Great Skua - occurrence

Stercorarius skua

With an increased number of observers taking an interest in the birds occurring in Pembrokeshire’s offshore waters from 1980 onwards, the number of Great Skuas recorded rose to a level far greater than was expected from the previous sightings , with a mean of 196 per annum between 1980 and 2006. During this period the lowest annual total was 86 in 1993 and the highest 569 in 1983. The bulk of the birds were recorded on autumn passage, between July and November, though probably some of the 71 recorded in December over the years, might also have been migrating. Most were recorded along the north coast of the county, principally at Strumble Head.

AUTUMN TOTALS STRUMBLE HEAD.

Mean pattern of occurrence Strumble Head, 1980 – 2006, birds per six day periods.

The most recorded in a day was 198 on the 3rd September 1983.

It was discovered that the concentrations along the north coast dissipated once the birds had regained sea room when clear of The Bishops, in the same way as Arctic Skuas but less quickly. This is based on observations from boats and from sightings made from The Smalls when the lighthouse was manned by a birdwatcher throughout the autumns of 1983 and 1984. For instance when the maximum of 10 were seen from The Smalls on the 17th October 1983, 49 passed Strumble Head and when more typically three were recorded at The Smalls on the 20th October 1984, 66 were logged at Strumble Head. Numbers passing the offshore islands have also been low, normally between one and four birds on some autumn days, with seven off Skokholm on the 2nd September 1985 and seven off Ramsey on the 8th September 1996 the highest counts. Single birds have also been seen in St Bride’s Bay and off the south coast. However individual Great Skuas have shown a greater tendency to linger for a while than have the smaller skuas. Up to 10 have been encountered in a day in the Celtic Deep and 14 attended a mixed feeding flock of seabirds at Broad sound on the 28th September 1978.

Great Skuas have been recorded around the coast of Pembrokeshire on 19 occasions in January and 20 occasions in February, so evidently in some years they winter nearby. Compared with autumn, spring passage has been slight, with cumulative totals of eight recorded in March, 24 in April, 13 in May and 20 in June, having been detected in about equal number off the west coast and north coast but less frequently from the south coast.

Graham Rees.

(Covers records up to and including 2006).