The Black Swan was beside the terrace of the Dell restaurant, amusing himself by herding all the Mute Swans out of the little patch of water between the terrace and the floating rafts of plants.

At the other end of this area a Great Crested Grebe was fishing. This is the moment when it starts its dive, by flinging its head down before giving a powerful kick that submerges it. It is a very neat manoeuvre that causes hardly any splash, and if you are not watching closely the bird seems to vanish without effort, as if it had suddenly made itself heavy and sunk.

A young Herring Gull on the south shore of the Serpentine was playing with the largest stone it could lift, which it had fished out of the lake.

Seen just along the shore, this Lesser Black-Backed Gull and Herring Gull are a mixed couple, and have been together for several years. They were calling to each other.

A mob of Black-Headed Gulls were wheeling near the bridge while someone threw food to them.

This Black-Headed Gull in the Italian Garden has a ring coded EX31390. It will have been ringed by Roy Sanderson around 2009 or 2010.

Most birds with rings have been trapped en masse in nets, a traumatic method that risks their being injured in their struggles to escape. Roy ringed gulls individually by throwing bits of biscuit in the air and catching the bird in his hand. The ring went on in seconds and the bird was released, annoyed but unharmed.

There are even more Pochards on the lake, 60 or 70, and also more Red-Crested Pochards -- I saw eight. This drake was preening at the Lido.

As usual, a Redwing was hanging around the rowan trees on Buck Hill, nipping in for a berry while there were no larger birds in the tree.

Most of the Mistle Thrushes were down in the grass, looking for worms in the wet ground.

A Pied Wagtail had also found a promisingly soggy place to hunt in.

This is the hollow area called the Cockpit, near the northeast corner of the bridge, which looks from its shape as if it was created by digging out soil to build up the bridge abutments. The grandstand for the 2012 Olympics was here, and its weight caused the ground to subside, so that it is now constantly flooded.