A rarity today, but not a bird -- a Monarch butterfly. Tom saw it in Kensington Gardens, moving north from the Queen's Temple, and took this fine picture of it.
John Ferguson, who was with him, actually managed to catch it in flight.
Monarchs are very numerous in North America, but there is also a small population in the Azores, the Canaries and Madeira, and occasionally some get blown up to Britain.
I could only manage a Comma, at the foot of Buck Hill ...
... and a Meadow Grasshopper near Black Lion Gate.
Back to birds. There were three Grey Wagtails in the little pool at the top of the waterfall in the Dell, two adults and a young one, shown here.
The blockage of the water filter at the outflow of the Serpentine has left this pool shrunken, stagnant and smelly, but this has attracted insects, and that was why the wagtails were there. It also didn't stop a Wood Pigeon from bathing in it.
Below the waterfall, the little stream is the only place where the Westbourne river flows above ground. The resident pair of Moorhens have built a nest slap in the middle.
The Westbourne used to be a lively little stream, but its upper reaches in Paddington, Kilburn and Hampstead are now completely paved over and this has reduced the flow to a trickle, so even when the filter is cleaned there won't be enough current to wash the nest away.
The Moorhens in the Sunken Garden have nested for the third time, after losing their two previous broods.
A Starling was bathing in the reasonably clean water of the Serpentine.
The Reed Warblers near the bridge were moving around busily among the stems.
The Mute Swans encamped on the other side of the bridge are taking up more and more of the path. This one lay down in the middle and refused to budge when one of the electric buggies of Liberty drives came along. It irritably bit the front bumper.
The Black Swan is still looking after the cygnet, and the adult Mute Swan seems to have accepted the arrangement.
The male Little Owl in the chestnut tree was being scolded by two pairs of Blackbirds, which annoyed him so much that he retreated to his hole for a few minutes. When they had gone away he emerged, and after looking around carefully flew up to his favourite branch.
While this was going on, a Great Spotted Woodpecker perched for a moment on the top of a wellingtonia near the lake.