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A WORLD OF DECISIONS: HOW CHOICES THROUGHOUT THE ANNUAL CYCLE AFFECT SURVIVAL, CONDITION, AND PERFORMANCE OF A MIGRATORY SHOREBIRD

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Abstract

Migratory birds face a variety of threats and constraints throughout the annual cycle, and events that occur in one season can impact individuals not only within that period, but in subsequent seasons as well. I investigated the consequences of decisions about habitat use and species interactions across the full annual cycle on the survival, condition, and performance of Hudsonian Godwits (Limosa haemastica) in Beluga River, Alaska and Chiloé Island, Chile. On the breeding grounds, I examined how the benefits of a protective nesting association between godwits and the loud and aggressive Mew Gulls (Larus canus) varied across time and space. Hudsonian Godwits actively chose to nest within gull colonies, but the advantages were context-dependent. Although godwits experienced higher nest survival within colonies – presumably because gulls dissuaded nest predators from using the area – godwit chicks were more likely to be depredated within colonies. Godwits nesting within colonies were larger (females only) and less attentive (males attended the nest less and gave fewer alarm calls). Nest survival was best explained by individual condition improving with female size within colonies and male size outside of colonies. Turning to the non-breeding grounds in southern Chile, I assessed the degree to which patch quality, as indicated by density and condition of godwits, was affected by environmental attributes and disturbance from predators and/or human activities. Patch quality was primarily influenced by availability of foraging habitat, foraging success rates, and the responses of godwits to disturbance (i.e., vigilance and agitation). Lastly, I examined cross-seasonal interactions on individual survival and performance. Godwits had high survival throughout the annual cycle, with the lowest survival estimates during the breeding season and southbound migration. I also found evidence of carry-over, or reversible state, effects on future reproductive performance, with individuals in better condition or using higher quality patches on non-breeding grounds achieving higher reproductive success the following spring. Understanding the interactions among stages of the annual cycle, the relative influence of non-breeding and breeding season factors, and the consequences of individual decisions on survival, condition, and performance will help inform conservation for this rapidly declining species.

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2018-08-30

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Behavioral sciences; annual cycle; Hudsonian Godwit; interspecific interactions; Limosa haemastica; reversible state effects; shorebird; Ecology; Wildlife conservation

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Committee Chair

Rodewald, Amanda Dumin

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Senner, Nathan Robert
Fitzpatrick, John Weaver
Webster, Michael Stilson, Jr

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Natural Resources

Degree Name

Ph. D., Natural Resources

Degree Level

Doctor of Philosophy

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dissertation or thesis

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