Late on the evening of November 25th 2000 south westerly winds began to pick up in strength, quickly reaching gale force. The ensuing storm continued throughout the night and into the following day; of note, the highest wind speeds recorded were in the Bristol Channel

With these weather conditions prevailing I decided that an early morning 'sea watch' at Severn Beach was called for as the high tide was at 07:15. I arrived at Severn Beach at first light, ever optimistic of finding an unusual seabird but even by Severn Beach standards the first couple of hours until nine o'clock were exceptionally unproductive. Paul Bowerman had found a winter- plumaged Mediterranean Gull, and an adult Kittiwake had drifted to the south-west with the ebb tide.

Just after 09:00 I was about to give up when a large shearwater came into view. It was moving up-channel towards the Second Severn Crossing, and was in the company of a couple of Herring Gulls. They were close inshore, at most two hundred metres from the shore, and it was immediately clear that the large shearwater was in fact a Cory's Shearwater (Calonectris diomedea). The shearwater, upon reaching this area of the Severn Estuary, drifted further from the shoreline and, rather than fly under or over the new bridge, turned and slowly flew to the south-west. It was at Severn Beach for some three to four minutes before being lost to view.

Remarkably, this individual's progress from the Severn Estuary and Bristol Channel was well charted, largely due to the use of mobile phones and pagers. It is not inconceivable but highly unlikely, given the scarcity of records of this species, that more than one bird was involved in the subsequent series of sightings.

Paul Bowerman and Dick Reader were also present at Severn Beach and also saw the bird. Subsequently, it was recorded at the following localities: in North Somerset, from Clevedon Pier at 10:05 by Paul Chapman, an hour later at Sand Point by Rich Andrews, then at Anchor Head, Weston-s-Mare at 11:15 by Pete Gregory; then in Somerset, Mark Ponsford saw the bird from Brean Down at 11:25, and finally it was reported off Minehead at 13:40.

Description

This was a large, rather long billed greyish-brown shearwater. The overall size seemed to be about that of Herring Gull, two were initially accompanying it, hence a direct comparison could be made. The shearwater's long, narrow wings added to the overall impression of size. Characteristically, when in flight, the wings were usually held in a bowed attitude and were angled slightly backward at the wrists.

The upper parts and upper wing were a uniform greyish-brown colour with the primary feathers being darker, a noticeable narrow whitish band was present on the upper-tail coverts, a feature not always present in the species and one which is shared with Great Shearwater Puffinus gravis.

The crown, nape, ear-coverts and sides of the breast appeared greyer than the rest of the upperparts. A darker smudge was also noted on the face, this smudge extended through the eye and onto the ear-coverts. The tail was dark brown.

The under parts and under wing were generally pure white, but less distinc­tively so on the breast and throat, merging with the greyish tones of the head. The axillaries and under wing-coverts were white. The leading edge of the under wing, the primary and the secondary feathers formed a dark border to the white of the under wing-coverts.

Bare parts: The bill was typically rather long, very pale and a 'dirty' yellow­ish colour with a dark tip. The coloration of legs/feet was not noted; clearly they did not contrast sufficiently with the rest of the under parts.

To summarise, the size of this bird precluded the smaller shearwaters; Great Shearwater could be readily eliminated by the lack of a capped effect and pale collar.

Additional Notes

Cory's Shearwater is exclusively a Western Palearctic breeding species and out­side the breeding period it ranges across the North Atlantic and into the Southern Atlantic as far as South Africa, some reach the waters off the coast of South America.

Most records for the British Isles occur in late summer during July and August. Occasionally, given the right weather conditions, large numbers are seen at this time of year, particularly near Porthgwarra (Cornwall) and off Cape Clear Island in County Cork.

There are three recognised subspecies, the nominate diomedea inhabits the Mediterranean; borealis is from the subtropical east Atlantic and edwardsii from the Cape Verde Islands. The taxonomy of these three races is still the subject of much debate, the latter subspecies, edwardsii, is significantly distinctive to war­rant being considered for full species status as Cape Verde Shearwater. However, a recent paper published in Dutch Birding in 1998 (Volume 20, No. 5) described the differences between the other subspecies, diomedea and borealis, which had previ­ously only been thought safely separable by measurement; the former being the smaller. This article highlighted many of the more subjective characteristics sepa­rating these taxa, but it also pointed to a quite significant distinguishing feature on the under wing pattern. In diomedea the inner webs of the outer primary feathers are white along most of their length, the white extending to near the feather tips. Whereas in borealis the primaries are uniformly dark giving a completely differ­ent effect, a feature, which when given reasonable viewing conditions is noticeable in the field. The article also proposed renaming the nominate race diomedea as Scolopi's Shearwater; Cory's Shearwater being used to describe borealis.

P. Chapman was the first to point out that the Severn Estuary and Bristol Channel bird could readily be ascribed to the Atlantic race borealis by using the foregoing identification criteria.

This was the first record of Cory's Shearwater to be accepted in the Avon area. However, on August 26th, 1986, R. Angles observed three large shearwaters moving down-channel off Anchor Head, Weston-s-Mare, which he believed to be Cory’s, but the brief views and distance precluded positive identification. Some substantiation can be given to this record as on the same day three Cory’s Shearwaters were seen heading south off Berrow, Somerset; the third record for this county.

Previous records for the Bristol Channel & Severn Estuary

Somerset: Parrett Estuary, Sept. 11th and 19th, 1983; Berrow, three Aug. 26th, 1986 (see above); Minehead, Sept. 6th, 1987; Porlock Bay, July 17th, 1994. Monmouthshire: Peterstone Pill, Sept. 7th, 1983. South and West Glamorgan Sker Point, July 27th, 1975; Nash Point, June 12th, 1991; Port Eynon Point, Aug. 18th, 1983, Aug. 3rd, 1984, July 28th, 1999, there was also an unconfirmed report from this locality on June 9th, 1998.

Brian Lancastle - November 2000.