There were a lot of Cormorants on the lake. Some had arranged themselves on the fallen horse chestnut tree on the Long Water ...
... this one was reclining on a post by the Serpentine island ...
and others were trawling in gangs. It is a sign that the fish population of the lake is quite high -- except that when the Cormorants have finished, it's much reduced. Large influxes in past years seem to have fished so efficiently that they reduced the population of medium-sized fish to negligible proportions, after which they left to try their luck elsewhere.
The Great Crested Grebes on the Serpentine had to run the gauntlet of Black-Headed Gulls to feed their chicks. This fish did actually reach the chick without getting snatched, but only after both parent and chick had dived and come up in a different place, which momentarily blindsided the gulls.
This meal, on the other hand, was only suitable for adults. I am still not sure how the grebe managed to swallow this large crayfish, legs, claws and all.
As the Mallards recover from eclipse, some of them remain puzzling. This one appears to be male, judging from its yellow bill.
But I haven't seen this individual in full breeding plumage; it seems to be a new arrival. My guess is that the feathers on its body will turn out black, leaving the white neck patch, as this pattern is quite prevalent among Mallard drakes when the pattern of their plumage is disturbed by some genetic factor.
Andy Sunters drew my attention to a good blog on bird behaviour, 'The Rattling Crow'. This is a subject of great interest to me, and I shall be following it.