White-winged gulls
I was never happier than when confronted by several thousand gulls on a reservoir roost, in the rapidly fading light of a cold January afternoon, trying to locate a Glaucous or Iceland Gull and to work out which one it might be. If you were overwhelmed by our comprehensive ID guide to these ‘white-wingers’ last month (Birdwatch 342: 32-37), these introductory tips will help you get started.
It is rare to have two species with effectively identical plumages, like a pale European Herring Gull with no black in the wings or tail at any age. You will read that a Glaucous Gull has a flat crown, a square head, an angular nape, and the next one you see will have a head like a tennis ball. Rather, it is the roundness of Iceland Gull’s head – or more particularly its higher crown and steeper forehead – that give it a different look.
You get them best on ‘feel’, but both vary greatly. Two Icelands frequented my local reservoir one winter. One had drooped wingtips and high tertials, giving a characteristic ‘step’, with a little ‘gable end’ between the tertials that created a dark shadow above the white wing-tips: easy to see. The other had long, slender wing-tips that swept up smoothly, with no tertial step at all. But the long wing-tips, held high or low, do help separate an Iceland from a Glaucous.
On juveniles (which stay unmoulted through the winter) Iceland’s wing-tips can be long, upswept and slender in the extreme. On adult Icelands the grey on the primaries often contrasts more with the white tips; it is more blended on most Glaucous – but this doesn’t always hold true.
The bill is the real deal, though hard to see well at long range towards dusk. That of a Glaucous Gull is like a thick European Herring Gull’s bill, and the lower edge sweeps back into a long ‘chin’ before the angle at the throat. On an Iceland, the bill is not necessarily slim, but it is shorter and the ‘chin’ is also very short. The patterns on first- and second-year birds are also distinctive: only an Iceland will show a long dark tip extending back into a point along the middle of the bill. Coupled with the average head shape, the bill is distinctive. Many, though, aren’t quite average.
It is all part of the fun while your fingers freeze on the telescope as the sun goes down. How anyone can say this isn’t the best kind of birding, I can’t imagine. Rob Hume