This Black-Headed Gull seen at the Dell restaurant is a Swedish visitor, with ring number 6424936.
It wasn't me who spotted it: I was talking to Alan Gibson, who records and reports numerous gull rings every winter.
A first-winter Common Gull at the Round Pond was beginning to grow adult pale grey feathers on its back.
It takes a Common Gull three years to get full adult plumage. The smaller Black-Headed Gulls manage it in two, and the bigger Herring Gulls and Lesser Black-Backs take four.
On the Long Water, work is now starting on the stone sill to attract waders. This is on the east side of the Vista, a place undisturbed by people and convenient to view across the lake with binoculars or a camera with a long lens. Meanwhile, the workmens' floating skip is moored near Peter Pan. A Moorhen was exploring it.
A Tufted Duck was flying his tuft like a banner as he headed into the breeze near the Serpentine island.
Someone (I would guess Paul Turner, though I didn't see him) had left some dried mealworm pellets on the parapet of the Italian Garden. Carrion Crows are particularly fond of these, and Charlie, Melissa and Kevin had found them. Here is Charlie cramming in as many as he can manage.
As usual, the Jackdaws flew out to meet me at the Round Pond. Here one of them, perched on a stake holding up a young tree, stamps his foot impatiently waiting for his modelling fee of half a digestive biscuit.
The male Tawny Owl spent most of the day inside the nest tree, and it was almost four o'clock when he finally emerged.
The Song Thrush in the Flower Walk was singing again at sunset, high in a tall tree.
Today Great Tits, Blue Tits, a Greenfinch and a Goldfinch were also singing.