Preliminary analysis of the foraging strategy of seabirds on the basis of their behavior and physiological cost

Streaked shearwaters (Calonectris leucomelas) are pelagic seabirds that breed on isolated islands in East Asia. Sometimes, they fly long distances to search and forage for food over several hundred kilometers. During the chick-rearing period, efficient foraging is one of the most important tasks for parents because they have to obtain food not only for themselves but also for their chicks. To understand their foraging strategy of streaked shearwaters, their behavior and physiological cost should be quantified. In 2018, we attached GPS and acceleration loggers on breeding shearwaters (15 males and 11 females, including eight pairs) and collected blood samples from them at the deployment and recovery of the loggers. We confirmed that blood drawing from Streaked shearwaters did not have significant adverse effect on their foraging behaviors. We found oxidative and anti-oxidative markers via blood can be useful for assessing the physiological cost of their foraging behaviors. Our finding suggests that females were suffered from heavier stress than males, because females often conducted short trips and increased oxidative stress. To reveal how they perform foraging with minimal cost, we are going to analyze the relationship between foraging behavior and the associated physiological cost in detail.