The Great Crested Grebe family from the Serpentine island have emerged from the shelter of the wire baskets, and for the first time it was possible to see that there are three chicks. Two of them can be seen riding on their parent's back, and the top of the third one's head is just visible on the far side of the right-hand chick.
Carrying babies around makes a dreadful mess of the parents' wing feathers, but they moult them soon afterwards and grow fresh ones while they are still lake-bound looking after their young and do not need to fly.
In the swimming area at the Lido, four large men were thrashing up and down the length of the buoyed-off area. In the midst of them a grebe was unconcernedly fishing. Perhaps the swimmers disturb the fish in a useful way that makes it easy for the bird to catch them. It is quite fast enough in the water to be sure of dodging flailing human arms and legs.
A Reed Warbler flew up from the reeds near the bridge and landed in a nearby oak tree, where it hopped briskly around in the foliage, presumably hunting for insects.
Young Carrion Crows have emerged. Here, one struts about jauntily on the edge of the Serpentine. Juvenile birds have blue eyes and look slimmer than adults as they have not yet grown the thick mane of feathers round the neck which gives an adult crow its characteristic shape.
Here another two young crows beg noisily for food.
Update: Peter Tang reports seeing a Great Black-Backed Gull. I missed this myself. Here is a picture of one I took in 2008. They are very large indeed, and have pinkish-grey legs like Herring Gulls rather than the yellow legs of Lesser Black-Backs.