Nesting Productivity of Black-Legged Kittiwakes and Common Murres at Two Seabird Colonies in Lower Cook Inlet, Alaska

FIELD: Murre Productivity Cameras were deployed on each nesting colony to capture time lapse photography of Common Murre nests. Approximately two cameras were stationed at each nesting location, with a wide angle view covering most of the colony, varying from 10-100 nests in view, depending on location. Cameras were collected at the end of each nesting season (late September) and the photographs were analyzed. We calculated productivity for Common Murres by dividing the number of chicks estimated to be over 15 days old observed by the number of eggs laid.

FIELD: Kittiwake Productivity To calculate Black-legged Kittiwake productivity in 2016-2019 photos were taken of historical population plots (1995-1999) at multiple times throughout the breeding season. We obtained an index of production for kittiwakes based on brief assessments of the proportion of chicks counted late in the season compared to the number of nests counted during middle incubation, as in Piatt (2002). We counted each kittiwake nest that was well developed, with new nesting material and a defined nest cup. We summed the maximum number of chicks observed on each population plot throughout the season and divided that by the sum of the maximum number of well-developed nests counted on each population plot. We included one new plot on Chisik Island in 2018 and 2019 that had adequate visibility for observing chicks.

LAB: Murre Productivity Photographs from the field cameras were manually analyzed for nesting productivity and predation events. Photos from each camera were stitched together into a video file, which was watched by a trained observer. Nests were recorded when an egg was seen, or when a bird remained in incubating posture throughout multiple flush events. The nest was then tracked until the egg was observed to be predated, or disappeared (assumed predation).

LAB: Kittiwake Productivity Photos taken in the field to calculate Black-legged Kittiwake productivity were organized based on population plot and date and zoomed in photos were merged using Photoshop when needed. Photos were then loaded into ArcMap 10.7.1, where point shapefiles were used to count the number of each nest and to detect eggs or chicks throughout the season.

LITERATURE CITED: Piatt, J.F., 2002. Response of seabirds to fluctuations in forage fish density. USGS Final Report to Exxon Valdez Oil Spill Trustee Council and Minerals Management Service. Anchorage, Alaska. 406 pp.