Survival of postfledging mallards in northcentral Minnesota

Effective, economical management of waterfowl populations requires an under standing of age-, sex-, and cause-specific forces of mortality. We used rad iotelemetry to estimate survival rates of immature mallards (Anas platyrhyn chos) from fledging to autumn migration in northcentral Minnesota. We monit ored 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 perio d, 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 increa sing recruitment. Management strategies that increased nest success, increa sed brood survival, or decreased hunting mortality would more likely have p roduced meaningful gains in recruitment and are worthy subject's for contin uing study. In northcentral Minnesota, changes in waterfowl habitats, preda tor populations, and hunting pressure have probably not changed the relativ e importance of hunting and nonhunting mortality to fledged juvenile mallar ds since our data were collected.