Use of environmental sites by mule deer: a proxy for relative risk of chronic wasting disease exposure and transmission

Prions that cause chronic wasting disease (CWD) in cervids can remain infective for years outside the host. Infectious cervids shed prions for a long time, consequently depositing prions in frequently used areas. These environmental prions are important in CWD epidemiology. Unfortunately, effective tools for quantifying CWD prions in soil, water, and other environmental sources are not currently available. Our goal was to investigate relative differences in visits by mule deer (Odocoileus hemionus hemionus) to various environmental site types as an indicator of the relative risk of prion contamination and disease transmission. For this, we deployed a system of triggered-by-movement cameras at eight site types in a CWD-endemic area in Saskatchewan, Canada. We first assessed whether the relative differences among site types in the frequency of visits by mule deer of any sex-and-age class, males, and females varied by season and site type. We then assessed whether the rate of behaviors wit...