Utah Prairie Dog (Cynomys parvidens)
Status of species: Federally listed as threatened
Distribution: Extreme southwestern Utah General
Description: Utah prairie dogs inhabit the mixed-grass, high elevation prairies of the Rocky mountains in southwestern Utah and are among the smallest members of the genus Cynomys. They are one of only two prairie dog species with federal protection, and estimates were below 1,500 individuals in the 1970’s. After widespread mortality from introduced plague in several major populations was hindered, censuses stood at about 4,000 individuals. Seldom publicized or seen in zoos, extermination occurred after the settlers of Utah labeled them as agricultural pests. Utah prairie dogs are assumed to have diverged from white-tailed prairie dogs, perhaps because of changes in climate and vegetation, as they are close relatives genetically.
Utah prairie dog pups emerge from their underground natal burrows after a five-week lactation period. Only a few pups reach adulthood each year.
Photo by Theodore G. Manno.
Behavior: Like other prairie dogs, Utahs live in aggregations called colonies, which are sometimes divided into wards by topographical features. However, very few populous colonies now exist, and many Utah prairie dogs now live in small, fragmented aggregations. There is substructure within their colonies from family groups (called “clans”) consisting of female kin clusters, the young of the year, and one or two non-reproductive males that are closely related to the females. These groups are not as tightly knit as black-tailed coteries, as there is less interaction (such as kissing or sniffing), more common splitting or joining of groups, more dispersal to different areas during the day for feeding, and routine mating of females with multiple males. Utah prairie dogs hibernate from October to early March.
Females become sexually mature at one year of age and usually stay in the clan of their birth. Males become sexually mature at one or two years of age, and usually disperse from the clan in which they were born (which probably functions to hinder inbreeding). During the breeding season (late March to early April), reproductive males compete through territorial displays and fighting to become the sole male associated with particular coteries of females, often in several feet of snow.
Females can mate one day a year, and males will fight and surround her for the opportunity to copulate. The breeding female will usually mate with the male associated with her clan first, but multiple mating is not uncommon (i.e., more common than in black-tailed prairie dogs). The male occasionally gives a mating call before insemination, and mating pairs copulate both below and above the ground.
As in other prairie dogs, communal nursing between females in a clan occurs during lactation. Juveniles emerge from their mother’s nursery burrow five weeks after their birth, and progressively travel farther from the burrow each day thereafter to feed. The usual litter size is three or four young. It is not yet known whether mothers can easily discriminate between their own and others’ offspring in the clan.
Utah prairie dogs have a complicated defense system which is not yet defined. They have a distinct alarm call for aerial and ground predators, and spot predators by scanning beyond their immediate vicinity. Like black-tailed prairie dogs, the presence of other individuals in the colony and clan is helpful when scanning for predators, as predators are more likely to be detected and each individual can spend less time scanning than if alone. Amazingly, Utah prairie dog males practically never call during attacks, and this oddity is being studied further. Utahs also use scanning to look for possible mates and to defend their territory. Questions such as whether Utah prairie dogs call to warn kin and if there is a risk involved in drawing a predator’s attention with noise will be tested soon.
Utah prairie dogs do not give a jump-yip or an “all-clear” call, nor does any other species of prairie dog except black-tails.
Utah prairie dogs often breed during late March in several feet of snow. Grass (and relief from hunger) starts to reappear in mid-April.
Photo by Elaine Miller Bond.
Members of clans cooperate in ways that are unrelated to predation deterrence. The burrow system is an excellent example. Males often help females collect nesting material to build their nursery burrows. Burrows are all interconnected within a clan, and built with several escape routes for clan members. All females appear to help with the rearing of juveniles in the clan, through burrow construction, scanning for predators, and communal nursing.
Utah prairie dogs are not as infanticidal as black-tails, but males do sometimes kill juveniles before they have emerged from their nursery burrows. The killers are often non-reproductive males that invade clans, but some reproductive males have been observed killing juveniles in areas where they copulated. In contrast to all other prairie dogs and ground squirrels, Utah prairie dog females are not known to protect their nursery burrow through aggression or scanning for potential killers. Whether infanticide helps males gain sustenance or compete favorably with their neighbors is unknown.
Cannibalism also occurs if an individual dies above ground.
Ecological Information: Predations by goshawks, foxes, badgers, and ravens have been observed. Males are particularly vulnerable if they are unable to associate with a clan of females quickly, as are females if they become pregnant. Utah prairie dogs eat grasses and brush, and typically do not have tall grasses in their colonies. Although surveys have often found that very little of Utah’s land is suitable for agriculture, the eating habits of the Utah prairie dog are often blamed for agriculture losses, and extermination has resulted.
Management Information: Utah prairie dogs are listed as threatened. Most colonies are sparse, fragmented, and outside well-protected lands. Bryce Canyon National Park houses one of a few substantial populations, and observed predations suggest that the colony plays an important role in the ecosystem of the area. Introduced plague has been a source of mortality in many populations, but dusting burrows with flea killing powder has proved to be an effective way of hindering the disease.
Control programs that were initiated by authorities in the 1920’s resulted in widespread persecution that was based on the assumption that the species damaged rangeland. By the 1970’s, only 37 colonies existed and it appeared that Utah prairie dogs would be extinct by the year 2000. The species was then listed as endangered in 1973 and reclassified as threatened in 1984 after some minor recovery. Colonies at Bryce Canyon were reestablished in 1974, and the park now protects a few major populations. Present counts of how many Utah prairie dogs are in existence are varied and controversial. Only several hundred are known to exist in Bryce Canyon National Park and its adjacent protected lands.
- Bryant, R. 1996. Prairie dogs at Bryce Canyon. Bryce Canyon Resource Management Files, National Park Service-Bryce Canyon National Park, Utah.
- Crockerbedford, D.C., and J.J. Spillet. 1977. Home ranges of Utah prairie dogs. Journal of Mammalogy 58:672-673.
- Egoscue, H.J., and E.S. Frank. 1984. Burrowing and denning habits of a captive colony of the Utah prairie dog. Great Basin Naturalist 44:495-498.
- Graves, R.A. 2001. The prairie dog: Sentinel of the Plains. Texas Tech University Press, Lubbock.
- Goodwin, H.T. 1996. Pliocene-Pleistocene biogeographic history of prairie dogs, genus Cynomys (Sciuridae). Journal of Mammalogy 77:407-411.
- Haynie, M.L., R.A. Van den Bussche, and J.L. Hoogland. 2003. Parentage, multiple paternity, and breeding success in Gunnison’s and Utah prairie dogs. Journal of Mammalogy 84:1244-1253.
- Hoogland, J.L. 2001. Black-tailed, Gunnison’s, and Utah prairie dogs all reproduce slowly. Journal of Mammalogy 82:917-927.
- Hoogland, J.L., S. Davis, S. Benson-Amran, D. Labruna, B. Goossen, and M.A.
- Hoogland. 2004. Pyraperm kills fleas and halts plague among Utah prairie dogs. Southwestern Naturalist 49:376-383.
- Hoogland, J.L., K.E. Cannon, L.M. DeBarbieri, and T.G. Manno. Predators of Utah prairie dogs target immigrants, breeding males, and pregnant females. In preparation.
- Lehmer, E.M., and D.E. Biggins. 2005. Variation in torpor patterns of free-ranging black-tailed and Utah prairie dogs across gradients of elevation. Journal of Mammalogy 86:15-21.
- Manno, T.G. Why are Utah prairie dogs vigilant? In review.
- Ritchie, M.E. 1999. Biodiversity and reduced extinction risks in spatially isolated rodent populations. Ecology Letters 2:11-13.
- Stebbins, G.J. 1971. The current and present status of the Utah prairie dog in Bryce Canyon. Bryce Canyon Resource Management Files, National Park Service-Bryce Canyon National Park, Utah.
- Written by Theodore G. Manno (PhD student, Auburn University) and Elaine Miller Bond (http://elainebond.home.comcast.net)