Roy Sanderson cleared up the mystery of the sudden appearance of two Mandarins, one of which was still regrowing its wing feathers and unable to fly. Mandarins sometimes spend time out of the water, he told me. So this pair has probably been lurking unseen in the shrubbery.

He also thinks that the five recently arrived Gadwall may have come from Regent's Park, not Buckingham Palace Gardens. There is sometimes a breeding pair of Gadwall in the palace gardens, but not this year. There are only an estimated 790 breeding pairs of Gadwall in Britain, and most of the ones you see are winter visitors. That is, by the way, more than the number of Common Pochard, which are constantly seen in the park. The national count of breeding pairs for these in 2010 was 339 -- not common at all.

The number of Cormorants on the lake is holding steady at about 10. They fly in for a day's fishing and return to the river, and the cross-shaped outline and steady wingbeat of a Cormorant is a frequent sight in the London sky. Here one dives in the Long Water.

One of the young swans had contorted itself into a strange shape while preening in the gusty wind.

But the master contortionists are Great Crested Grebes, which get into every conceivable attitude. Their highly flexible neck, with 21 cervical vertebrae, allows them to turn their head through 520°, and I have seen a grebe turning its head round to the left to preen the right side of its neck.

Starlings are inordinately fond of potato chips. The Lido restaurant serves fish and chips, and the birds will make daring raids to grab them. When the Starlings are nesting on the other side of the lake, they will fly right across the water for a chip and bring it back to their nestlings.