Des McKenzie had arrived in the park early and seen some Golden Plover, a Dunlin, a Snipe and a Woodcock. Arriving slothfully late, I had to content myself with more ordinary birds. But at least the Bearded Tits near the Diana fountain were putting on a good, and well attended, show.

They will get through the cold spell as long as there is a little unfrozen water nearby. There are plenty of seeds on the Phragmites reeds for them to eat, but this dry diet obliges them to drink often.

The other small birds were very hungry, and flocked down to be fed. It is hard being a Blackbird when the ground where you feed is frozen hard and covered in snow.

They are, however, good at finding insects in the leaf litter even when it is under a thin layer of snow, and if you throw them a bit of cheese that sinks into the snow, they will root around and find it. This contrasts with the behaviour of Carrion Crows which, despite their great intelligence, are hopeless at finding things in snow. If you throw a crow a peanut, you have to be careful that it lands in a footprint in the snow so that the bird will be able to find it.

The Pochard-Tufted Duck hybrid turned up on one of the ponds in the Italian Garden. The all-round light reflected off the snow showed that its eyes, which had looked dark brown in earlier pictures, are in fact dark orange, intermediate between the brown of a female Pochard and the yellow of a Tufted Duck.

There were a lot of Pied Wagtails running around the edge of the Serpentine, displaced by the snow from their normal feeding ground on the grass. This first-year bird, still grey and white rather than black and white, was much less shy than Pied Wagtails usually are, and allowed me to get quite close to it although I was obviously following it -- which birds naturally hate.

But it could not equal the amazing nonchalance of the Pied Wagtail in Queensway, which runs around between the feet of passers-by. It was there this morning, and Des was filming it at close range with his mobile when a woman came up and asked him, 'Is that your bird?'

'Yes,' said Des. 'I'm taking my wagtail for a walk.'