Black-Tailed Prairie Dog Colony Connectivity And The Spread Of Sylvatic Plague
Tammi L. Johnson, Kansas Cooperative Fish and Wildlife Research Unit, Division of Biology, Kansas State University, Manhattan, KS 66506; (785) 313-0242; FAX (785) 532-7159; tjohnson@ksu.edu
Jack F. Cully, Jr., US Geological Survey and Kansas Cooperative Fish and Wildlife Research Unit, Division of Biology, Kansas State University, Manhattan, KS 66506
The black-tailed prairie dog (Cynomys ludovicianus) inhabits <2% of its historic range, having suffered significant reductions resulting from habitat loss/fragmentation, poisoning, and sylvatic plague (Yersinia pestis). Sylvatic plague causes nearly 100% mortality and is the only known source of large die-offs in prairie dogs. We mapped black-tailed prairie dog colonies on five national grasslands with a history of plague in 1999, 2001, 2002, and 2003, to document colony changes related to plague. Our research demonstrated that the effects of plague varied among grassland systems. Records indicate widespread die-off of colonies on the Comanche and Thunder Basin National Grasslands in the presence of plague. Conversely, die-offs of isolated colonies were observed on the Cimarron each year and have been observed on the Kiowa and Rita Blanca in 2002 and 2003. These die-offs have not spread extensively to neighboring colonies, as was the case at the Comanche and Thunder Basin National Grasslands. All grasslands had similar colony complex structure, however, topographic characteristics of the grasslands vary. The most striking difference among grasslands was a strong association of colonies on the Comanche and Thunder Basin with dry creek drainages. Dry creek drainages were identified by Roach et al. (2001) as the most likely paths followed by dispersing prairie dogs. We believe the association of colonies with dry creek drainages at Comanche and Thunder Basin may facilitate the intercolony transmission of plague as prairie dogs move to neighboring colonies. Where the infected colony is not associated with a drainage, plague is less likely to spread to neighboring colonies and is therefore expected to cause only local extirpation of colonies.