Transmission of plague by small mammals at Badlands National Park

Science Center Objects

Plague was first detected in the southwest corner of Badlands National Park (BADL), and spread northeastward, reaching the northeast corner in 2011. Multiple prairie dog colonies in BADL and Conata Basin have had population collapses from plague since its arrival in the park. Plague is now common throughout BADL (NPS and USFS, unpublished data), and threatens efforts to preserve and manage the federally endangered black-footed ferret in BADL, which were reintroduced into the park in 1994.

Image: Black-Tailed Prairie Dog ( Cynomys ludovicianus )

Black-tailed prairie dog from the prairie dog town colony at Buffalo Gap National Grasslands. Public domain.

Although plague management in BADL and elsewhere has specifically targeted black-footed ferrets and prairie dogs, this disease is transmitted within a larger community of small mammals. This study will serve as an exploratory effort to gain insight into which species of small mammals and their fleas are primary participants in the plague cycle; which are secondary participants, and which are bystanders. We will conduct a field experiment based on a randomized complete block design to investigate whether small mammals are chronically affected by enzootic levels of plague and which are potential hosts that may function as short-term reservoirs in the flea-borne transmission of plague in black-tailed prairie dog colonies and surrounding environments in BADL.

Our study will encompass a minimum of six consecutive months in two randomly selected paired dog colonies (study sites) that experienced an epizootic plague outbreak in 2011-2012. Within the two colonies, we will utilize three experimental treatment groups on 2.25-ha plots. One plot will receive deltamethrin insecticide applications to control the fleas that are vectors for plague, all animals will be vaccinated with an experimental plague vaccine on a second plot, and the third plot will not be treated. We will capture and mark small mammals on all plots on a monthly basis. Survival during the resulting 5 intervals (based on 6 trapping sessions) will be analyzed for each species via multiple logistic regression and Cormack-Jolly-Seber models in program MARK. By doing the above items, we will be able to determine the role of small mammal species in maintenance of enzootic plague, determine whether small mammal species harbor fleas that carry the bacterium (Y. pestis) and function as short-term reservoir hosts of plague, and assess efficacy and longevity of deltamethrin insecticide for plague vector control on small mammals.