Avian predator prey dynamics in Kenai Fjords National Park: Integrating seabird and raptor studies

Phillips, Laura; Weiss, Elisa

In 2012, we initiated a study to better understand the food-web dynamics that determine upper trophic levels and bioaccumulation of contaminants in the marine environment. In combination with ongoing monitoring surveys for peregrine falcons, bald eagles and colonial seabirds, we collected biological samples to evaluate contaminant levels and diet of falcons and eagles nesting in Kenai Fjords National Park (KEFJ) and adjacent Alaska Maritime National Wildlife Refuge lands. In May, using the M/V Serac (53-ft fiberglass live-aboard boat) and helicopter surveys, we located peregrine falcon and bald eagle nest sites to determine territory status (occupancy.) We accessed nest areas of raptors from the ground to collect egg and feather samples for contaminant analyses and prey remains to assess diet. We revisited nest sites in July to determine productivity of raptor nests as well as collect additional prey and feather samples. We surveyed 19 falcon nesting territories in the Kenai Fjords study area, ten of which were occupied by adult peregrine falcons. We confirmed the presence of three chicks at the ten occupied nest territories. We surveyed 69 bald eagle nests on transects, 43 of which were occupied by incubating eagles. We collected samples at nine of these nests and 4 additional occupied nests located off transect. Eight of 13 occupied eagle nests produced at least one young. We collected two bald eagle and four peregrine falcon eggs from nests for a full suite of contaminants analyses. We collected shed feathers from 13 bald eagle and four peregrine falcon nest territories for mercury and genetic analyses. We collected 226 and 34 individual prey items at bald eagle and peregrine falcon nest sites respectively and selected feather samples from 35 of these for mercury content. Initial results suggest that fork-tailed storm petrels and common murres may be important prey for peregrine falcons and bald eagles respectively. Examining the predator-prey dynamics and contaminant burdens of these species will allow us to better understand changes observed in long-term monitoring programs and develop appropriate conservation strategies for KEFJ.

Avian predator prey dynamics in Kenai Fjords National Park: Integrating seabird and raptor studies

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