British Arctic Skuas suffer drastic decline


A new study has revealed an 81 per cent decrease in Arctic Skua breeding success in Britain, caused largely by a reduction in food availablility during the nesting period, leading to fears that the species could be lost as a breeding bird here. Warming sea temperatures have depleted crucial sandeel stocks, with Arctic Skua breeding success falling from an average of 0.9 chicks per pair in the early 1990s, to 0.3 chicks per pair by the 2010s.

The study, overseen by the RSPB's Centre for Conservation Science and recently published in the Journal of Animal Ecology, examined data from 33 Arctic Skua colonies between 1992 and 2015. These colonies hold roughly a third of the UK’s breeding population of Arctic Skuas, all of which are found in Scotland. In 1992, the 33 colonies held 1,061 breeding pairs; by 2015 this had reduced to just 200. If such declines have been mirrored at the other Arctic Skua breeding colonies, it could mean as few as 550 pairs are left in Scotland. 

There could be as few as 550 pairs of Arctic Skua left in Scotland (Michael Southcott).

Dr Allan Perkins, Senior Conservation Scientist at RSPB Scotland and the study’s lead author, said: "We've known for many years that Arctic Skua numbers have been going down in Scotland, but this study reveals just how bad the declines have been at some of their most important breeding sites. Lack of food has been the biggest pressure for these birds, and shows just how vulnerable our seabirds and marine life are; as sandeel numbers have declined around these key north-east areas in Scotland the whole food chain is impacted. If these sharp declines continue, it's possible that Arctic Skuas will be lost as a breeding species in Scotland."

Scotland lies at the southern edge of Arctic Skua's global breeding range, and the loss of it as a breeding species here would represent a significant contraction in their global range. Local populations and breeding successes of four other seabirds from which Arctic Skuas often kleptoparasite – Kittiwakes, Guillemots, Puffins and Arctic Terns – were included as indicators of the food availability in these places. The size of the Arctic Tern, Kittiwake and Puffin colonies studied all reduced by around 90 per cent each, and Guillemots by 42 per cent. At some colonies predation by Great Skuas added to the pressures faced by Arctic Skuas.

Peadar O'Connell, RSPB Scotland's Marine Policy Officer said: "This study provides a shocking snapshot of how Scotland's Arctic Skuas are doing, and an indication of how other seabirds are also faring in north east Scotland. To protect Scottish seabirds, now and into the future, we need to ensure Scotland can provide safe places for them to breed, and secure protected areas for them at sea to feed. One positive outcome would be for the Scottish Government to formally classify the 15 currently proposed Special Protection Areas for seabirds, including two sites for Arctic Skuas."

Depleted fish stocks, particularly sandeels, are having a marked effect on Arctic Skuas (Dermot Breen).