White et al. (2005) estimated the area occupied by “active” colonies of black-tailed prairie dog (Cynomys ludovicianus) in Colorado as 255,398 ha (95% CI of±9.5%) based on data collected with aerial transect surveys during 2001–2002 by staff of the Colorado Division of Wildlife (CDOW). During 2004 we conducted on-the-ground examinations of a sample of the colony intercept data used by White et al. (2005) and found evidence of misclassifications that would yield significant overestimation bias. We found that 25.4% of the total length of the colony intercepts we examined was incorrectly classified as being a prairie dog colony (these segments had no prairie dog burrows of any age). We also found that 50.3% of the length of examined intercepts fell on currently inactive colonies or portions of colonies (vacant burrows but no living prairie dogs) and only 24.3% fell on active prairie dog colonies with signs of living prairie dogs at our examinations 2 years after the survey reported by White et al. (2005). Further, in Bent and Kiowa counties, where plague (Yertsina pestus) and poisoning were active, we examined 36.9 km of reported active prairie dog intercepts and subjectively classified only 1.6% as active at normal-appearing prairie dog densities. Our fieldwork demonstrated that the estimate by White et al. (2005) was based on data with substantial errors as well as overestimation biases that will be repeated if protocols are not modified for future surveys.
Black-tailed prairie dogs