Arctic Skua – 2007 migration

Stercorcarius parasiticus – SGIWEN Y GOGLEDD – Passage migrant.

The number of birds involved each autumn varied, extremes being 67 in 1993 and 355 in 1985. Differing breeding success no doubt played a part in this variability but changing weather systems seem to have been the main factor.

Autumn totals at Strumble Head, 1980 – 2007.

 Passage has been recorded from July to December, at Strumble Head between 1980 and 2006, a total of 24 being seen in July, 32 in November and 5 in December. Totals for the months August to October, expressed in six day periods were:

Light to moderate winds with a westerly component prevailed in most autumns. It was thought that some of the Arctic Skuas travelling southwards through the Irish Sea were drifted eastwards into Cardigan Bay by these westerly winds. When the skuas encountered the north Pembrokeshire coast they followed it in a westerly direction, so as to gain sea room for their continued southward migration. When south–westerly gales occurred larger numbers appeared in Cardigan Bay, presumed to have been blown there from the sea area south of the Irish Sea. When the wind veered to between west and north before moderating, these birds were able to make their way back out to sea, many of them passing close in to Strumble Head. It was such a weather system that resulted in the largest day total recorded when 103 passed on the 3rd September 1983.

Light to moderate north–east winds predominated in the autumn of 1993 and few Arctic Skuas were seen, most of those that did pass were during short interludes of westerly winds. Strong winds from due east dominated the autumn of 2003 when a total of 203 Arctic Skuas was logged passing. Such winds could be expected to drift southward travelling birds away from Cardigan Bay, so it seems likely that those seen at Strumble Head had arrived by flying overland from the North Sea assisted by the following wind.

Observational evidence indicates that Arctic Skuas are diffusely spread once they have cleared the north coast of the county. Daily observations from The Smalls throughout the autumns of 1983 and 1984 recorded far fewer birds than passed Strumble Head on the same dates. Offshore watchers using boats going as far out as the Celtic Deep only occasionally encountered one or two Arctic Skuas, as was the case with shore based watchers on the west and south coasts of the county and on the offshore islands. At Skokholm the mean autumn total from 1953 to 2003 was seven birds.

The Arctic Skua has been sparse in Pembrokeshire waters during spring, with one to three per annum being the norm during the period 1958 to 2003, passing between the 4th April and the 30th June. Four in 1998, six in 1996, eight in 2002 and 10 in 1993 exceeded the norm. Records came from Tenby, Broad Haven (S), St Govan’s Head, West Blockhouse, St Ann’s Head, Skokholm, Skomer, The Smalls, St Bride’s Bay and Strumble Head.

© 2010 G H Rees

Graham Rees. Pembrokeshire County Bird Recorder 1981-2007

More about the Arctic Skua in Pembrokeshire

Arctic Skua – 2007

Stercorcarius parasiticus – SGIWEN Y GOGLEDD – Passage migrant.

The Arctic Skua has a circumpolar Arctic breeding distribution extending southwards to northern Scotland. Migrants seen passing through British waters are en route to and from Atlantic wintering areas, principally south of the equator.

Mathew (1894) noted just one record of an Arctic Skua, shot at Goodwick, but gave no date. Lockley et al (1949) considered it to be occasional off Skokholm and Grassholm, mainly in August and September but sometimes in May or June.

A mean of 10 per annum was recorded in the county between 1953 and 1975, during a period when little seawatching was conducted. The low detection rate being linked to a paucity of watching was emphasised when Saunders (1976) noted 45 passing Strumble Head on the 8th September 1974. Watching at this headland became more frequent from 1978, with regular autumn observations from 1980 onwards. The annual average total of Arctic Skuas recorded in Pembrokeshire between 1980 and 2003 rose to 235, 90% of them being seen at Strumble Head, passage taking place between July and November, the majority between August and October.

Age and or morph was recorded for the bulk of the Arctic Skuas seen at Strumble Head between 1980 and 2006. Adults made up 67% of the total, of which 31% were light–phase, 33% dark–phase and 3% classified as intermediates, the remaining 33% of the total were predominantly juveniles, though some first and second year birds were identified.

© 2010 G H Rees

More about the Arctic Skua in Pembrokeshire

Arctic Skua – 1994

Stercorcarius parasiticus – SGIWEN Y GOGLEDD – Passage migrant. Not recorded in February and March

Mathew (1894) recorded just one Arctic Skua, but Lockley et al. (1949) commented that they were occasionally seen off Skokholm and Grassholm, usually in August and September, sometimes in May and June. This pattern continued to be recorded, but with autumn occurrences proving to be annual. Records never involved more than four birds on any occasion until ten were seen passing Strumble Head on 11 September 1971 and 50 on 8 September 1974. Saunders (1976) concluded that the number recorded was limited by the “meagre amount of observation carried out from our headlands like Strumble and St David’s”. Subsequent regular and frequent watching at Strumble Head has fully confirmed this view (see Table 13).

There is a north to south passage out of the Irish Sea in the autumn, from mid-July to 20 November, up to ten per day being a typical tally for Strumble Head. However, south-west gales can bring larger numbers to Cardigan Bay. These birds fly out past Strumble Head when the wind veers round north of west, and 30-70 in a day can be seen in such conditions, with 103 passing on 3 September 1983. Like the Pomarine Skua the majority pass out to sea once clear of the Bishops but small numbers, up to six per occasion, occur along the west coast between Skokholm and Grassholm with up to ten in a day further out at the Smalls. A few wanderers turn in to explore the south coast and have even been known to enter the Cleddau Estuary.

Spring passage is small in volume, when one or two can be detected off any of the coasts between 9 April and June or early July, the late birds possibly being non-breeders.

One was seen at Strumble Head on 15 January 1984 and on 20 December 1991.

Donovan J.W. & Rees G.H, 1994, Birds of Pembrokeshire

SAUNDERS, D.R. 1976. A brief guide to the birds of Pembrokeshire. Five Arches Press.

More about the Arctic Skua in Pembrokeshire

Arctic Skua – 1894

RICHARDSON’S SKUA, Stercorarius crepidalus

This is a smaller species, to be at once recognised in the adult, by the two long and pointed central tail feathers. It is more scarce on our south-western coasts than the Pomatorhine Skua, but a season rarely passes without one or two being noticed. Sir Hugh Owen has shot an immature bird at Goodwick. There are two well-marked varieties of this species, one with a white breast and underparts, the other black all over, and in the black birds the blackness differs in its intensity, in some being of a rusty colour, in others of a deep coal black. The two varieties freely interbreed, the result being birds of a mottled plumage We have seen examples pied black and white, the patches of the two opposite colours being symmetrically placed, and giving to the birds a very peculiar appearance

Mathew M.A. 1894, Birds of Pembrokeshire and its Islands

More about the Arctic Skua in Pembrokeshire

Arctic Skua

Stercorcarius parasiticus – SGIWEN Y GOGLEDD – Passage migrant.

Arctic Skua – 2007 migration

Stercorcarius parasiticus – SGIWEN Y GOGLEDD – Passage migrant. The number of birds involved each autumn varied, extremes being 67 in 1993 and 355 in 1985. Differing breeding success no doubt played a part in this variability but changing weather systems seem to have been the main factor. Autumn totals at Strumble Head, 1980 – […]

Arctic Skua – 2007

Stercorcarius parasiticus – SGIWEN Y GOGLEDD – Passage migrant. The Arctic Skua has a circumpolar Arctic breeding distribution extending southwards to northern Scotland. Migrants seen passing through British waters are en route to and from Atlantic wintering areas, principally south of the equator. Mathew (1894) noted just one record of an Arctic Skua, shot at […]

Arctic Skua – 1994

Stercorcarius parasiticus – SGIWEN Y GOGLEDD – Passage migrant. Not recorded in February and March Mathew (1894) recorded just one Arctic Skua, but Lockley et al. (1949) commented that they were occasionally seen off Skokholm and Grassholm, usually in August and September, sometimes in May and June. This pattern continued to be recorded, but with autumn occurrences […]

Arctic Skua – 1949

Species account from the Birds of Pembrokeshire, 1949, by Lockley, Ingram and Salmon.

Arctic Skua – 1894

Species account from the 1894 Birds of Pembrokeshire and its Islands by the Rev. Murray Mathew