Date of Award

Spring 5-13-2017

Level of Access Assigned by Author

Open-Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Wildlife Ecology and Wildlife Conservation

Advisor

Cynthia Loftin

Second Committee Member

Shawn McKinney

Third Committee Member

Erik Blomberg

Additional Committee Members

Brian Olsen

Jeffrey Runge

David Irons

Abstract

Seabirds have great potential to serve as marine indicators. However, before we can interpret seabird trends with confidence, we need a better understanding of the role of intrinsic processes, mediating influences, and lifetime experience in modulating relationships between prey availability and seabird population dynamics.

Intrinsic processes, mediating influences, and seabird productivity. I assessed productivity (chicks per breeding attempt) at Black-legged Kittiwake (Rissa tridactyla) colonies in Prince William Sound, AK and managed Common Tern (Sterna hirundo) colonies in the Gulf of Maine. Both systems showed evidence of intrinsic control; factors mediating access to prey were also important.

Mediating influences, individual heterogeneity, and seabird productivity. Productivity integrates events over successive reproductive stages, so events at one stage can modulate the effects of events at other stages. I investigated the effects of individual age and multiple stressors on kittiwake reproduction in Alaska. I found older birds enjoyed greater success across the board, but different external influences drove success at different stages. These results highlight the need to account for both individual heterogeneity and potential interactions among extrinsic processes in interpreting seabird productivity.

Individual heterogeneity and reproductive costs. Reproduction can incur short-term costs in the form of reduced parental survival or breeding activity in the following season. I found evidence of long-term costs in kittiwakes that underwent 0-4 forced nest failures in the early 1990s. Individuals that were forced to fail more were less likely to skip breeding over the following decade, presumably due to associated cost savings. The lack of an observed survival effect suggests that survival is well-buffered in long-lived species, with costs instead borne by parameters less important to lifetime reproductive success.

Intrinsic processes, individual heterogeneity, and seabird survival and recruitment. I investigated the role of colony size in survival, recruitment, and post-recruitment survival of kittiwakes from an Alaskan colony. I found declines in apparent survival associated with increased colony size, likely resulting from increased dispersal of individuals as the colony grew. Recruitment was age-dependent. These results highlight the need to consider intrinsic processes when relating marine bird population dynamics to prey availability and changes in marine ecosystems.

Download

Share