Interannual linkages between oceanographic condition, seabird behaviour and chick growth from a decadal biologging study

Understanding the causes and consequences of foraging behaviour has been a longstanding research interest in the study of animal behaviour. Long-lived seabirds adapt their foraging behaviour in response to seasonal changes in marine environments, particularly to food availability, and the trade-off between current and future reproduction. This postulates the links and direction of causality between environments, foraging behaviour and chick growth; however, these relationships remain unclear, especially on a decadal scale. Here, we focused on streaked shearwaters, Calonectris leucomelas, breeding in the Sea of Japan, as they are an ideal species for examining seabird behavioural and reproductive responses to marine environmental changes. Individuals of this species have two alternative choices for foraging trips, selecting either the northern part of the Sea of Japan or the northwest Pacific Ocean, which have different oceanographic features. From 2011 to 2021, we recorded foraging trips of chick -rearing streaked shearwaters tagged with GPS loggers, and weighed chicks to obtain yearly chick growth rates. Path analyses were conducted to examine the relationships between the sea surface temperature, foraging behaviour of chick -rearing adults and chick growth rate. The results revealed that a larger variability in the surface temperature of the Pacific Ocean and higher demand from chicks attracted the adults towards the Pacific Ocean, suggesting that the foraging area and marine predator distribution are determined by the interplay of food availability and offspring condition. These findings illustrate the importance of using long-term foraging behaviour data sets to better understand the relationships between environmental conditions, foraging behaviour and chick growth. (c) 2023 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.