An unremarkable day. The Black-Headed Gull from Poland turned up again, for the third day running, and may have decided to stay the winter on the Serpentine. It has had quite a journey for a bird only four months old. Roy Sanderson sent a pісturе оf it to Poland, with an apology that it didn't have Buckingham Palace in the background. I will keep my eye on this bird and see if I can get a better background for the Poles.

Some people were feeding the gulls, amusing themselves (and perhaps also amusing the gulls) by tossing bits of biscuit high in the air. Here two Black-Headed Gulls vie for a flying morsel.

And a young Lesser Black-Backed Gull shakes out the kinks in its large wings.

Here is a young Great Crested Grebe from the nest near the bridge in front of one of its parents. The young birds are beginning to look almost adult, and have grown some ginger feathers to relieve their black, white and grey juvenile colour scheme.

At the same time, their parents are fading into their black, white and grey winter plumage, so these two birds are passing each other in opposite directions. Next year the young birds will have adult breeding plumage, but their first proper crests may be a bit thin and disappointing; it really takes two years for them to reach their full splendour. They will go on getting more deeply coloured every year; if you see a really dark grebe, it's probably an old one.

Here a Song Thrush looks out from grass strewn with dead leaves, whose colour exactly matches its brown back.

Both Song Thrushes and Mistle Thrushes, which are greyer, can become absolutely invisible against this kind of background it they stay still. Their lighter coloured, spotted undersides break up their outline. The American artist and naturalist Abbott Handerson Thayer (1849-1921) was the first person to study this 'counter-colouring', and his observations greatly advanced the young science of camouflage in World War I.

Update: sorry that in early versions of this post the words 'pісturе оf' were turned into a link to some nasty commercial site. This was done by Blogger without my knowledge. I have fixed it by using cyrillic characters for i, c, e and o.