Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Biology

Supervisor

Petrie, Scott

2nd Supervisor

Guglielmo, Chris

Co-Supervisor

Abstract

During autumn and winter, mallards (Anas platyrhynchos) maximize fitness through their spatiotemporal distribution to avoid mortality risks while balancing trade-offs to access foods to undergo migration and maintain homeostasis. Thousands of mallards use Lake St. Clair as it is an important, but threatened, migratory staging area in the Great Lakes. My goal was to understand how mallards were selecting resources in the region and potential relationships of selection strategies. My objectives were to estimate resource selection of adult female mallards, in relation to perceived risk of hunting mortality, and determine if selection strategies were related to survival and timing of departure. At Lake St. Clair, I equipped 59 adult female mallards with GPS back-pack transmitters to monitor resource selection and movements from 27 August to 31 January 2014–15 and 2015–16. I used discrete-choice modeling to determine if mallard resource selection strategies were best explained by composition of habitat type (i.e., quality) and ownership type (i.e., presumed level of mortality risk). I observed selection for habitat types managed by the Canadian Wildlife Service, private landowners, and Michigan Department of Natural Resources throughout the monitoring period. I classified these habitat types as low to moderate mortality risk. The area of public water was selected for prior to and after the hunting season and classified as high mortality risk, suggesting that disturbances and mortality risks from hunting could have influenced selection. I used time-to-event analysis to determine how diurnal selection estimates were related to mortality risk and probability of regional departure. As mallards selected public water, mortality risk decreased during the non-hunting season, but increased during the first half of the hunting season. Probability of departure decreased with selection for public water across the second half of the hunting season and post hunting season. Selection for Walpole Island water was related to an increase in mortality risk and departure probability across seasons. As mallards selected for private water, departure probability decreased during the second half of the hunting season, but increased during the post hunting season. My research describes how mallards select resources in a heterogeneous landscape of resources and risks.

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