Estimates of calf survival and factors influencing Roosevelt elk mortality in northwestern California

Survival of juvenile ungulates is known to be highly variable, yet it is fundamental to understanding the dynamics and trends of wildlife populations. Factors influencing calf survival are poorly understood in northwestern California where Roosevelt elk (Cervus canadensis roosevelti) are known to exist. The objectives of this study were 1) to estimate summer and annual survival rates and determine recruitment rates for Roosevelt elk calves in the area, 2) to evaluate differences in calf survival by examining the effects of individual and population level covariates on summer and annual calf survival, 3) to identify factors influencing the timing and cause of calf mortalities, and 4) to establish a baseline of mortality factors influencing elk across all age classes. Over two seasons, this study captured and marked 58 calves and 28 cow elk in Del Norte and Humboldt counties. Calf survival was 0.67 (SE = 0.009) during the first 14 weeks of life (summer) and 0.82 (SE = 0.001) annually. Birth weight, study area, and the linear trend of time were found to be the most important covariates for summer survival, while the variable effect of time was most important for annual survival of calves. Predation was the top cause of death in calves and black bears (Ursus americanus) accounted for 22% of marked calf mortality. Across all age classes, human-caused mortality (roadkill, legal harvest, euthanasia, and poaching) was the most prominent for adults and yearlings. This is the first study to document calf survival and recruitment in northwestern California and provides evidence that calf survival is high but is not uniform across the area. These results will aid managers in setting appropriate harvest quotas for elk across the hunt zone and provides justification to implement targeted management that alleviates conflict