Red-legged kittiwake foraging ecology


Early breeding season responses of red-legged kittiwakes to changes of prey availability and linkages to the non-breeding stage    

 Project Objectives

1) Determine life history responses (e.g. onset of egg laying, egg size, and hatching and breeding success) of red-legged kittiwakes in relation to foraging ecology (e.g. habitat use, and diet), and adult condition (nutritional stress, body condition, and mercury loads) during the pre-lay and incubation phases of breeding under poor (high pink salmon) and good prey conditions (low pink salmon).

2) Determine linkages (carry-over effects) between breeding success and the winter season in terms of migration timing, routes, habitat use and ultimately survival.

        For seabirds to function as indicators of ecosystem health it is critical to understand how prey availability might mediate life history and demographic responses to environmental variability. These responses have been linked to foraging patterns during the chick-rearing period, however, how prey availability at early reproductive stages affects decisions during current and future breeding attempts is less clear. This study investigates the foraging ecology and breeding performance of the vulnerable red-legged kittiwake (Rissa breviosious, IUCN) over two breeding (summer) and non-breeding (winter) periods at St. George Island in the southeastern Bering Sea. The main goals of this study are to relate the foraging behavior of individual birds to pre-lay and incubation breeding parameters (onset of egg laying, egg size, hatching success) and to assess carry-over effects of breeding outcomes and winter migrations to adult survival. To accomplish these goals we will employ biologging techniques to determine spatial distributions and foraging effort of kittiwakes, in combination with biochemical techniques, such as bulk stable isotope analysis to assess diets, and hormone, telomere, and contaminant assays to determine adult quality and condition. Nests of tracked birds will be monitored to determine return rates and success at each reproductive stage. Pink salmon (Oncorhynchus gorbuscha) are a dietary competitor of red-legged kittiwakes and will serve to provide the context for kittiwake response to prey availability. In the Bering Sea, pink salmon cohorts follow a predictable alternation between large and small cohorts, creating a natural experiment that can be used to understand foraging dynamics under relatively good (low salmon) and poor conditions (high salmon). Our longitudinal approach across seasons would allow for direct linkages between individual foraging behavior and population dynamics of a vulnerable migratory seabird and its changing environment in the Bering Sea.

The Team

Rosana Parades (OSU)
Rachael Orben (OSU)
Sasha Kitaysky (UAF)
Scott Shaffer (SJSU / UCSC)
Abram Fleishman (SJSU)

Funded by the North Pacific Research Board (