and north-central New Mexico, the species is likely to become threatened or endangered within the foreseeable future due to plague. Based on the continued presence of plague and its effects and the average to maximum life span of Gunnison's prairie dogs, the foreseeable future has been determined to be the year 2042."

Restoration Potential: Davidson et al. (1999) discussed a reintroduction onto a former colony in New Mexico.

Management Requirements: Benefits from management of grasslands to favor native species (Slobodchikoff et al. 1989).

See Oldemeyer et al. (1994) for information on the management of prairie dog complexes for the reintroduction of black-footed ferret.

Management Research Needs: See Miller et al. (in Oldemeyer et al. 1993) for a list of questions for management and research, related to ferret reintroduction, in priority order in each category of disease, habitat management, population dynamics, and public relations.

Biological Research Needs: More information is needed on the impacts of disease, specifically sylvatic plague, and on population status and trends (USFWS 2006).

More information is needed on the impacts of fragmentation and isolation with regard to persistence of prairie dog populations and on the magnitude of the potential threat posed by increasing oil and gas development (USFWS 2008).

Global Protection: Unknown whether any occurrences are appropriately protected and managed

Comments: USFWS (2008) determined that approximately 22 percent of the potential habitat occurs on private lands, 12 percent on State lands, 17 percent on Federal lands, and 49 percent on Tribal lands/Bureau of Indian Affairs (BIA).

Needs: Protect existing colonies from poisoning. Protect several acres/colony.

Cynomys gunnisoni is considered an agricultural pest and economically deleterious because of its tendency to burrow in lands used for farming (Pizzimenti and Hoffmann 1973).

Although C. gunnisoni is primarily a graminivorous species, it has been known to consume small quantities of insects such as grasshoppers and beetles (Pizzimenti and Hoffmann 1973). Therefore, it may play a role in the maintenance of insect populations in certain farming communities and help reduce insect-related crop damage.

Species Impact: Reintroduction of prairie dogs had no observable influence on the resident small mammal and plant connunities in the short-term, but their influences may be more evident over the long-term (Davidson et al. 1999).

Comments: Researchers have come to different conclusions regarding the taxonomic status of the two nominal subspecies (gunnisoni and zuniensis). Pizzimenti (1975) examined variation in cranial and external characteristics and suggested that C. cunnisoni begregarded as a montypic species. Hoffmeister (1986) questioned Pizzimenti's analyses and conclusions, and he stated that "it appears there are size and proportional differences between prairie dogs that can be called C. g. gunnisoni and C. g. zuniensis, but the area of intergradation between the two may need redefining." Hoffmeister (1986) also stated that "some workers may prefer to regarded this subspecies [C. g. zuniensis] as indistinguishable from C. g. gunnisoni." Unpublished research by Hafner (cited by USFWS 2008) indicates that the distribution of mtDNA haplotype lineages supports past geographic isolation, followed by limited mixing in regions coincident with the recognized borders of the two purported subspecies. USFWS (2008) avoided the subspecies issue and instead distinguished "montane" and "prairie" populations whose distributions are essentially the same as those of the subspecies gunnisoni and zuniensis, respectively.

Based on information from two colonies 13 kilometers apart in Arizona, Travis et al. (1997) determined that this species exhibits low within-population genetic diversity and significant differentiation between colonies.