Spatial and temporal use of a prairie dog colony by coyotes and rabbits: Potential indirect effects on endangered black-footed ferrets

Abstract

In western North America, endangered black-footed ferrets Mustela nigripes are conserved via reintroduction to colonies of prairie dogs Cynomys spp., their primary prey. Predation is an important source of mortality; coyotes Canis latrans appear to be the most problematic predator, accounting for 67% of known predation events on radio-tagged ferrets. Little is known about what factors affect spatial use of prairie dog colonies by coyotes, or how other animals might affect interactions between coyotes and ferrets. During June-October 2007-2008, we used spotlight surveys to monitor coyotes and ferrets (both years) and rabbits Sylvilagus spp. (first year) on a 452-ha colony of black-tailed prairie dogs Cynomys ludovicianus in the Conata Basin, South Dakota. Coyotes appeared to select areas of the colony used by rabbits, suggesting coyotes hunted rabbits, a common item in their diet. Between midnight and sunrise, ferrets were most commonly observed during early morning (01:00-03:00h), whereas coyotes were observed mostly during dawn (04:00h - sunrise) when ferrets were rarely seen. These temporal differences in the timing of observations suggest ferrets tend to remain underground in burrows when coyotes are most active. Coyotes appeared to be attracted to rabbits in both space and time, suggesting the risk of predation for ferrets might relate to the abundance and locations of rabbits in prairie dog colonies.