Population Viability Analysis of the Utah Prairie Dog

Roberts, W; Rodriquez, Jon; Good, Tatjana; Dobson, Andrew

Utah prairie dogs (Cynomys parvidens) are sciuromorph rodents endemic to semi-arid grasslands in southwestern Utah. An estimated 95,000 individuals existed in 1920 (McDonald 1993). By the 1960's, however, the species' numbers had been severely reduced by anthropogenic habitat changes, poisoning, plague and drought (USFWS 1991). Populations were restricted to a fraction of the species' former range. In an attempt to forestall imminent extinction, the species was listed as Endangered under the US Endangered Species Act in June 1973. Numbers increased following protection, particularly on private lands. And the UPD was downlisted to Threatened status in May 1984. A long-term recover plan, aimed at securing the future for the UPD, was formally adopted the US Fish and Wildlife Service in 1991 (USFWS 1991). Based on the 1987 recommendations of the World Conservation Union's Captive Breeding Specialist Group (currently Conservation Breeding Specialist group, GBSG), the concrete objectives are to retain 90 percent of the genetic diversity of the species for 200 years. To achieve this, the recovery plan sets the specific target of establishing and maintaining one population each on public lands in the West Desert, Paunsaugunt Area and Awapa Plateau of Utah, each with a minimum of 813 adults in the annual spring census, with animals transferred between populations for gene exchange and managed intensively. In all three recovery areas (Awapa, Paunsaugunt and West Desert), most increases in prairie dog numbers during the last twenty years have occurred on private, not public lands. Recent spring census results show that the UPD population continues to fluctuate over time. To address recent concerns, we have conducted a population viability analysis (PVA) for the Utah prairie dog. Using available information on the demography and population structure of the UPD, we assess the interaction between stochasticity, habitat destruction, catastrophes, and natural recolonization by dispersing individuals.