Reproductive success of elk following disturbance by humans during calvingseason

Restricting human activity in elk (Cervus elaphus) calving areas during cal ving season can be controversial because of increasing human uses of elk ha bitat, and little evidence exists to evaluate impacts of these activities o n elk populations. We evaluated effects of human-induced disturbance on rep roductive success of radiocollared adult female elk using a control-treatme nt study in central Colorado. Data were collected during 1 pretreatment yea r and 2 treatment years. Treatment elk were repeatedly approached and displ aced by study personnel throughout a 3-4-week period of peak calving during both treatment years, while control elk did not receive treatment. We obse rved elk on alpine summer ranges in July and August on both areas to estima te the proportion of marked cows maintaining a calf. Calf/cow proportions f or the control area remained stable, but those for the treatment area decli ned each year. Average number of disturbances/elk/year effectively modeled variation in calf/cow proportions, supporting treatment as the cause of dec lining calf/cow proportions. Average decrease in calf/cow proportion in the treatment group was 0.225. Modeling indicated that estimated annual popula tion growth on both study areas was 7% without treatment application given that existing human activities cause some unknown level of calving-season d isturbance. With an average of 10 disturbances/cow above ambient levels, ou r model projected no growth. Our results support maintaining disturbance-fr ee areas for elk during parturitional periods.