Summary:
The population dynamics of kittiwakes and other seabirds in Prince William Sound are usually in a state of flux. At any given time, some colonies are growing and some are declining. Although there is strong evidence that variation in food supply underlies much of the fluctuation in colony size, the mechanism by which food supply influences colony dynamics needs to be more clearly defined. Analysis of demographic data indicates that the rate of population change for a given colony is closely related to the breeding success of that colony. Breeding success in turn is related to the rate at which food is delivered to chicks and the quality of that food. Using detailed data on the movement patterns and foraging behavior of radio-tagged kittiwakes coupled with extensive concurrent aerial surveys of fish schools, we have constructed a computer model designed to mimic the behavior of a foraging kittiwake. This model can be used to simulate the response of a foraging kittiwake to various patterns of food distribution and abundance. These simulated foraging behaviors can then be used to predict the distance that adults must travel in order to forage, and the rate and nature of food deliveries to the chicks. Since chick survivorship is known to be strongly influenced by these factors, we believe that it will be possible to make predictions about the performance of individual colonies based on hypothetical fluctuations in the distribution and abundance of the forage fish.


Principal Investigators:
R. Glenn Ford, R.G. Ford Consulting Company, Portland, OR
David G. Ainley, H.T. Harvey Associates, Alviso, CA
David C. Schneider, Memorial University of Newfoundland, St. Johns, NFLD