SURVIVAL RATES OF FEMALE MALLARDS WINTERING IN THE PLAYA LAKES REGION

Effective management and modelling of the Playa Lakes Region (PLR) mallard (Anas platyrhynchos) population requires season and cause specific survival estimates. Habitat protection and management strategies will benefit from survival data as well. Thus, we monitored 153 radio-marked female mallards during 3 winters 1986-87 to 1988-89, to examine factors affecting survival in the PLR. Mean survival rate during the 100-day period 21 November to 1 March was 0.777 +/- 0.04 (SE). We did not detect any age or annual differences in survival. Precipitation and habitat availability varied among years. Survival rates (S) were higher (P < 0.10) for individuals in good body condition (s = 0.888 +/- 0.07) than those in poor condition (S = 0.661 +/- 0.09). The hunting season mortality rate was 0.018 +/- 0.05. Natural mortality, which included avian predation, during the 100-day study period was 0.210 (+/- 0.07). Crippling mortality could not be determined because of rapid carcass loss. Early season body condition and extended sub-freezing weather appear to impact mallard survival most in the PLR. Habitat management should encompass the entire PLR to include secondary habitats used by mallards during freezing weather.