Sex-Specific Movements and Habitat Use by Elk in the Cascade Range of Washington

Abstract

I studied sex-specific movements and habitat use of Rocky Mountain elk (Cervus elaphus nelsoni) in the Cascade Range of south-central Washington, USA, during 1992-1999. I used 3,059 relocations of 78 radiomarked elk (25 adult males, 26 subadult males, and 27 adult females). Adult males (≥5 yr) consistently migrated from summer-autumn home ranges earlier than other elk, contrary to expectations, but the timing of spring migration was similar among sex-age classes. Using compositional analysis, I found habitat use of adult and subadult (≤4 yr) male elk during winter and summer-autumn were similar at home-range and patch scales. However, use compositions for cover types and topographic features often differed between males and females. Males selected mature semi-closed forest at both scales during summer-autumn. Females demonstrated similar preferences to males at the home-range scale. I did not detect selective use of cover types at the patch scale by females during summer-autumn. I also did not detect selective use of cover types at the home-range scale by males during winter, but males selected conifer forest at the patch scale. In contrast, females selected oak (Quercus spp.) woodland and openings at the home-range scale and used cover types proportional to their availability at the patch scale during winter. All elk located their winter home ranges in relatively steep terrain, but within winter home ranges, males selected gentler slopes than females did. The effects of roads on habitat use differed among sex-age classes of elk; adult males selected summer-autumn home ranges with lower road densities and used patches much farther from roads than did subadult males (x difference = 693.8 m) and females (x difference = 827.4 m). During winter, female elk home ranges had lower road densities, and females used areas farther from roads than adult and subadult males, but differences in effect sizes were small. Data were consistent with the hypothesis that males used environments with predictably less human activity than did female elk.