Changes to the British List (13 August 2021)
The British Ornithologists’ Union Records Committee (BOURC) has made the following change to the British List:
The following species have been added to the British List:
South Polar Skua Stercorarius maccormicki
One, second-calendar-year, West Bexington, Dorset,
27 January to 4 February 1996.
Photo (right) © P & C Leigh
This Antarctic species is a predicted vagrant to British waters as dataloggers have demonstrated that significant numbers migrate annually to the northern hemisphere (Marine Ecology Progress Series 435: 263-267), with regular sight records elsewhere in the eastern and western North Atlantic. However, despite several claims, the status of this species, and its austral sister species Brown Skua S. antarcticus, as a vagrant to Britain has been problematic, as they are difficult to separate, having very similar plumage to each other and Great Skua S. skua, and as mitochondrial DNA does not distinguish between the taxa (IBIS 149: 619-621). This individual was assessed solely on a series of photographs taken throughout its extended stay, often sitting on a beach. These images allowed the bird to be aged as second-calendar-year on a basis of moult, plumage state and bare part colouration, crucial for its identification.
It should be placed after Black Tern Chlidonias niger on the British List.
South Polar Skua is widespread in the Southern Oceans where it nests on the Antarctic continent and disperses large distances during the non-breeding season, as far as the northern oceans.
This change will be published as part of the BOURC’s 53rd report due to be published in IBIS in October 2021.
Upon publication of this change, the British List stands at 627 species (Category A = 609; Category B = 8; Category C = 10)..