Red-billed Tropiebird in Suffolk Alan Knox, Howard Mendel and Nigel Odin n 17th February 1993, following a report of bird carcases on the shore­ Oline at Landguard Point, Suffolk, the area was surveyed by NO. A few emaciated Common Guillemots Uria aalge were found and, on part of the Harwich harbour shore inside the spit, the carcase of a Red-billed Tropiebird Phaetimn aethereus was discovered. It was on the third tideline up the beach and would have been washed ashore at least* 36 hours previously. Although the eyes were sunken, the carcase was in good condition and had somehow escaped the attentions of tideline scavengers.

Examination of the specimen The specimen was prepared as a study skin with one wing partly spread (Ipswich Museum R. 1993-19; plate 125). X-ray and visual examination of the trunk after skinning revealed that the left coracoid had been dislocated from the sternum and the anterior end of the sternal keel had recently been frac­ tured. It is unlikely that these injuries would have occurred during the prepa­ ration of the specimen. The skeleton of the trunk was preserved (Natural History Museum, Tring, S/1993.36.1). Some of the plumage was contaminated widi oil, particularly on the neck. A sample of the soiled feathers was sent to the Institute of Offshore Engineering at Heriot-Watt University for analysis. Although it was not pos­ sible to determine the precise origin of the oil from its biomarker fingerprint, the oil was considered to be probably a medium/heavy fuel oil and it was still fairly fresh, having been exposed to the elements for only one to five days, depending on the weather. The oil showed signs of physical weathering, but there was no evidence of microbial degradation. The analysis suggested that the oil was probably not from a slick and was more likely from a drop in the water or from the deck of a ship. The bird was sexed internally as a female, with an ovary about 8 mm long. The ova were indiscernible, probably because the tissues were starting to decompose. The gizzard did not contain any fresh food, but several small fish vertebrae, fish scales, two otoliths (fish ear bones), a fish eye lens, a small

488 \linl. «»rfv 87: 488-491. Orlohcr I994| Red-billed Tropicbird in Suffolk 489 squid beak and various other remains were recovered. Of the items which could readily be identified, die otolidis and vertebrae had come from a flying- fish, most likely of die genus Hirundichthys, and from an individual probably about 12-19 cm long. The otoliths were more highly eroded than is usual for food remains in bird gizzards, suggesting that they had been in the tropic- bird's gizzard for a long time.

Description Generally white, with heavy black bars on suggest that the bird was immature. Contour feathers on upperparts. Head: white with solid feathers apparently very fresh. Most wing black in front of eye, becoming more broken feathers fresh, although a few inner behind eye and broadening on nape. Dark secondaries, inner greater coverts and other areas on primaries and inner secondaries jet- inner coverts very worn and much browner. black. Outer primary coverts all black, lacking Tertials fresh. Bill orange-red with clear black white on outer edges or tips. Lower lesser on die cutting edges, the tip and around the coverts black with only narrow white tips, the nostrils. black forming an extensive bar on inner wing; MEASUREMENTS Left wing 290 mm, right wing upper lesser coverts with whiter bases, centres 293 mm, tail 195 mm, exposed culmen 60.5 and edges, though still heavily marked. The mm, bill depth 20 mm, weight at time of heavy markings on the upperparts and head preparation 540 g.

Racial identification The plumage differences between the subspecies of Red-billed Tropicbird and their geographic ranges have been summarised by Knox (1994). The two Atlantic races (one of which also occurs in die eastern Pacific), aethereus and mesonauta, are significantly larger than indicus from die Red Sea, Persian Gulf and Arabian Sea: wing 296-330 mm, bill 59-66 mm (both sexes) on aethereus and mesonauta, compared with wing 267-315 mm, bill 52-62 mm on indicus (Cramp & Simmons 1977; Brown et al. 1982). The small size (particularly wing length) of the Suffolk bird, the distinctive wing markings (especially the heavy black bar on the lesser coverts) and the characteristic bill colouring all indicate that the Landguard specimen belongs to the race indicus, rather than either of the two Atlantic subspecies. The bill length of die Suffolk bird is, however, not diagnostic. Bill depth was measured on skins at The Natural History Museum, Tring. For aethereus and mesonauta

125. Red-billed Tropicbird Phaethon aethereus, Suffolk, February 1993. Specimen now at Ipswich Museum (A. G. Knox) 490 Red-billed Tropicbird in Suffolk the bill depth was 21-23 mm (both sexes, n = 17), compared with 18-22 mm (n = 16) for indicus. The Suffolk bird's bill depth, at 20 mm, therefore fits bet­ ter as indicus than as aethereus or mesonauta. Identification of the bird as belonging to the race indicus is contrary to an earlier determination (Anon. 1993), even though the plumage and bill colour arc clearly visible in the photograph accompanying that article.

Discussion There are no accepted records of Red-billed Tropicbird for Britain, or, indeed, for northwest Europe. Two old records from England were recently reassessed by the British Ornithologists' Union Records Committee, but neither was found to be acceptable (BOU 1993; Knox 1994). The occurrence of the species in the Western Palearctic has been summarised by Knox (1994). This includes a tidclinc corpse found in the Netherlands on 27th January 1985 (Bruinzcel 1986). It had fresh flying-fish in its stomach and the origins of the bird arc considered to be obscure. It has not been accepted onto the Dutch list. Tropicbirds often feed at night, frequendy making use of the lights from ships to catch squid and flying-fish. At such times, they arc liable to crash-land on deck after colliding with the ship (Tuck 1978; R. Burridge verbally). Such birds that come aboard at night are often uninjured, but they invariably try to hide in some quiet corner and have great difficulty taking off without assis­ tance. Once under a container on deck, a bird would be well protected from the elements until the corpse was found during unloading or when the decks were being washed down. The carcase would then be dumped overboard either in harbour or shortly after leaving port (R. Burridge verbally). Landguard Point at die southeast corner of Suffolk is a shingle spit protect­ ing the mouth of the Orwell Estuary. The point is adjacent to the container port of Felixstowe, and shipping heading to the nearby ports of Ipswich and Harwich (Parkcston Quay) also passes close by. It is most likely that the tropicbird crash-landed on a ship probably bound for Felixstowe and died on board. The injuries noted above may have occurred when die bird collided with the ship or crashed to the deck. The carcase presumably went over the side near the port and was brought ashore on the inside of the spit on the next tide. Where the bird came aboard the ship is not known, but its racial identification and the flying-fish remains in the gut strongly suggest that uiis was not in British waters. The oil on the plumage may have been picked up on the deck of the vessel. The nearest part of the normal range of indicus is the Red Sea. If the bird had come aboard a ship there, it might have remained alive for a few days and then the cool February weather may have slowed the decay of the corpse. A container ship would take six or seven days to travel from the eastern Mediterranean to Felixstowe. Red-billed Tropicbirds have apparendy occurred several times at Le Havre, France, or on ships headed there (Vincent 1993), although none of the records has been accepted. Perhaps it is only a coincidence that one of the records was in January 1993, but it is interesting to note that the Dutch tideline corpse was ;dso in January. Red-bilkd Tropicbird in Suffolk 491 Sub-category D3 of the British & Irish list (see BOU 1992) is reserved for species that have only been found dead on the tideline. Category D is not part of the main list. D3 is intended for species that may or may not have arrived alive, and naturally, in British or Irish waters. It seems most unlikely that tlic Landguard tropicbird arrived within territorial limits either alive or naturally. The record has not been submitted for possible inclusion in cate­ gory D.

Acknowledgments We should like to thank Bob Burridge, a Merchant seafarer and ornithologist, for his observations on tropicbirds from and on ships. S. J. W. Grigson at the Institute of Oflshore Engineering car­ ried out the analysis of the oil, kindly arranged by D. J. Lampard. The food remains were identi­ fied by Oliver Crimmen at The Natural History Museum, Dr Werner Schwarzhaus and Alison Locker. We are also grateful to The Natural History Museum, for access to skins and the library at '['ring. Tim Inskipp, Peter Lansdown and John Marchant made helpful comments on the manuscript.

Summary A dead, probable immature female, Red-billed Tropicbird Phmthon adherens was found on the tide- line on the Orwell River side of Landguard Point, Suffolk, on 17th February 1993. When discov­ ered, the bird was in good condition and apparently uninjured. The skin and part of the skeleton have been preserved. The tropicbird belonged to the race indicus, normally found in the Red Sea, Persian Gulf and Arabian Sea. Bones from a flying-fish (Exocoetidae) were recovered from its gut. The bird's plumage was lightly oiled, apparently with fuel oil. It is suspected that the bird may have landed on a container ship in the Red Sea and subsequently died and that the body was later dumped overboard in or near Felixstowe. It would be inappropriate to include this record in sub-category 1)3 of the British & Irish List (reserved for tideline corpses of unknown origin), as it seems most unlikely that the bird arrived alive, or naturally, in British or Irish waters.

References ANONYMOUS. 1993. Titbits: Red-billed Tropicbird. Birding World 6: 61-62. BOU. 1992. Checklist of Birds of Britain and Ireland. 6th edn. Tring. 1993. Records Committee: nineteenth report. Ibis 135: 493-499. BROWN, L. H., URBAN, E. K., & NEWMAN, K. 1982. The Birds of Africa, vol. 1. London. BRUINZKKL, L. W. 1986. Roodsnavelkeerkringvogel bij Egmond aan Zee in januari 1985. Dutch Buirng 8: 45-48. CRAMP, S., & SIMMONS, K. E. L. (eds.) 1977. The Birds of the Western Pakarctk. vol. 1. Oxford. KNOX, A. G. 1994. Claimed occurrences of Red-billed Tropicbird in Britain. Brit. Birds 87: 480- 487. TUCK, G. S. 1978. A Field Guide, to the Seabirds of Britain and the World. London. VINCKNT, T. 1993. I^es captures et observations de Grands Phaetons (Phaethon atthmus) sur des navires faisant route vers Le Havre (Seine-Maritime) depuis 1925. L'Oiseau et RFO 63: 130-133.

Dr Alan G. Knox, Buckinghamshire Count)! Museum, Tring Road, Nation, Buckinghamshire HP22 5PJ Howard Mendel, The Museum, High Street, Ipswich, Suffolk IPl 3QH Nigel Odin, Landguard Bird Observatory, View Point Road, Felixstowe, Suffolk IP11 8TW