Friday, 25 November 2011

Continental Greylag Geese

Three of the continental Greylags at Chew Valley Lake.
By Keith Vinicombe

As many people will be aware from the various bird information services, recent weeks have seen a major displacement of Tundra Bean Geese into Britain, as well as flocks of White-fronted Geese occurring in areas where they are not usually seen. However, a third species of goose, Greylag, seems to have fallen below the radar, despite unusual records at a number of places, such as Portland Bill in Dorset.

Being a common feral species, it would be easy to assume that these records lack significance. However, on 17 November, I came across a party of five at Blagdon Lake in Somerset, an unusual record there for the time of year. When I looked at them through the scope, there was something distinctly odd about them, although I couldn’t put my finger on what it was. However, they seemed very fresh and immaculate and both their upperparts and flanks were very heavily barred with white.

A couple of hours later, I was at nearby Chew Valley Lake when, at about 13.30, I heard some Greylags calling. A flock of nine appeared high over the lake and dropped in just to the north of the hide. Their behaviour was strongly suggestive of wild birds and, like those at Blagdon, there was something ‘odd’ about them. I took a large number of digiscoped photographs, and a couple of the better ones are shown here.

Note the pink bills and subtly different bill shape.
According to BWP, there are two subspecies in Europe, nominate anser and eastern rubirostris. Anser occurs in Iceland, Scotland and coastal Norway and has a shorter, thicker and rather triangular bill, predominantly orange in colour (with just some pink behind the tip). Also, it has a pale buffy-grey head and neck and finely barred upperparts and flanks. Our feral breeding birds seem to correspond with this race. Rubirostris, however, is slightly larger and generally paler than anser, with stronger and whiter transverse barring and a longer bill that is wholly pink, apart from the white nail. Birds in central Europe are apparently intermediate.

The Chew birds were indeed heavily and contrastingly barred, they also had longish and rather thin bills, perhaps recalling the bill of Taiga Bean Goose in shape. Their bills were predominantly pink, although at least some had orange at the base. Also distinctive was that the white nail at the tip of the bill was very obvious and contrasting. From BWP, it was clear that they did not fit nominate anser, although, given the orange at the bases of their bills, they did not fit pure rubirostris either. However, they were clearly some way along the spectrum towards that subspecies.

Since then, Nigel Milbourne sent me a good photo of two of the Blagdon birds, and this shows that the left hand one did indeed have an all-pink bill (see ‘Latest news’ at www.blagdonlakebirds.com for 17 November). On re-checking my own photos, it appeared that some of the Chew birds also had all-pink bills. That being the, case, I can’t see any reason why these particular individuals should not be regarded as pure rubirostris. Whatever their exact racial assignment, the important point is that it's safe to conclude that they arrived from continental Europe and were not feral or Icelandic birds. This is the first firm evidence of wild Greylags occurring at the lakes, although the late Bernard King saw a bird at Steart, Somerset, in April 1952 that resembled rubirostris.

Apparently, there has been a big movement of Greylag Geese on the French side of the English Channel, with 200 past Jersey this month and “thousands” past various sites in Normandy. These are thought likely to be Swedish birds deflected westwards en route to Spain (www.guernseybirds.or.gg). It would seem that, like the Tundra Beans and European White-fronts, there has also been a major arrival of continental Greylag Geese - right under our noses!

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