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 p rotect or. improve the status of these populations. Age- and sex-speci fic population parameter estimates provide the most useful information for this purpose. Numerous studies have provided information about su rvival rates in mallards (Anas platyrhynchos), but little is known abo ut age-related differences in female survival during the breeding peri od. We examined band-recovery data for female mallards banded in south ern portions of Alberta, Saskatchewan, and Manitoba during spring and summer 1981-85. We used band-recovery models to test the hypothesis th at yearling females would exhibit higher survival compared with that o f older females during spring-summer. There was evidence (P = 0.08) th at spring-summer survival rates of yearling females (0.728) were highe r than that of older females (0.574). These findings support the hypot hesis that age-specific differences in nesting behavior (e.g., later n est initiation and fewer nesting attempts by yearlings) influence loss es to predators and are responsible for the difference in spring-summe r survival. Management treatments that increase nest success, and cons equently reduce the need for prolonged nesting, will increase mallard survival during spring-summer.