A very cold day, but spring has started and continues unstoppably. A Wood Pigeon was precariously balanced in a bush eating fresh flower buds.

The smaller birds are now appearing in pairs. There were two Goldcrests in a tree on the edge of the Bayswater Road, calling quietly to each other as the traffic roared past. A pair of Song Thrushes were perched in a tree near the Round Pond, looking splendidly spotty but not doing anything very exciting.

In the car park of the Diana fountain, a Dunnock was foraging arround unobtrusively, its quietly coloured plumage camouflaging it against any background, even tarmac.

The Great Crested Grebes at the east end of the Serpentine had just driven the Coots of their nest when I arrived. After a celebratory dance, they contemplated the task of making the nest fit for their own use again, which will involve pulling off all the large twigs that the Coots have piled on it. The nest may change owners several times before one species definitely claims it, and be built up and demolished again and again.

It is not just that Great Crested Grebes prefer small, low-lying nests. With their feet perfectly adapted for swimming but not much use out of the water, they simply couldn't climb on to anything so tall and twiggy.

Coots, on the other hand, are quite agile. I have seen Coots' nests built on a reservoir where the water level fell constantly in spring, so that the nest was left high above the new water level. The Coots built a ramp of twigs to reach the nest, which they had to extend every day until it was at least six feet long, sloping down at an angle of about 45 degrees. They ran up and down this causeway without the least effort.

The female Peregrine was circling high over the Edgware Road -- not a typical Peregrine habitat but usefully full of pigeons.