Skua hat-trick

Strong westerly winds have been blowing for the last day or two and this has brought a small number of seabirds into the Severn estuary. Our best site for observing seabirds locally is Severn Beach, a village on the east shore of the estuary just to the south of the Second Severn Crossing. Because of the bridge, most birds blown in are reluctant to carry on upstream, and the estuary is quite narrow here so close views are often possible, especially at high tide.

I visited yesterday evening and again this morning, and the highlight was a pale morph Pomarine Skua (Stercorarius pomarinus) in full breeding plumage complete with ‘tail-spoons’ (like this one). Pomarine Skuas that migrate past Britain in May are on their way from wintering grounds off the west African coast to nest in the Arctic tundra in Russia. Local birder Dave Nevitt first noticed the bird flying upstream at about 8.45am; it gave reasonably close views in the air, and then settled on the water. About an hour later I noticed a second skua, also probably a ‘Pom’, approaching: this bird behaved quite differently, gaining height quite rapidly until eventually I lost it high up. It is possible that it flew inland, and will carry on migrating overland until it reaches the North Sea. Somerset birder Julian Thomas has been theorising about overland skua migration in autumn in recent years and published this interesting note about it in British Birds magazine (scroll down to page 503). I’m not sure if anything has been written about this phenomenon in spring.

The previous evening I had seen two Great Skuas (S. skua) and an Arctic Skua (S. parasiticus), plus two Fulmars (Fulmarus glacialis), two Gannets (Morus bassanus) and at least a dozen Kittiwakes (Rissa tridactyla). Most Arctic Skuas are either pale morphs like this one, or dark morphs like this one, however yesterday’s bird appeared to be an intermediate bird: similar to a dark morph but with paler cheeks and a small pale patch on the belly). The Great Skuas (‘Bonxies’ in birders’ shorthand) came in very close at times, as you can see from the photos on Paul Bowerman’s excellent Severnside Birds sightings blog. Arctic and Great Skuas occur regularly in the estuary after strong winds, and Poms are seen most years, usually in the same concentrated period in early May. Not bad really, considering that we’re a good 80 miles from the ‘proper’ sea. The fourth northern-hemisphere species, Long-tailed Skua (S. longicaudus) is very rare here though.

Other seabirds seen at Severn Beach over the last couple of days include Manx Shearwater (Puffinus puffinus) and Little Tern (Sternula albifrons), but top prize goes to birders at Burnham-on-Sea who had a Leach’s Storm-petrel (Oceanodroma leucorhoa) this morning: these are regular in autumn and winter after storms, but very rare in spring. Good seabird weather occurs quite often through the summer these days, so I’ll no doubt be posting again about this subject before too long.

Brian Lancastle has written two papers about the status of seabirds in the upper Severn estuary: details are on my Articles page.

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