Sandwich Tern - Spring

 Sterna sandvicensis

Spring passage has been documented from the earliest recorded on the 8th March through to the 30th June. Records have involved sightings of from one to twenty birds at a time all around the coast, predominantly from the south coast and the west coast including the offshore islands, with far fewer noted along the north coast. Largest counts were of 22 at Caldey, 33 at Penally, 37 at Lydstep, 25 at Frainslake, 25 at the Gann and 21 at Fishguard Harbour. The general movement northwards to breeding colonies along the coasts of the Irish Sea and further up the west coast of the UK, to some extent makes the north Pembrokeshire coast  a lee shore and probably accounts for lesser numbers occurring there compared with the west coast and islands. It is speculative whether those accumulating along the south coast later move to the Irish Sea to continue their migration, or whether some may follow the shoreline of the Bristol Channel to cross overland to the North Sea. 

 Graham Rees

(Covers records up to and including 2007).

Sandwich Tern - status

 Sterna sandvicensis

Passage migrant.

Sandwich Terns breed on the coasts both sides of the Atlantic, the Mediterranean, Black Sea and Caspian Sea. Those from the north-west of Europe winter mainly on the west coast of Africa.

The Sandwich Tern was a rare visitor to Wales up to the early 20th century. It was first recorded in Pembrokeshire when Bertram Lloyd saw four at Newport on the 3rd June 1928. Variously one to eight birds were then recorded in nine years up to the end of the 1970’s and from the 1980’s onward they were noted frequently each year on both spring and autumn passage.

Graham Rees

(Covers records up to and including 2007).

White-billed Diver - 1999

Gavia adamsii

Vagrant

Breeding range is in high latitudes of the old USSR and parts of North America but distribution is not fully known. In the western Palearctic they winter along the coast of Norway with infrequent occurrences further south.

An adult was seen passing Strumble Head on the 27th September 1999.

Five observers were assembled in “The Lookout” building logging passing birds, mostly seabirds. The observers were:  Cliff Benson, Jack Donovan, Graham Rees, Andrew Sinclair and Ray Wilkinson. All were seated and equipped with binoculars and tripod mounted telescopes. They were sheltered from a force six south west wind, the sky was overcast but visibility was good.

As well as a variety of other birds, four separate Red-throated Divers had passed close inshore when Ray “called” another diver approaching, following the same line of flight. This one was larger with a slower wing beat than the Red-throated’s and when it came level with the observation point exhibited a large slightly yellow white bill which appeared curved upwards. All other visible features were noted and some sketches made, enabling a positive identification as a White – billed Diver and the assessment that it was an adult in transition between summer and winter plumage.

The record was duly accepted by the BBRC and to date remains the sole recorded occurrence for Pembrokeshire and the second for Wales.

Graham Rees

(Covers records up to and including 2008)

Arctic Tern

Sterna paradisaea

Passage migrant.

The Arctic Tern has a continuous circumpolar Arctic and sub Arctic breeding range, the nearest nesting in Wales being at Anglesey and in Ireland in county Wexford. The species winters as far south as the edge of the Antarctic ice and there are ring recoveries of Anglesey birds off South Africa and Australia.

Mathew (1894) stated that the Arctic Tern was “seen commonly on passage in spring and autumn”, but Lockley et al (1949) later noted that they were “no longer seen commonly on passage” and noted just three occurrences, singles at Goodwick on the 13th August 1935 and at Skokholm on the 8th June 1938, with 20 at Dale at the end of April 1947. Donovan and Rees (1994) considered the Arctic Tern to be sparsely recorded in spring when up to eight at a time were seen passing, mainly off the west coast and offshore islands, between the 13th April and the 23rd June, but more numerous in autumn, when up to 30 in a day passed between the 21st July and the 22nd November, principally seen off the north coast.

Any detailed assessment of the Arctic Tern’s status is limited by the fact that only a proportion of Common or Arctic Terns are identified to species, most being logged as “Common or Arctic” , usually expressed as “Commic Tern” . What can be gleaned is that 130 were recorded at Skokholm on the 1st September 1997 and that single birds were recorded away from the coast at Heathfield Gravel Pit on the 23rd September 1999, at Bosherston on the 8-9th May 2000 and at Llawhaden on the 11th May 2000. 

See also the account for Common or Arctic Tern.

Graham Rees.

(Covers records up to and including 2009).

Common or Arctic Tern - Autumn

Sterna hirundo/ paradisaea  

Many more pass through on autumn passage, July to October, than in spring, with occasional accumulations of 100 to 800 birds having been noted off St Ann’s Head, Skokholm, Broad Haven (north) and sea area between Point St John, St David’s Head and the Bishops and Clerks as far out as Bais Bank. However, the majority have been recorded passing along the north coast at Strumble Head. Normally up to 30 per day were seen but periodically larger passages occurred, the largest on record being 190 on the 11th September 1984, 458 on 2nd September 1988, 459 on 27th August 1990, 256 on 11th September 1992, 363 on 4th September 1997, 375 on 1st September 1998, 199 on 17th August 2002, 726 on 31st August 2005 (an additional 151 Common Terns identified as well) and 501 on 8th September 2009.

These large movements have occurred with moderate to strong south or south-east winds, usually accompanied by poor visibility due to rain or drizzle. The terns have arrived on a north-west to south-east track, suggesting they had come from the Wicklow coastal area. The exception was on the 27/8/90 when they arrived from a north-easterly direction, presumably caused by a previous accumulation in Cardigan Bay moving on en masse, there being a moderate south-west wind and good visibility at the time.

Many more Common than Arctic Terns are identified in the county, so probably make up the majority of reported “Commics”.

Graham Rees.

(Covers records up to and including 2009).

Common or Arctic Tern - status

Sterna hirundo/ paradisaea

Passage migrant.

It is not always possible to separate Common from Arctic Terns in the field unless they are close and seen well. However, most observers still wish to record what they see and log these birds as either “Common or Arctic”, usually expressed as “Commic Terns”. The following is a review of such records.

 There has been a marked difference in the nature of spring and autumn passages. There are many breeding colonies of both species to the north and west of Pembrokeshire along the coastlines of both western Britain and eastern Ireland, which are probably the origin of most passing the county. Whereas there has usually been a strong passage of birds migrating southwards from these colonies in the post breeding season, comparatively few have been seen passing northwards on their way to the breeding grounds. Although there are juveniles as well as adults swelling the population in the autumn, this alone does not fully explain the discrepancy in the volume seen. It seems more likely that having spent a pelagic winter season most spring birds pass Pembrokeshire out of sight of land, which would explain why the majority that are detected are to seaward of the islands beyond the west coast and increasing numbers are seen from land further up the narrowing Irish Sea. It is interesting to note in this context that in the spring of 1984, when direct comparison was possible, twice as many were seen passing The Smalls compared to Skokholm. As with other species of migrant birds, spring passage is performed with a sense of urgency to reach the breeding grounds at an optimal time, so is a rapid event. By comparison autumn migrants do not need to travel to their wintering areas according to such a strict schedule, being able to pause and accumulate at rich feeding sources en route.

Common Tern

Sterna hirundo

Passage migrant; former breeder.

The Common Tern breeds across the northern hemisphere from the sub Arctic to the topics, nesting at the coast and by inland water bodies. The European population winters on the west and southern African seaboard. 

Terns breeding on Caldey Island in 1662 were “almost certainly Common Terns” according to Sage (1956). A colony of about 20 pairs nesting on Skokholm Stack was recorded by Mathew (1894) which Lockley et al (1949) believed ceased breeding in 1916. There have been no breeding records in Pembrokeshire since.

Mathew (1894) stated that the Common Tern was “seen commonly on passage in spring and autumn”, but Lockley et al (1949) later noted that they were “no longer seen commonly on passage” and were chiefly seen in September and October. Donovan and Rees (1994) regarded the Common Tern as being sparse in the spring, between the 12th April and the 12th June, with up to 12 a day seen passing northwards off the west coast and associated islands but that they were more numerous in the autumn, between the 21st July and the 28th October, principally seen off the north coast, with the largest day count of 182 off Strumble Head on the 26th August 1990.

Any detailed assessment of the Common Tern’s status is limited by the fact that only a proportion of Common or Arctic Terns are identified to species, most being logged as “Common or Arctic” , usually expressed as “Commic Tern” . What can be gleaned is that the Common Tern has now been recorded in the county as early as the 30th March and as late as the 7th November. It has also been recorded occasionally within the Teifi, Nevern and Cleddau Estuaries, in the latter case as far upstream as Hook. One was seen flying overland at Letterston on the 10th September 1983.

See also the account for Common or Arctic Tern.

Graham Rees. (Covers records up to and including 2009).

Eider - ages

Somateria mollissima

Most observers reporting during the years 1981 to 2006 noted the age of birds seen. 61% were classified as female, 15% as immature males and 24% as adult males. Adult males were rarely seen during the winter months but were more frequently seen among passing groups. Illustrating this point, of 74 adult males recorded during the period, 62 of them migrated past Strumble Head.

Graham Rees.

(Covers records up to and including 2008).

References

MATHEW. M. 1894. The birds of Pembrokeshire and its islands, R. H. Porter.

Eider - breeding

Somateria mollissima

Breeding was suspected at Caldey in 1981 and a flightless group in the St Govan’s Head/Barafundle   area in July 1983 was thought to be a female with a brood of large young.

Eider - passage

Somateria mollissima

Eiders have also been recorded in transit in every month of the year, either flying past prominent headlands like Dinas Head and Strumble Head (1 to 19 at a time), past the islands of Ramsey, Grassholm, Skomer and Skokholm (1 to 15 at a time), or settled temporarily on the sea.

 The latter category has included 30 at the Green Bridge of Wales on 26th April 1984, 38 in Caldey Roads on 25th March 1998, 17 off Solva on 17th April 2001 and 40 off Porthgain on 29th December 2003.

The origin and destination of these birds is unknown but Pembrokeshire lies between the main Eider concentrations in Wales at Aberdysynni, Merrionydd, mean of 72 in 12 recent years, and the Bury Inlet, West Glamorgan, mean of 97 in the same period, so could conceivably involve interchange between these populations.

Eider - status

Somateria mollissima

Winter visitor and passage migrant.

The Eider has a circumpolar Arctic and sub Arctic breeding distribution, extending southwards to northern England and Northern Ireland. They are sedentary and dispersive.

The Eider was first put on record for Pembrokeshire by Mathew (1894) noting an immature male at Dale on the 18th January 1891. He also mentioned that Eiders had been shot at Stackpole and Pembroke but gave no other details. Next noted in 1952, Eiders have been recorded in most years since.

Black-browed Albatross

Diomedea melanophris

Vagrant.

Breeds around the southern oceans, is migratory and dispersive. Classified as accidental to Britain single Black-browed Albatrosses have several times spent prolonged periods at Gannetries.

Two recorded occurrences in Pembrokeshire have been accepted by the BBRC. The first was an adult seen from Skokholm by G.Thompson on the 19th August 1990. The second was also an adult, seen from the Rosslare to Fishguard ferry, when about four miles west of Strumble Head on the 17th September 1990. Both sightings probably refer to the same bird, as might an adult at Strumble Head seen on the 12th September 1990 which was not sufficiently well documented to be fully accepted by BBRC.

The following records are noted here in case they are “discovered” by future researchers: a sub – adult seen from Skomer on the 30th August 1989 was not accepted by BBRC and a white headed, black backed albatross floating past Strumble Head, near Gannets doing the same thing, on the 4th October 1995 was just too distant to be specifically identified by the assembled seawatchers of the day.

Graham Rees

(Covers records up to and including 2006)