Tuesday 20 October 2009

Dark-tailed Herring Gulls, Peterhead

Winter gulls are arriving in the region, and with them the usual mix of pale and dark Herring Gulls. Here are a couple of examples of dark-tailed Herring Gulls photographed on 11 Oct at Peterhead. Both show very well marked rumps and upper tail coverts, and extensively dark tails. Neither bird shows a tail band per se; rather they have wholly dark tails with white speckling restricted to the outer 3 retrices. This tail and rump pattern is easily within the range of variability exhibited by Amercian Herring Gull (L. smithsonianus) (e.g. see Figure 1 in Lonergan and Mullarney, DB 26 (1), 2004) . We do not currently know where such birds come from. Although dark tailed, other plumage features of these Herring Gulls did not match smithsonianus.

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