NSF Award
9908624
R. Veit OPP99-08624<br/>D. Grunbaum OPP99-08623<br/>Antarctic seabirds such as Black-browed Albatrosses acquire essential resources on foraging trips that span many days and thousands of kilometers. The success of these foraging excursions is primarily limited by sensory limitations that restrict detection of prey to relatively short ranges. To overcome this sensory limitation, abatrosses use a combination of memory of previous foraging locations and short-term responses to the prey distributions they are presently encountering. We have already quantitatively characterized two of these short-term behaviors, area-restricted search and local enhancement, in Black-browed Albatrosses. We hypothesize that these behaviors are fundamental determinants of long-term, large-scale patterns in the albatross' spatial foraging dynamics. If we are correct, then short-term, ship-board observations coupled with detailed spatially explicit models of foraging behaviors will have important predictive power for where albatrosses forage, how successful they are, and how that success is affected by short- and long-term changes in prey distribution. We propose to test our hypothesis initially by constructing a spatially explicit model of foraging behavior, based on extensive reanalysis of existing behavioral data from our own cruises and from the literature. The model will take advantage of newly developed mathematical techniques to relate these complex individual-level behaviors to the spatio-temporal distributions of seabird populations that result from them. The primary goals of this work are to create and disseminate a flexible modeling structure, to use that structure to establish whether the behaviors we have observed are quantitatively important determinants of where seabirds forage, and to identify the most essential behavioral and environmental data to collect on future cruises. If the model supports our hypothesis, this work will motivate future studies in which we explicitly test our predictions with satellite tracking, ship-board and colony-based observations. If the hypothesis is not supported, our work will focus attention on alternative components of behavior and provide a theoretical structure to investigate them. In either case, this theoretical analysis is an essential first step in attaining an empirically-based, quantitative understanding of spatial foraging dynamics in Antarctic seabirds.
