SPRING-SUMMER SURVIVAL RATES OF YEARLING VERSUS ADULT MALLARD FEMALES

Knowledge of the timing, magnitude, and cause of mortality in wildlife populations is imperative for developing management strategies that protect or. improve the status of these populations. Age- and sex-specific population parameter estimates provide the most useful information for this purpose. Numerous studies have provided information about survival rates in mallards (Anas platyrhynchos), but little is known about age-related differences in female survival during the breeding period. We examined band-recovery data for female mallards banded in southern portions of Alberta, Saskatchewan, and Manitoba during spring and summer 1981-85. We used band-recovery models to test the hypothesis that yearling females would exhibit higher survival compared with that of older females during spring-summer. There was evidence (P = 0.08) that spring-summer survival rates of yearling females (0.728) were higher than that of older females (0.574). These findings support the hypothesis that age-specific differences in nesting behavior (e.g., later nest initiation and fewer nesting attempts by yearlings) influence losses to predators and are responsible for the difference in spring-summer survival. Management treatments that increase nest success, and consequently reduce the need for prolonged nesting, will increase mallard survival during spring-summer.