Gunnison's prairie dog has a diploid number of 40 chromosomes, which is strikingly different from all other species of prairie dogs, who have a diploid number of 50 chromosomes (Pizzimenti and Hoffmann 1973).
Perception Channels: tactile ; chemical
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
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.
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).
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 )
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
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).
Other Physical Features: endothermic ; bilateral symmetry
Average mass: 900 g.
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).
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
Average gestation period: 30 days.
Average number of offspring: 4.4.
Average age at sexual or reproductive maturity (female)
Sex: female: 365 days.
