Survival of postfledging mallards in northcentral Minnesota

Effective, economical management of waterfowl populations requires an understanding of age-, sex-, and cause-specific forces of mortality. We used radio telemetry to estimate survival rates of immature mallards (Anas platyrhynchos) from fledging to autumn migration in northcentral Minnesota. We monitored 48 females and 42 males during 1972-74 and observed 31 deaths during 2,984 exposure-days. We attributed 7 deaths to predation and 24 to hunting. Survival rates were 0.86 (SE=0.047) for the postfledging-prehunting period, 0.29 (SE=0.107) from the onset of hunting to migration, and 0.25 (SE=0.094) for both periods combined. Natural mortality of fledged young had a negligible effect on recruitment to migration. Reducing natural mortality of fledged juvenile mallards would not have been a feasible means of increasing recruitment. Management strategies that increased nest success, increased brood survival, or decreased hunting mortality would more likely have produced meaningful gains in recruitment and are worthy subjects for continuing study. In northcentral Minnesota, changes in waterfowl habitats, predator populations, and hunting pressure have probably not changed the relative importance of hunting and nonhunting mortality to fledged juvenile mallards since our data were collected.