One of the Great Black-Backed Gulls was perched on a post offshore from the Peter Pan statue. It is even bigger than the Cormorant two posts behind it, and dwarfs the Common Gull in the foreground.

When you see one of these birds from a distance, without another bird next to it so that you can't see how large it is, the easiest way to recognise it is by the colour of its legs. Lesser Black-Backs, which look pretty similar, usually have yellow legs -- in the case of this handsome example, absolutely custard-coloured.

However, this is not invariable, and I have seen Lesser Black-Backs with pinkish-grey legs. Usually Lesser Black-Backs are not such a dark shade of grey, and usually they have a slimmer bill in proportion to its length. But even these signs are rather variable.

The visiting Barnacle Goose was on the edge of the Serpentine, standing next to a Greylag. You can see that it is quite a small goose. It is clearly park-bred, as it is very tame and unhesitatingly took a piece of biscuit from my hand.

Why is this bird called a Barnacle Goose? In the Middle Ages it was believed that they grew on trees like fruit, and that the 'unripe' stage as it developed was a barnacle -- a sedentary crustacean which has a 'beak' that looks rather like a goose's bill. For this reason the bird was considered to be a kind of fish, and the church allowed people to eat it on Fridays.

The 14th century traveller Sir John Mandeville, who claimed to have passed through much of the Middle East and even reached China, recounted the legend to some people he met: 'I told them of as great a marvel to them, that is amongst us, and that was of the Bernakes. For I told them that in our country were trees that bear a fruit that become birds flying, and those that fell in the water live, and they that fall on the earth die anon, and they be right good to man's meat. And hereof had they as great marvel, that some of them trowed it were an impossible thing to be.' (Travels, chapter 29)

This illustration is from a bestiary in the Bodleian Library at Oxford, MS. Bodley 764, Folio 58v. How right that unreliable knight's hearers were to trow it an impossible thing.

The two Tawny Owls were in their usual places in the nest tree. There were also two Greater Spotted Woodpeckers and a Nuthatch in the same area -- all birds that nest in holes, in a place full of old trees that provide a profusion of holes for all sizes.