Two of the young Mandarins were flying today -- earlier than I expected, as their wing feathers are not quite fully grown. They came down on the Long Water near the bridge, as efficiently as if they had been flying for years, and climbed up on to the grassy bank.

It is still not clear how many of the original four have survived, as they are moving round independently and you never know whether you are seeing the same one twice. But it is a great achievement to have any on the lake, which is not nearly as good a breeding ground as the Regent's Canal with its fenced-off, unvisited banks and few big gulls.

The eldest pair of Great Crested Grebe chicks were chasing their parents up the middle of the Serpentine to the bridge, undeterred by the ridiculously oversized jetty that is being built in the lake for a triathlon. At the other end of the lake, it was feeding time for the three younger chicks.

The parent had to offer this largish fish to the chicks several times before one of them managed to swallow it.

A large flock of Long-Tailed Tits was working its way through the bushes at the bottom of Buck Hill. This one paused for long enough to have its photograph taken.

They were travelling with some Blue Tits and at least one Chiffchaff. These mixed foraging flocks are common in winter, and it seems that any small insectivorous bird can join as long as it has the right flocking behaviour and warning calls to avoid collisions.

No sign of the Hobbies for several days now: the may already have set off to Africa. I got a brief glimpse of a small falcon, also on Buck Hill, but the weak sunlight falling on its back gave a reddish reflection, so it must have been a Kestrel.

I went up to the Round Pond to see how the young waterfowl were doing. There were five Mallards, grown almost to full size, and six Egyptian Geese. And there were at least 200 Black-Headed Gulls, sitting on the water in dense crowds.