Plastic Foraging Behavior and the Implications for Increased Fishery Interactions

Abstract

Offspring provisioning constrains the foraging behavior of breeding seabirds temporally and spatially. In species whose foraging grounds overlap with commercial fisheries, quantifying the provisioning behavior of breeding adults throughout the season can illuminate the nature of interactions with the fisheries and, where seabird bycatch exists, contribute to development of mitigation measures. In 2004-2005, we studied the provisioning behavior of Flesh-footed Shearwaters (Puffinus carneipes) on Lord Howe Island, Australia, using the repeated-weighing technique. Specifically, we determined (1) meal size, feeding frequency, and chick growth rates; (2) attendance behavior of adults; and (3) estimated food consumption at the individual and colony levels. Incubation shift duration averaged 95 +/- 1.6 (SD) days. Foraging-trip duration was bimodal, with both short trips ( 3 days) recorded. Average meal mass was greater during the late chick-rearing period and was not influenced by the time interval between meals. Developing chicks had a food conversion efficiency of 27%, with a total individual food requirement of 2,337 g to fledge successfully. An increase in the interval between provisioning events from the early to the late chick-rearing period was associated with significantly more long foraging trips by parent birds; however, there was no variation in the proportion of study birds that returned each night. Received 2 September 2008, accepted 19 May 2009.