Survival and cause-specific mortality of elk Cervus canadensis calves in a predator rich environment

Quantification of basic demographic parameters such as survival rates and cause-specific mortality is important for effective species management. We conducted a 4-year study (during May 2005-June 2009) of elk Cervus canadensis calf survival and cause-specific mortality in Pennsylvania, USA. We captured and radio-collared 93 elk calves <= 7 days old and monitored them weekly to detect mortality and cause of death. Of the 93 radio-collared elk calves, 15(16%) died during our study. Despite high black bear Ursus americanus and coyote Canis latrans densities, none of the mortalities were the result of predation. Causes of death included poaching (N = 3), legal harvest (N = 2), road kill (N = 2), pneumonia (N = 1) and rumen acidosis (N = 1). We were unable to determine the cause of mortality for six of the elk calves; however, predation was eliminated as a possible source of mortality in all unknown cases. Survival probabilities were similar between sexes and among years. Summer survival (birth-31 October) was 0.92 (SE = 0.03, N = 93) and winter survival (1 November - 1 April) was 0.90 (SE = 0.04, N = 79). Annual estimated elk calf survival was 0.82 (SE = 0.04, N = 93). Our findings suggest that Pennsylvania elk calves have a > 80% chance of survival to one-year of age, despite high densities of predators known to influence elk calf survival elsewhere. The high calf survival rates that we observed indicate the availability of high quality habitat leading to excellent physical condition of elk.