Abstracts

Presented by Brendan Shirkey - Email: brendan@winous.org

Autumn waterfowl habitat management often focuses on providing high energy food resources to attract and concentrate waterfowl for harvest. Similarly, many waterfowl conservation plans assume food resources are the primary, controllable limiting factor influencing waterfowl distribution during migration, however hunting-related disturbance also likely influences waterfowl distribution in autumn. We investigated factors influencing mallard (Anas platyrhynchos) movements in an intensively hunted and food-rich landscape. We used locations from female mallards equipped with GPS back-pack transmitters to 1) determine the probability of mallards switching habitat patch types based on seasonal and daily patterns of hunting disturbance and 2) determine the distances mallards moved between habitat patch types that offer refuge and those that offer food resources as evidence for or against food resource depletion during the hunting season. We found mallards switched habitat patch types to exploit food-rich but intensively hunted habitat patches nocturnally and that habitat patch switching during time periods subject to disturbance increased significantly from the early segment to the late segment of hunting season. We also found distances mallards moved between refuge habitat patches and food-rich habitat patches did not change over the duration of the study period. Our findings support that hunting disturbance is a key variable influencing autumn movements and distribution of mallards, and that mallards in a food-rich and intensively hunted landscape employ nocturnal foraging as a strategy to survive autumn migration. Continued investigation is needed to understand waterfowl movements and nocturnal foraging strategies in landscapes that may be less-heavily disturbed and/or provide significantly fewer food resources. Nocturnal foraging behavior has potentially significant and negative consequences for waterfowl managers tasked with providing quality waterfowl hunting opportunities as ducks that only forage nocturnally are largely unavailable to hunters.