28 January 2014

Nelson's Gulls in Pembrokeshire

Nelson's Gull was first described by H W Henshawe in 1884 and named after the Alaskan ornithologist Mr E W Nelson, who collected the first specimen. Nelson's Gull was first considered a separate species but is now universally agreed to be a hybrid of Glaucous x Herring Gull. It is the commonest hybrid gull on the Eastern Seaboard of the USA so it should be no surprise that it turns up in Pembrokeshire. It is surprising that so few have been recorded, the only candidate before this year being a bird seen at The Gann by Graham Rees in 1984.

With a fine run of 'White-winged Gulls' in Pembs this winter, including no less than five Kumlien's Gulls, it was no surprise that Nelson's Gull has also been recorded. The first, a 2nd or 3rd calendar year bird was found by James Garside in horse paddocks at Simpson's Cross on the 23rd January. This was a big bird, very like Glaucous Gull in size, with a bill approaching adult in pattern, dark eye and with clear buff grey-brown primaries. The bird had a feel of Glaucous about it in bulk and overall plumage tones. It seems most likely a 1st winter but it's possible that the flight photo shows some pale 2nd winter feathering in the wing coverts.

All photos James Garside
I found the second bird at Newgale (of course) on January 27th and quick flight views suggested an immature Glaucous Gull until the dusky primaries became apparent. The bird was very pale, certainly as pale as a young Glaucous Gull. Then as I got better views and some half-decent photos so the extent of dark markings in wings and tail became apparent. The dusky primaries, secondary bar and tail band all suggest Herring Gull whereas the bill, with pink base and 'dipped-in-ink' black tip, overall pale tones and size suggested Glaucous Gull.

The question has to be asked about the possibility of leucism but this seems unlikely. The primaries and secondaries and tail would be creamy I suggest, the bird is too contrastingly pale and dark. The same for the Simpson's Cross bird to a lesser extent. The rather 'patchy' appearance suggests a 3rd calendar year bird, the back seems to be mixed with paler, adult feathering. This also seems to be a Glaucous feature since the darker grey of Herring would be easier to distinguish than it is here. The bird seems to be well beyond the range of a pale Herring Gull. Photos here:

All photos Mike Young-Powell

The third bird of this exceptional period was found by Clive Hurford at Freshwater West on 28th of January. Clearly a second calendar year bird and a bulky beast! showing the typical Glaucous bill. Dave Astins noted the dark overall appearance, especially the underparts, head tail and rump and suggested a strong American Herring Gull influence. It seems pretty certain to me that he's right and given the statement I made earlier about Nelson's being the commonest hybrid gull on the east coast of America and the appearance of all three birds at a time when five Kumlien's Gulls have been seen in the County, it may well be that all three birds are Glaucous x American Herring crosses, just with different combinations of genes and (at least for the Newgale bird) a different age. It's been an exciting time for Gulls hereabouts just lately. The Freshwater West bird here:

All photos Clive Hurford

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