Factors influencing breeding season survival of female mallards in the Great Lakes region

Mallards (Anas platyrhynchos) are one of the most widely studied waterfowl species in North America, yet there are unknown demographic vital rates that are critical to enhancing the management of this waterfowl species. Specifically, information on breeding season survival rates of female mallards in the Great Lakes region is lacking. We estimated breeding season survival for 484 individually radio-marked female mallards across 9 study sites in the Great Lakes region from 2001-2003. We modeled the effects of study site, year, state, female age (after second year [ASY] vs second year [SY]), body condition, and 3 time periods within the breeding season. Additionally, we created utilization distributions (UDs) (i.e., home ranges), estimated core areas for 282 individuals, and quantified land cover types in those core areas to model the effects of those cover types on breeding season survival. Survival ranged from 0.62-0.85 and the mean across all sites was 0.76. Survival was lowest during the peak nesting period, but study site, year, state, age, and body condition had no significant effect on survival. Our top model suggested that breeding season survival decreased as the percent composition of forested cover within the core areas increased (Beta = -1.740, 95% CI Lower = -3.282, Upper = -0.197). Breeding season survival estimates were similar to those estimated elsewhere and we failed to detect a strong relationship between most land cover types within core areas and survival, suggesting that female mallard survival in the Great Lakes region may be affected by land cover factors not assessed as a part of this study or at alternative spatial scales.