When I took this picture I thought it was one of them but on later inspection it turned out to be a Red Kite (thanks to Gregor for pointing this out). These have been spreading southeast from Wales and the West Midlands and are just beginning to arrive in London. This is the third sighting of a Red Kite in the park this year.
On Buck Hill, three Mistle Thrushes were in the rowan trees eating the ripe berries.
So far there has been no sign of the big winter flock of Mistle Thrushes that often visit these trees, but no doubt they will be along soon, and I will keep watching for them.
In the shadow of the Serpentine island, the two Great Crested Grebe chicks were saluting each other with the head-shaking display used by adults.
Is the display hard-wired, or do they learn it by watching their parents? They would be bound to notice it, because the adults greet each other with elaborate courtesy even if they have been separated for a few minutes while one of them is away fishing.
The younger grebe family had returned to the reed bed where their nest is. I could briefly see a couple of the chicks, but it is not a good place for viewing. You have to go some way up the south side of the lake to get an angle where you can see them.
The Coots in the Italian Garden pond were diving for bits of water plant to feed their chicks.
It involves furious paddling, head down, to keep these very buoyant birds submerged. As soon as they stop swimming, they shoot up to the surface.
A Coal Tit was singing in a yew tree in the Flower Walk. August is way past their singing time, of course, but the warm sunshine often brings out a bit of song.