Abstract: Seabird-fishery interactions are important to seabird ecology and conservation since some species obtain a significant amount of food from fisheries, but mortality from bycatch is a primary cause of population declines in several species. While the availability of high resolution GPS data for both seabirds and vessels over the past few years has allowed analyses of fine-scale behavioural responses of seabirds near fishing vessels, little information is available on the distance at which seabirds respond to vessels. Indeed, previous studies have focused on the foraging behaviour of individuals within the vicinity of vessels but have not considered the approach phase of birds. Here we provide such an estimate by examining changes in the flight direction of GPS-tracked wandering albatrosses breeding on the Crozet Islands in response to the toothfish fishing fleet operating around the breeding grounds, monitored using GPS vessel monitoring system data. We show that although we detect increases in feeding behaviour only when albatrosses are within 3 km of boats, they display clear changes in flight direction, towards vessels, at distances up to 30 km. This distance is nearly 3 times as large as previous estimates, almost reaching the theoretical maximum visual range of an albatross. We discuss these results in the light of previous estimates, and pinpoint factors likely to affect the attraction distance. We suggest that this simple estimate of attraction distance could be investigated in other seabird-fishery systems, to improve our understanding of the factors affecting seabird interaction behaviour, and thus better predict when overlap will lead to interactions.

Abstract: Late breeding usually occurs during years of poor environmental conditions, but the proximate mechanisms underlying this phenological pattern have been poorly documented. Here, we combined the deployment of GPS devices (from 2008 to 2010) and the monitoring of breeding parameters and baseline corticosterone levels (from 2007 to 2011) during the pre-laying period to investigate the proximate regulation of breeding date in an Arctic population of black-legged kittiwake Rissa tridactyla. The timing of breeding varied considerably during the course of the study and late breeding was associated with reduced clutch size and low breeding success at the individual level. Foraging strategies differed considerably between males and females and among years. All but one of the females tracked using GPS during the pre-laying period foraged inside the fjord, whereas tracked males foraged both inside and outside the fjord, using the deep waters of the Greenland-Svalbard ridge. Trips lasted longer and were to greater distances in 2009, the year of late breeding, compared to 2008 and 2010, highlighting a food scarcity in 2009. Corticosterone levels differed among years, and were the lowest in 2010, the year of earliest breeding. Moreover, kittiwakes exhibiting higher corticosterone levels tended to undertake longer trips when foraging outside the fjord. Breeding decision and laying date were not related to corticosterone levels at the individual level, but were positively influenced by body condition, suggesting that complex proximate mechanisms may affect timing of breeding in kittiwakes.