FACTORS AFFECTING CHRONIC WASTING DISEASE PRION TRANSMISSION AMONG WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS) IN SOUTHERN MICHIGAN

The potential for direct and indirect transmission of Chronic Wasting Disease (CWD)-causing prions increases as deer gather, and understanding factors affecting deer space use and grouping behavior can help managers identify areas where deer may congregate in winter. Additionally, deer interactions and behaviors play an important role in direct transmission of prions. My objectives in this study were to identify environmental and landscape features that influence deer group size, and quantify behaviors exhibited by deer at congregation areas including baited sites, food plots, and naturally occurring forage. I used road-based and camera-trapping surveys from January-April 2021 and 2022, throughout a 4,262 km2 area in southern Michigan. On road surveys, I observed 603 deer groups and group sizes ranged from 1 – 67 deer. From trail camera footage, I conducted over 2,000 direct behavioral observations (bait sites = 1,631, food plots = 416). My results indicate that potential areas for larger deer group sizes include larger corn and forage crop fields adjacent to woodlots that are >220m away from buildings. For all deer observed, I detected significantly fewer direct contacts at food plots (βFood plot = -1.45 [95% CI = -2.00 - -0.90]) and transects (βTransects = -1.12 [95% CI = -1.64 – 0.59]) compared to bait sites. I found a lower number of self-contacts at food plots compared to bait sites (βFood plot = -1.14 (95% CI = -1.64 - -0.64). Also, I observed fewer environmental contacts at food plots (βFood plot = -0.68 (95% CI = -0.90 - -0.47) and transects (βTransects = -0.65 (95% CI =-0.87 - -0.43) compared to bait sites. Additionally, direct contacts varied by deer sex and age class at bait sites, including adult males had an increased likelihood of contacts as the number of male fawns present increased (βMale fawns = 0.45 [95% CI = 0.19 – 0.71]). My results indicate that in areas of CWD concern, food plots and naturally occurring forage offer a less risky food source for deer. This information can inform simulation models designed to assess CWD transmission.