Summer-fall home-range fidelity of female elk in northwestern Colorado: Implications for aspen management

Abstract

Understanding the degree of spatial fidelity exhibited by individuals within a species increases our ability to manage for desired future outcomes. Elk (Cervus elaphus) is a closely managed species in the Western US, but there is little research evaluating their summer home-range fidelity. Elk summer-fall home-ranges overlap considerably with aspen (Populus tremuloides)-dominated forest types, and elk can impact aspen regeneration because it is a preferred browse species. We evaluated the fidelity of 72 adult female elk to individual summer-fall home ranges in northwestern Colorado, USA, during two consecutive summers (1996 and 1997). To compare elk summer-fall home-range overlap and distribution based on individual kernel-estimated utilization distributions, we calculated the volume-of-intersection statistic and the inter-annual distances between centers-of-mass. We found adult female elk in the White River Study area exhibited strong fidelity to individual home ranges. Volume-of-intersection results indicated that 93% of the elk showed explicit home-range overlap between 1996 and 1997, but that all the elk returned to the same vicinity as the previous year (median=0.42, SE=0.02, n=72). Between-year center-of-mass distances ranged from 183m to 34,170m (mean=3819, SE=619, n=72), while within-year maximum distances between location points ranged from 4320m to 31,680m (mean=13,958, SE=628, n=72). Hunting increased the distance traveled by individual elk, but did not change the center of their home-range. Understanding female elk home-range fidelity could influence forest management focused on aspen regeneration. Specifically, targeted removal of female elk from their summer-fall home ranges could create a ‘window of opportunity’ in which browsing pressure was reduced, and the likelihood of aspen recruitment increased.