Another ordinary day with no surprises -- but in this park 'ordinary' means that on a casual stroll around the lake at this time of year you will see about 40 species of bird without the least effort.

There were still a few House Martins hunting over the Serpentine Gallery. They will be off to Africa soon.

One of the three Little Grebes came close enough for a photograph. It was already in its plain winter plumage, having moulted in advance of the other two which are still quite dark.

This second-year Herring Gull has an unusually marked beak with a mottled dark band and yellow showing on the tip. Mostly at this age the tip of the bill is darker than this. Its pale grey adult plumage is already starting to grow in. Next year it will have a completely grey back but its paler parts will still be mottled, in contrast to the pure white of the adult. However, even adults get darker streaks on their head in winter.

Here a Greylag Goose somersaults in a frenzy of washing. The vigorous flapping, tumbling and diving rinses parasites out of their feathers. It is remarkable how a bird this size can dive completely under the surface and stay submerged for several seconds.

And in a moment of sunshine, a Greenbottle fly reveals its beautiful iridescence.