Common Tern - 1949

Sterna hirundo hirundo

In Mathew's time there was stil a small colony on Skokholm Stack, and it was also a common migrant in spring and autumn.  It is believed that it ceased to breed Skokholm in 1916.  Now by no means common even on passage, when it is chiefly seen in September and October.

R.M.Lockley, G.C.S.Ingram, H.M.Salmon, 1949, The Birds of Pembrokeshire, The West Wales Field Society

Common and Arctic Tern - 1994

Passage migrant. Not recorded from December to February

It is often difficult to separate Common from Arctic Terns, particularly at a distance, and consequently the majority of records received refer to 'Comic' Terns (Common or Arctic). The following summary is based on such records.

There is a sparse spring passage of birds passing northwards between 2 April and 30 June; Lockley (1961) also includes March but gives no specific dates. This passage is most visible from the offshore islands, when typically only small parties of up to five are seen on scattered dates, but groups of up to 14 have been noted.

They are much more frequent and numerous in the autumn, between July and late October, when they explore inshore waters to a greater extent than in spring. Some birds penetrate into the estuaries with notable gatherings at rich food sources, such as 300 off Skomer in August 1975, over 400 at Broad Haven (north) in September 1974 and 800 off St Ann's Head on 22 September 1979. This kind of incursion apart, most 'Comic' terns occurring in Pembrokeshire pass out of the Irish Sea and along the north coast, passing out to sea once clear of the Bishops and Clerks. Up to 20 pass Strumble Head daily during August and September, with occasional peaks of larger numbers, such as 277 on 3 September 1983 (926 birds were logged in the autumn of 1983, between 12 August and 23 October), and 458 on 27 August 1990 (848 birds were seen passing on the three days from 26 to 28 August).

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

Common Tern - 1994

Passage migrant, formerly bred. Not recorded from November to March

Sage (1956) concluded that the terns mentioned by Ray in 1662 as breeding at Caldey were "almost certainly Common Terns". Mathew (1894) recorded a colony of about 20 pairs on Skokholm Stack which Lockley et al. (1949) believed had ceased to breed in 1916.

Mathew reported the Common Tern as "seen commonly on passage in spring and autumn" and Lockley et al. that it was "now by no means common on passage, when it is chiefly seen in September and October". It has since proved to be sparse in spring, with up to 12 a day seen passing northwards off the west coast and islands between 12 April and 12 June. In the autumn it is more numerous, and has been recorded between 21 July and 28 October, principally off the north coast. The largest recorded count is of 182 passing Strumble Head on 26 August 1990.

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

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 - Spring

terna hirundo/ paradisaea

Spring passage has been recorded from the 29th March to mid June, with stragglers to the end of June, the majority of birds being seen in late April and the first three weeks of May. Most were seen to the west of Skokholm, Skomer and Ramsey, with very few along the north coast but small numbers off the south coast. Most sightings were of one to five birds but up to 18 together have been seen. Those seen moving along the south coast could conceivably have continued their migration up the Bristol Channel and through the Severn valley.

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).

Common Tern - 1894

Species account from M Mathew, 1894, "The Birds of Pembrokeshire and its islands"

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