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New DNR study links chronic wasting disease prevalence above ~30% to deer population declines
Summary
DNR research presented to the board found that chronic wasting disease (CWD) substantially reduces adult survival and that modeled population growth falls below replacement when CWD prevalence reaches roughly 29–30% in study areas, with implications for long-term deer trends in high-prevalence counties.
Dr. Dan Storm, the DNR’s deer research scientist, presented results from a multi-year study that collared more than 1,000 deer (including 766 GPS-collared adults and over 300 fawns) in a high-prevalence area of southwest Wisconsin to estimate how chronic wasting disease (CWD) affects survival and population dynamics. He described capture methods (net drops, chemical immobilization, GPS collars and rectal biopsy for live testing) and follow-up mortality investigations.
Key findings: Storm said annual survival of uninfected adult females exceeded 80%, while CWD-positive adult-female survival was roughly half that level; modeled results show population growth falls below replacement (population growth rate <1.0) when CWD prevalence reaches about 29% in the study area. He emphasized the disease’s principal effect on adult-female survival and noted local variation in recruitment and other demographic factors, and he said declines are likely in high-prevalence areas in the state’s southwest.
Implications and questions: board members asked about hunter-harvested collared deer, juvenile survival, transmission to offspring and the presence of CWD in other species including elk; staff confirmed CWD has been detected in elk in other states and discussed research on detection assays and movement-data analysis to spot behavior changes that might indicate disease progression. The DNR also emphasized the availability of interactive maps and county-level monitoring data on the department website.
Next steps: Storm said ongoing analyses and additional modeling are under way, including work using collar-movement data to detect behavioral changes that could signal infection, and staff will continue monitoring prevalence and adapt management tools accordingly.
