Sex-Specific Responses of North American Elk to Habitat Manipulation

Abstract

Female and male cervids often use different habitats, and patterns of habitat selection and space use by the sexes may be influenced in part by selection of different forage resources. We tested the hypothesis that female and male ruminants select habitats that differ with respect to quality and abundance of forage by evaluating sex-specific responses of North American elk (Cervus elaphus) to an experimental fuels-reduction program at the Starkey Experimental Forest and Range (Starkey) in northeastern Oregon. From 2001 to 2003, 26 stands of true fir (Abies) and Douglas-fir (Pseudotsuga menziesii) were mechanically thinned and burned, whereas 27 similar stands were left untreated to serve as controls. We used measured differences in forage quality and quantity to predict sex-specific responses to this habitat manipulation. We compared seasonal patterns of habitat selection between the sexes using locations from 48 female and 14 male elk collected during daily periods of peak foraging activity during spring and summer of 2005 and 2006. During spring, females selected 4-year-old burns and used 2- and 3-year-old burns in proportion to their availability, whereas males avoided all fire-treated stands. In addition, control stands were avoided by females but selected by males during spring. During summer, control stands were selected and treatment stands either were avoided or used in proportion to their availability by the sexes. Use of treated stands by female and male elk was influenced by different environmental variables across seasons, but mean overlap of utilization distributions between the sexes was higher in summer than spring. These results indicate that although fuels-reduction treatments at Starkey may have increased foraging opportunities for female elk in spring, those treatments likely were of little benefit to male elk.