Early‐life movement ecology of a cervid: Implications for chronic wasting disease management

Abstract Aspects of early‐life movement, including dispersal and exploratory movement, are often poorly understood and are key to disease epidemiology. Chronic wasting disease (CWD), a terminal prion disease impacting cervids, is expanding geographically and presents one of the most important challenges in wildlife disease management. Epidemiological models are often used to guide surveillance and assess management, but knowledge gaps in early‐life movement may limit the reliability of model predictions. Filling this knowledge gap is a critical need for increasing understanding of an important life‐history behaviour that can inform disease modelling and management. We investigated early‐life movement of mule deer ( Odocoileus hemionus ) within a recently developed CWD zone in the Texas Panhandle. We identified excursive movements outside the natal range and categorized them as dispersal and exploratory movements. We examined whether mule deer altered path distances, movement rates and resource selection when on excursive movements. From April 2021 to mid‐February 2022, we observed 121 excursive movements (6 dispersals, 114 exploratory movements and 1 unclassified) in 29 juvenile mule deer. Dispersal was only observed in males, but most (63%) exploratory movements were conducted by females. All individuals moved faster when traversing outside the natal range. Relative to their natal range, male movement rates increased while on a dispersal but were not significantly different from the natal range while on an exploratory movement. Cumulative distances of excursive movement paths ranged from 1.27 to 617.47 km. Resource selection differed between the sexes, and both sexes altered resource selection during excursions. Males exhibited strong selection for proximity to shrubland during excursions and when within their range. For females, selection increased for higher elevation, steeper slopes and greater distance to water during an excursion compared to within range. Practical implication . Our findings suggest that early‐life movement varies greatly between individuals, with differing rates of excursive behaviour and resource selection. Furthermore, exploratory movements occurred 19 times more often than dispersal and occurred throughout all seasons. This study provides insight into the early‐life movement ecology of mule deer that is likely important for many population processes and disease dynamics.