The eldest Tawny owlet was just visible in the California bay tree, but so masked by leaves that it was impossible to get a photograph. Judging by the noise made by some Carrion Crows, there were more owls in one of the trees on the south side of the Flower Walk, but I couldn't see them.

The air above the Serpentine was full of Swifts,

Swallows,

and House Martins.

While I was struggling to take these sadly distant photographs, I caught a small falcon in the viewfinder and managed to take some pictures of that too. When it called, it was clear that it was a Kestrel, and when I got home and looked at the pictures, it turned out to be a male one -- probably the bird that I have photographed a few times already in Kensington Gardens.

I was relieved that he didn't catch a bird, though I sympathised with his desire for a good lunch.

Apart from this mild excitement it was a pretty ordinary day. The large number of Herring Gulls persists, and almost every wooden post on the Serpentine had one on it. They are mostly young birds, either coming up to one year old and still with completely tweedy plumage, or coming up to two and beginning to develop a pale grey back. But there are a few adults as well.

This young Grey Heron has just realised that the wire baskets of twigs near the bridge are full of small perch about two inches long.

This is the first time that I have seen a heron on these baskets. The Great Crested Grebes have known about the fish in them for months, but since they hunt under water they can get a better view of the proceedings. The addition of the baskets has proved a boon to the ecology of the lake, providing food for the fish-eating birds. But I am not sure whether they were intended to be fish nurseries; the men putting them in just told me vaguely that they would encourage the growth of organisms that would improve the ecology.