Year round movements of the Arctic Skua - understanding drivers of change in a declining species

• Main Authors: 3rd World Seabird Conference 2021, Humphreys, Liz
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Underline Science Inc. 2021
• Subjects: Animal Science; Ornithology; Emerging Technologies; Arctic; Arctic skua; Stercorarius parasiticus
• Online Access: https://dx.doi.org/10.48448/qeyp-y980; https://underline.io/lecture/34786-year-round-movements-of-the-arctic-skua---understanding-drivers-of-change-in-a-declining-species

Abstract: The Arctic Skua Stercorarius parasiticus is the most rapidly declining breeding seabirds species in the UK, with losses of around 82% since the mid-1980s being reported. Typically these species obtain the vast majority of their food via kleptoparasitism of other seabirds around their breeding territories, many of which are also showing losses although not to the same extent. They are also long distance migrants, with ringing recoveries from the UK being reported across the whole extent of the Atlantic. To help provide some insight into the mechanisms underlying these dramatic changes, we instigated a tracking programme to look at foraging behaviour during the breeding season as well as the migration routes and wintering location at two colonies in Scotland - Fair Isle and Rousay. Arctic Skuas from Fair Isle, which have tended to have poor hatching success, were travelling up to 200 km away from the colony during incubation. Long foraging ranges are indicative of low food availability and similar routes were also recorded by target host species in recent years. Whereas birds from Rousay, which usually have had higher breeding success, generally travelled shorter distances during the same period. Birds from Rousay which successfully fledged chicks tended to forage up to 70 km to the north-west of the colony in an area with specific oceanographic features and designated as a Marine Protected Area for larvae Sandeel - a key fish species. Unsuccessful birds tended to forage elsewhere. We will discuss why these differences should arise with respect to possible differences in foraging behaviours between individual birds. There was clear variation in bird's choice of wintering areas with individuals from the same colonies ranging from South America, Southern and Western Africa. Therefore conservation measures for birds in the UK might be best focused around their breeding colonies. Authors: Liz Humphreys¹, Sarah Harris², Helen Aiton¹, David Aiton¹, Chris Thaxter², Dawn Balmer², Calladine John¹ ¹British Trust for Ornithology, Scotland, ²British Trust for Ornithology