Antarctic petrels ‘on the ice rocks’: wintering strategy of an Antarctic seabird

Abstract

There is a paucity of information on the foraging ecology, especially individual use of sea-ice features and icebergs, over the non-breeding season in many seabird species. Using geolocators and stable isotopes, we defined the movements, distribution and diet of adult Antarctic petrels Thalassoica antarctica from the largest known breeding colony, the inland Svarthamaren, Antarctica. More specifically, we examined how sea-ice concentration and free-drifting icebergs affect the distribution of Antarctic petrels. After breeding, birds moved north to the marginal ice zone (MIZ) in the Weddell sector of the Southern Ocean, following its northward extension during freeze-up in April, and they wintered there in April–August. There, the birds stayed predominantly out of the water (60–80% of the time) suggesting they use icebergs as platforms to stand on and/or to rest. Feather δ 15 N values encompassed one full trophic level, indicating that birds fed on various proportions of crustaceans and fish/squid, most likely Antarctic krill Euphausia superba and the myctophid fish Electrona antarctica and/or the squid Psychroteuthis glacialis . Birds showed strong affinity for the open waters of the northern boundary of the MIZ, an important iceberg transit area, which offers roosting opportunities and rich prey fields. The strong association of Antarctic petrels with sea-ice cycle and icebergs suggests the species can serve, year-round, as a sentinel of environmental changes for this remote region.

Influence of reproductive output on divorce rates in polar seabirds

“…These five species are seabirds, which breed on land and remain at sea during the internuptial period (Coulson, 2011 ; del Hoyo et al., 1992 ; Delord et al., 2020 ; Frederiksen et al., 2012 , 2016 ; Gaston & Jones, 1998 ; Weimerskirch et al., 2015 ; Weiser & Gilchrist, 2020 ). They are all characterized by high adult survival rates and thus long lifespans (adult survival rate: 0.85 for R. tridactyla , 0.88 for U. lomvia , 0.85 for L. hyperboreus , 0.91 for T. antarctica and 0.91 for S. maccormicki , Anker‐Nilssen et al., 2020 ; Descamps et al., 2016 ; Fluhr et al., 2017 ; S. Descamps, unpublished data).…”

“…Svarthamaren also hosts 100-150 skua breeding pairs nesting in the lower flat parts, relying exclusively on petrel eggs and chicks as their food resource during the breeding season (Busdieker et al, 2020). These five species are seabirds, which breed on land and remain at sea during the internuptial period (Coulson, 2011;del Hoyo et al, 1992;Delord et al, 2020;Frederiksen et al, 2012Frederiksen et al, , 2016Gaston & Jones, 1998;Weimerskirch et al, 2015;Weiser & Gilchrist, 2020). They are all characterized by high adult survival rates and thus long lifespans (adult survival rate: 0.85 for R. tridactyla, 0.88 for U. lomvia, 0.85 for L. hyperboreus, 0.91 for T. antarctica and 0.91 for S. maccormicki, Anker-Nilssen et al, 2020;Descamps et al, 2016;Fluhr et al, 2017;S.…”

Annual variations in the migration routes and survival of pelagic seabirds over mountain ranges

“…Pelagic seabirds have evolved physiological and morphological characteristics that enable them to fly in an energy efficient manner over the oceans. Although there are some exceptions (e.g., Delord et al 2020), most species come ashore only to breed or rest. However, recent tracking technologies have revealed some unexpected overland journeys.…”

Very Low Density and Biodiversity of Seabird and Marine Mammal at-sea Distribution in the Amundsen Sea, 2010

“…Such a phenomenon has been noted previously in 1994 [3]. It may be corresponding to the end of the breeding season, which is also beginning the annual moult and/ or as wintering strategy [21]. The importance of such hotspots has been seen, too, close to the Antarctic Peninsula [22].…”