Lesser Crested Tern: new to Britain and Ireland C. Hurford

n the morning of 13th July 1982, John Chester and I were awaiting the Oarrival of ringers on the beach of Cymyran Bay, Anglesey, Gwynedd, using the time to count recently fledged Arctic Terns Sterna paradisaea that were gathered along the shoreline, when my attention was caught by the presence of a large, yellow-billed tern amongst them. I called John over and, after watching the bird for a short while, he suggested, to his eternal credit, that we had better take some field notes, at which point the following details were noted: SIZE AND SHAPE Considerably larger than upperwing pattern of Roseate 1 era S. dougal- Arctic Tern, though slightly smaller than lii. Underwing appeared generally pale, with Sandwich Tern S. sandvicensis, both of which only trace of darker shading near wingtips. were available for direct comparison. Up­ UNDERPARTS Chin, 'cheeks', throat, breast, right stance recalled that of Sandwich Tern, belly, flanks and undertail-coverts all white. and, at rest, wingtips extended beyond shallowly forked tail. TAIL In flight, appeared very short and barely forked. On one occasion, as bird was alighting on beach, tail was fanned and UPPERPARTS Head heavy and Sandwich looked almost rounded, losing all semblance Tern-like, with dense black cap running of a fork. from base of bill, through eye, and ending at rear of crown in short ragged crest, giving BARE PARTS Bill orange-yellow, length head square-ended appearance. Shoulders, approximately that of Sandwich Tern's bill, mantle, rump and tail uniform medium but heavier and slightly downcurved. Legs grey, noticeably darker than that of Sand­ and feet black. wich Tern. Upperwing: in flight appeared BEHAVIOUR Flight heavy and ponderous (in pale whitish-grey, with three or four dark comparison with Arctic Tern's), No call shafts showing in outer primaries, recalling heard. For the greater part of the time that the bird was present (probably no longer than ten minutes in total), it stood with the Arctic Terns on the shoreline, preening occasionally. It undertook two short flights, each of approximately 50 m along the beach, and, on alighting from the second of these, it stood directly alongside a Sandwich Tern, making direct comparison possible. One or two minutes later, it flew off southwest towards Rhosneigr and was not seen again. Initial thoughts on the identification of the bird turned to Elegant Tern S. elegans, purely on the strength of the knowledge that a tern of that species had been present in Ireland during the period immediately prior to the sighting. Later, on referring to the literature, Elegant Tern was ruled out by the medium grey uniformity of the mantle, rump and tail on the bird that we had observed (Elegant Tern showing a white rump and

396 [Rril. Bird! 82: 396-398. September 1989] Lesser Crested Tern: new to Britain and Ireland 397 tail, and also a deeply forked tail and a proportionately longer, more slender bill). Both Caspian Tern S. caspia and Royal Tern S. maxima were discounted on size and never seriously considered. Cayenne Tern S. eurygnatho was ruled out on the strength of bill shape and coloration and the uniform medium grey upperparts. This left only Crested Tern S. bergii and Lesser Crested Tern S. bengalensis, and Crested Tern was ruled out on size and bill colour. The field notes taken indicated that the bird was in fact an adult Lesser Crested Tern in summer plumage, the combination of size, bill shape and coloration, and the uniform medium grey of mantle, rump and tail eliminating all other species. Since this sighting in 1982, Lesser Crested Terns have been recorded annually in Great Britain, a trend in keeping with that of the Mediter­ ranean countries of Europe, where sightings have been increasing since 1969 (Brichetti & Foschi 1987). Two races of Lesser Crested Tern are recognised currently (BWP vol. 4): the nominate race, which breeds from the Red Sea and East Africa east to Sri Lanka, and S. b. torresii, which breeds in Australia and southern New Guinea, Pakistan and the Persian Gulf, and in the Mediterranean, with large numbers in the Gulf of Sirte, Libya, and one or two pairs in recent years in Italy and Spain. It seems likely that the British records relate to birds of the Mediterranean population of S. b. torresii, which migrates east along the coast of North Africa in spring, having been recorded from Morocco and Algeria to Libya, then moving west again in the autumn. The wintering range remains uncertain, though some are known occasionally to winter along the coasts of Libya and Morocco, and some wintering sites are known in Senegal and the Gambia (also Nigeria in January 1982). The individual observed on Anglesey by John Chester and myself has been accepted by the British Birds Rarities Committee and the BOU Records Committee as the first record of Lesser Crested Tern in Britain and Ireland. The second, on the north Norfolk coast in August 1983 (Brit. Birds 81: 282-283), and a record of Royal Tern in Mid Glamorgan in November 1979 (Brit. Birds 76: 335-339), raised many problems concerning separation of Lesser Crested from Royal, largely resolved with the publication of Harrison (1983), Cramp et al. (1985) and, especially, Gantlett & Harris (1987).

References BMCHETTI, P., & FOSCHI, U. F. 1987. The Lesser Crested Tern in the Western Mediterranean and Europe. Brit. Birds 80: 276-280. CRAMP, S., et al. 1985. The Birds of the Western Palearctk. vol. 4. Oxford. GANTLETT, S.J. M, & HARRIS, A. 1987. Identification of large terns. Brit. Birds 80: 257-276. HARRISON, P. 1983. Seabirds: an identification guide. London & Sydney.

C. Hurford, 5 Westminster Drive, Cyncoed, Cardiff CF2 6RD

Peter Lansdown (Chairman, British Birds Rarities Committee) and John Mather (Chair­ man, BOU Records Committee) have commented as follows: 'Predating this tern record 398 Lesser Crested Tern: nek) to Britain and Ireland were two others which caused much discussion and some differences of opinion: those of a Royal Tern in Mid Glamorgan in November 1979 (Brit. Birds 75: 510; 76: 335-339) and an Elegant Tern in Co. Down injune and July 1982 and in Co. Cork in August 1982 (Brit. Birds 81: 567). During the BBRC's deliberation of this Lesser Crested Tern record came another: a well-watched Lesser Crested Tern in Norfolk in August and September 1983 (Brit. Birds.79: 556; 81: 282-283), which generated even more discussion and disagreement amongst observers than had the previous two records. By late 1983, it was abundantly clear that the larger tems required research and a general clarification of identification features to fill in the gaps in the literature. With the publication of Harrison (1983), letters and notes inBritish Birds (77: 371-372, 372-377; 78: 236-238) and Cramp et al. (1985), the characters of the group began to emerge. This new literature was supplemented by a very full discussion on large- tern identification, and that of Lesser Crested Tern in particular, during the record's three circulations to the members of the BBRC, who unanimously supported C. Hurford's and J. Chester's identification of the Anglesey bird as Lesser Crested Tern. This was endorsed by the BOURC, which was able to comment that the species' escape likelihood was very slight and that its appearance in British waters was to be expected. Acceptance of this Lesser Crested Tern as a wild individual (Brit. Birds 79: 556; Ibis 130: 334) resulted in the species being placed in Category A of the British and Irish list.' EDS