Cooperative Fish and Wildlife Research Units Program: all
Education, Research and Technical Assistance for Managing Our Natural Resources

For several decades, chronic wasting disease (CWD) has exhibited an unabated expansion in distribution and intensity across North America. Upon detection, either for the first time in a novel area or in a region with an existing outbreak, wildlife management agencies are tasked with responding to mitigate the disease. This often entails creation or modification of a management zone within which rules and regulations can be modified that support an agency’s disease management plan. To help inform the process of creating an appropriately-sized CWD management zone, assuming that wild deer movements are the primary risk factor for disease spread, we used data from GPS-collared white-tailed deer (Odocoileus virginianus) in southeastern Minnesota and southcentral Pennsylvania to estimate long-distance movements associated with dispersal and migratory behaviors. These contrasting study areas with active CWD outbreaks permit an evaluation of deer movement dynamics in different parts of their range. We quantified the proportion, distribution, timing, and orientation of dispersing and migratory deer. We observed 21% of female and 58% of male yearlings disperse from their apparent natal home range in Minnesota, while in Pennsylvania, 4% of female and 68% of male yearlings dispersed. We also documented 20% of females and 6% of males migrated between seasonal home ranges in Minnesota, while in Pennsylvania, no females and 5% of males migrated. The average distance deer dispersed or migrated in Minnesota was 20 km and 11 km, respectively, while in Pennsylvania deer dispersed or migrated only about 4km. Both sexes in Minnesota tended to disperse in a consisent, westerly direction; however there was no directional preference observed for migratory deer, nor for dispersing deer in Pennsylvania. We found differences in natal and adult home range size for both sexes in Minnesota, but not for males in Pennsylvania. Our results identify the considerable variability in disperal and migration dynamics of white-tailed deer in disparate landscapes, which is important to agencies managing CWD. We summarize the distribution of these long-distance movements and suggest agencies use this information to decide on an optimal management zone size that meets their needs. We encourage the development of formalized assesments of the tradeoffs associated with optimizing decisions about creation of CWD management zones across white-tailed deer populations that exhibit variation in dispersal behavior and caution against an arbitrary size/shape or one-size fits-all approach to creation of disease management zones.