The small but tough family of Mute Swans on the Long Water sallied out on the Serpentine, barging a fishing Cormorant out of the way as they passed under the bridge.

They went on to chase several other swans all the way to the island. Clearly they have designs on a larger territory. Only a few years ago one pair of swans controlled the whole lake and attacked all trespassers: it could happen again.

At the Lido, some other swans were exploring the edibility of some of the border plants, and three of them engaged in a competitive display.

After half a minute the male swan at the front was edged out and left on its own, and the remaining pair -- female on the left, male on the right -- went on displaying. I have seen a dominant male swan break up a couple before, but always on water rather than land.

Today the young Herring Gull's plaything was a lump of concrete covered in algae. It carried the thing around on the water, and dropped it on the edge and picked it up again.

This was was much less fun than the plastic cup it had yesterday (I think it was the same bird, and it was certainly in the same place), so after a while it abandoned its toy and swam away, and I could examine the lump and be sure what it was.

One of the people who records the ring numbers of gulls in the park told me that he had often seen Black-Headed Gulls with consecutive, or nearly consecutive, ring numbers together, and in one case he had seen six Swedish-ringed gulls with close ring numbers in St James's Park. So it seems that at least sometimes these gulls migrate in family groups. It's hard to think of these squabbling birds, for ever trying to steal each other's food, as belonging to families.

The male Tawny Owl was on his balcony ready for his daily photograph.

A Treecreeper was calling in the bushes at the northeast corner of the Serpentine bridge. I had never heard one there before. I managed to get just one reasonable shot as it climbed around in the bushes, and here it is.