Estimating Population Densities of Black-Tailed Prairie Dogs

The recent black-footed ferret reintroduction into the Conata Basin area of west­central South Dakota has prompted managers of USDA Forest Service, Buffalo Gap National Grasslands and National Park Service, Badlands National Park, to reassess methods of determining population size of black-tailed prairie dogs Cynomys ludovicianus. Most agencies are currently relying on a protocol developed by Biggins et al. (1993) to assess black-footed ferret habitat, a section of which deals with prey abundance. The protocol is based on population estimates derived from counting the number of active burrows. The justification for this was a set of unpublished data that reported fair and good relationships between counts of active burrows and black- and white-tailed prairie dogs C. leucurus, respectively (Biggins et al. 1993). While there is no other correlative information relative to active burrows, Powell et al. (1994) suggested that counts of active burrows alone may not be a reliable indicator of black-tailed prairie dog populations. Menkens et al. (1988) examined relationships between populations determined by mark-recapture and total burrow counts. They reported that white­tailed prairie dog density was not significantly related to burrow density and was not a useful predictor of population density. However, Fagerstone and Biggins (1986) and Menkens et al. (1990) reported high correlation coefficients when comparing visual counts of white-tailed prairie dogs with mark-recapture densities. The purpose of this study was to examine relationships among population estimates from mark-recapture techniques with visual counts, active burrow counts, and total burrow counts derived by ground and aerial surveys all within the same experimental design