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Thursday, 26 November 2009

A mega of megas - BLACK-BELLIED STORM PETREL in the Severn Estuary

Well my heart-felt condolescences go out to Keith Vinicombe, one of my closest life-long birding friends. Keith was on the phone to me kindly keeping me updated all yesterday morning but despite being on site, frustratingly just could not get himself on to this mega of megas whilst it was in view. Here are the details of this incredible occurrence which took place at Severn Beach on 25 November 2009 -:

Bristol birder John Martin was birding Severn Beach for the third day running due to the storm-like conditions of recent days in the Bristol Channel. He was also joined by four birders from the Wolverhampton area (including Richard Greer) who were keen to see a Leach's Petrel. At around 0820 hours in a fierce Force 6-7 SW gale, an odd petrel was picked up hugging closely the east shore of the Severn, 150 yards south of the southernmost Severn bridge crossing. It was Leach's Petrel-sized but significantly, had striking white underparts and axillaries and underwing-coverts. There was little forking in the tail and its flight was gliding, erratic and low to the sea. It was blackish above, with an obvious white rump, and generally all-white below but with some hint of a thin blackish stripe from the black upper breast to the blackish undertail-coverts. The upperparts were unusually dark and plain and quite unlike typical Leach's with its whitish fringes and tips appearing as a pale diagonal bar on the inner wing from the carpal joint to the trailing edge. Even at long range, the expected covert pattern was not visible and it appeared all dark on the upperparts, perhaps suggesting that the bird was heavily worn. When flying away, the white rump was very obvious. There was perhaps a slight projection of the feet beyond the tail but this feature was hard to see in the blustery conditions. It was either a BLACK-BELLIED STORM PETREL Fregatta tropica or a WHITE-BELLIED STORM PETREL Fregetta grallaria.

It remained on view at very close range for about 15 minutes, gradually getting further and further away mid-channel and being pushed with the incoming tide towards the bridge parapets. It was lost from view at about 0835 hours, just five people witnessing the unique event.

John quickly got the news out as widely as he could and with the knowledge that the tide still had three more hours to come in and this was generally the optimum period for petrel displacement in high winds, birders from the local area quickly descended on the site. The South Atlantic waif must have been sat on the sea for some time as at 0934 hours, it was glimpsed in line with bridge parapet 43 flying back out and battling its way with the wind south. It continued in a line just east of the two marker buoys mid-river being attended by four Herring Gulls which were taking an interest in it. By this time, a crowd had gathered and although very distant by now, a further 14 observers successfully managed to divert their scope lenses on the storm-tossed waif, keeping on it for just over four minutes before it dropped down on the sea at 0939 hours. The Herring Gulls were still surrounding it at this time and with the knowledge that at least 3 of the morning's Leach's Petrels were killed and eaten by gulls, it is not known if this is what happened to it. Despite a constant vigil at the exact area in which it was seen to drop down, it was not seen again, and whether or not the strong tidal surge swept it upriver is unknown. In addition to the original five observers, the later 14 included Mark Ponsford, Gary Thoburn, Chris Craig, Rupert Higgins, Paul Marshall, Dick Reader, Brian Lancastle, Richard Baatsen and David Gibbs.

Sadly, not one image or video was obtained during the two sequences of observation.

A total of 140 observers eventually arrived at the scene, from as far afield as Lancashire, Kent and Norfolk, but despite an all-day vigil until dusk, no more was to be seen of the bird. A total of 14 Leach's Petrels was seen, along with 93 displaced Kittiwakes, a sub-adult Pomarine Skua, a Little Auk and a Grey Phalarope.

Black-bellied Storm Petrel breeds in the South Shetlands, Elephant Island, South Orkneys, South Georgia, the Tristan de Cunha group and Gough Island, Prince Edwards, Crozets, Kerguelen, Antipodes and Auckland, with a total population of some 150,000 pairs. It is nowhere abundant but disperses in winter north to subtropical and tropical waters of all the three oceans and reaches the Northern Hemisphere in the Atlantic and Indian Oceans. There are four records for example off Cape Hatteras in North Carolina.

There has been one previous record in Britain - a Black or White-bellied Storm Petrel seen off Sheringham (Norfolk) on 10 December 2007 (Kevin Shepherd).