Abstract - Behavorial and Physiological Responses of Elk to Human Disturbances in the Southern Black Hills, South Dakota
Millspaugh, Joshua J. 1999. Behavorial and Physiological Responses of Elk to Human Disturbances in the Southern Black Hills, South Dakota. PhD Dissertation. University of Washington. 274 p.
I studied the behavioral and physiological responses of elk to human activites, and elk resource selection and movement patterns in Custer State Park (CSP), South Dakota from 1993-1997. Measures of space use sharing between elk and hunters measured by utilization destributions differed among subherds. between bulls and cows, and by hunting season. Hunter density, vegetative cover, secondary road use, and tertiary road density appeared to influence elk response to hunters. Elk utilization distribuions were higher at greater distances from roads, irrespective of available vegetative cover. Tertiary roads gnerelaly impacted elk distributions less than other road types. Temporal variation in elk movements and resource selection indicate that elk response to hunters and roads is adaptive and short-lived. Trails significantly affected elk movements; elk avoided areas < 600m of hiking trails. Mean fecal corticosterone levels (FCL) of bulls and cows were lowest in winter (~17 ng/g bulls, ~20 ng/g cows) and steadily increased to peak levels in summer (~33 ng/g bulls and ~34 ng/g cows). Vehicle use on primary roads, primary road density, and mean temperature were correlated to FCL. Other biological factors (e.g., lactation) did not adequately explain these patterns of corticosterone secretion. My results suggest that fecal glucocoriticoid measures are a potentially powerful tool for assessing disturbances in free-ranging wildlife. Elk resource selection patterns as determined by discrete choice modeling differed by season, time of day, and sex. In summer, fall, and spring, habitat utility was greatest in meadows at night, and greatest in dense timbered stands during the day. Intermediate-density stands (e.g., thinned) provided little utility year round. Winter habitat utility was greatest in open habitats during all time periods. Canopy closure, tree basal area, and temperature were important habitat components determining summer, diurnal bed site selection of elk. Despite the possibility that vegetative cover increases comfort in summer, hiding cover and forage availability are more important habitat components. Home range estimates of CSP elk are 2-5 times larger than other nonmigratory elk populations in forested regions. Custer State Park accommodates six relatively discrete cow elk subherds. Bulls appear to disperse outside CSP more frequently than cows.