Black headed gull - white head in winter?

[belP]

I live near the Thames in London and there are loads of gulls on the river that I think are probably Black Headed Gulls although they don't have black heads. I can't think what else they could be. I've looked up the Black Headed Gull and it says their heads are white in the winter. So how come their heads are already white, surely it's not winter yet...?

[lindapinda]

They're probably this years chicks that haven't developed their black markings yet.There's loads of them around us too.

[belP]

But I can't see ANY with black heads, and I think they did have black heads a few weeks ago.....

[Cetti]

Gull plumage tends to be a bit complicated beLP, but linda is right as the first year chicks start moulting during the late summer, then acquire their 'first winter' plumage.

To make things even more complicated for birdwatchers they have another moult in the spring for 'first summer' then 'second winter' - before finally getting the adult plumage.

Amongst the flocks of gulls an all white head could also mean it's a Common Gull - which is farely rare!

[Noweia]

Black headed gulls have a summer plumage, which is a black head, and a winter plumage which is a white head with a black dot behind the eyes. I've seen a few so far in Scotland with the winter coloring already!

[plowter]

You can tell Black Headed Gulls because they adults have got red bills, with dark tips, and red legs. Their summer plumage includes a dark chocolate brown head, not black. Youngsters have paler bills and legs.

Outside the breeding season the dark head fades until it's a dirty mark behind the eye.

Photos can sometimes help more than descriptions. Have a look at 17:38 Tue 11th Sep 2007

[plowter]

Ooops! Meant to say :

Have a look at Sues Bird Photos. She's got at least 5 pages of BHG photos.

[belP]

Thanks Plowter, I had a look at those pics and the ones without the brown/black head are definitely what I'm seeing on the Thames - red beak, red legs, black spot behind the eye and quite a lot smaller than a Herring Gull. There aren't any with black/brown heads, so they must have all gone into their non-breeding plumage already. Strange that all the descriptions anywhere say they change their plumage in the winter. Or perhaps we've had such a bad summer they think it's winter now?

Thanks to everyone for your comments.

[burnhal]

Its generally called winter plumage but it happens during the post breeding moult which takes place as early as August.