Dynamic biogeography of prairie dog (Cynomys ludovicianus) towns near the edge of their range

Despite the broad and relatively stable distribution of the black-tailed pr airie dog (Cynomys ludovicianus) throughout much of the Pleistocene and Hol ocene, anthropogenic activities have reduced the current range of this nati ve grassland species and its associated biotic community to <5% of its hist oric range (approximately 1800-Miller et al. 1990, 1994). We Studied the bi ogeography of the black-tailed prairie dog along the southeastern edge of i ts geographic range with 3 primary objectives: to assess the status of the species in this region and identify trends in town coverage and mean town s ize over the past century, to test whether town persistence was associated with area and isolation of towns, and to assess the protection status of to wns > 10 ha by comparing locations of extant towns to those of protected pu blic lands. Prairie dog towns in this region now represent only 1% of prese ttlement estimates and continue to decline in total acreage because of adva nced agricultural practices, systematic control measures, and outbreaks of plague. Further, <1% of the area now occupied by prairie dog towns > 10 ha occurs within protected locations. As the total coverage of towns has decli ned, mean size of towns has decreased, and towns have become increasingly m ore isolated. Persistence of towns between 1989 and 1997 was highest for th e largest and most isolated towns, even in regions that were not known to b e influenced by plague.