Gunnison’s Prairie Dog
Compared to the habitats of other prairie dog species, the habitat of C. gunnisoni varies greatly with respect to topography and vegetation. 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 . Entrances are usually located on slopes or small hummocks rather than in depressions, which protects the burrows from flooding. The older burrow systems are deeper, have more entrances at the surface, and more bifurcations below. 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.
Gunnison’s prairie dog
Gunnison’s prairie dog is a stout-bodied creature whose total length varies from 309 to 373 mm. Males are larger than females on average, and subspecies differ slightly in color and size. 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. Two annual molts occur in these animals– one in the spring and another in the fall. The spring molt begins anteriorly and proceeds posteriorly until the tail hair is renewed. In contrast, the winter coat renewal, which is usually complete by mid-September, begins in the posterior region of the body and progresses anteriorly. Cynomys gunnisoni has a much shorter tail – 39 to 68 mm – than other prairie dogs, and it is uniquely colored. 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. 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. It should be noted that one of the most interesting physical characteristics of these animals is the placement of their eyes. 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.
Reproduction
The onset of reproduction is somewhat variable and dependent on latitude, elevation, and seasonal variation. 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. Previous studies have shown that parturition occurs between the months of April and early May. Young remain underground for about a month after birth. Consequently, little is known about growth and development during this period. During the lactation period newborns nurse from one of five pairs of mammae– two pectoral and three inguinal. After the young begin emerging from the nesting burrow, nursing soon ends, and the offspring must become independent and feed on surrounding vegetation . After all the offspring are weaned, the mother leaves them in the nesting burrow and establishes herself in another burrow. Soon thereafter, the young leave the nesting burrow and disperse to other unoccupied burrows. Males of this species have a baculum which resembles that of ground squirrels (genus Spermophilus), and therefore, males are often described as spermophile-like.
Behavior
Cynomys gunnisoni is often found in semi-social aggregations; yet, colonies of these mammals are generally smaller than those of other species of prairie dogs and usually consist of fewer than 50 to 100 individuals. Interestingly, in open habitats where Gunnison’s prairie dogs have been afforded protection, the colonies become quite extensive and densely populated. Overall, the social organization of these creatures is loosely knit and more closely resembles that of ground squirrel aggregations than it does more highly structured organizations of other prairie dogs. Social structure consists mainly of mother-offspring relationships, while adult males live somewhat apart from females and offspring during the post-natal period. Territoriality is rarely exhibited by a male C. gunnisoni; older males may defend a small area near their burrows, but they often feed alongside other members of the colony without conflict. In contrast, a female C. gunnisoni is highly territorial and aggressive during the post-natal period. However, as soon as her pups emerge above ground, the aggressive behavior subsides. Gunnison’s prairie dogs are strictly diurnal, and their greatest periods of activity occur in the early morning and late afternoon. Above ground activities mostly include feeding, playing, and grooming; however, these animals are constantly on the lookout for possible danger while venturing out of their burrows. Cynomys gunnisoni will sit up on its hind feet to survey its surroundings from the tops of the dirt mounds that form at burrow entrances. Although several physical attributes can be used to distinguish C. gunnisoni from other species of prairie dogs, vocalizations – particularly alarm barks – are species specific and permit identification. Besides the alarm call, which consists of a series of repetitive barks, C. gunnisoni is capable of generating four other calls: raspy chatter, a contact call given under peaceful surroundings; a snarl or rasp, an aggressive call; a growl, another aggressive call; and a scream, an injury or escape call. A study of the alarm calls of adult C. gunnisoni from three separate Arizona towns during April-September 1977 uncovered some very interesting facts. First, the alarm calls of Gunnison’s prairie dog have diverged into local dialects and therefore differ between the three studied locations. Second, within a particular C. gunnisoni colony there were significant differences in the calls announcing the presence of different predators — the different predators used in the study were humans, dogs, coyotes, and hawks. In addition, a significant difference in calls existed when the same predator was announced in different colonies. Third, the number of syllables and the total call length were strongly correlated with the complexity of the habitat– the more complex the habitat was in terms of vegetation, rocks, and tree stumps, the longer the call became and the more syllables it contained. This phenomenon may be explained by the fact that sound attenuates faster in a more complex habitat, and a longer call with a larger number of syllables may be needed in a more complex habitat to maintain the same alarm function as a shorter call in a less complex habitat. Above ground activity of C. gunnisoni occurs between late March and October, and the winter months comprise a period of inactivity for C. gunnisoni in most locations. Snowfall forces many of these creatures to remain underground and to survive off the fat stores they developed over the summer months. There is little evidence regarding hibernation in these animals, but periods of inactivity, which may last several months, support the contention that Gunnison’s prairie dogs hibernate, at least in the colder parts of their range. Additional evidence supporting this claim comes from a laboratory colony observed during the winter months, in which members entered short periods of deep sleep with low food intake. No information regarding the body temperature of prairie dogs in the wild during the winter months is currently available, however.
Food Habits
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. These characteristics reflect the adaptation of Gunnison’s prairie dogs to an almost exclusively graminivorous diet. In addition, analyses of the stomach contents of Gunnison’s prairie dogs have shown that these creatures also eat forbs, sedges, and shrubs. In captivity they should be offered a complete diet of rodent lab blocks, and rat or mouse mix, with bits of fruit or veggies regularly. Cheerios or wheat bread are great treats, in small quantities. Do NOT feed chocolate, fried foods, salted foods, candy or junk food! They may enjoy crickets and mealworms if they are captive bred, never feed wild insects as they may carry parasites. Vitamins, like Nutri-Cal are a good addition to their diet, and added calcium during nursing and growth due to demands on their systems at those times, but take care not to overdo it. Water bottles should be used to proved constant, clean water. Ceramic or stoneware food dishes work well for keeping seeds or fresh foods off the floor, and a wire mesh hopper that allows them to eat the lab blocks through without extra waste.
