A pair of Lesser Black-Backed Gulls were courting on the edge of the Serpentine. Judging by their behaviour, the male is the one at the back.
I don't know whether these gulls manage to breed in central London, but the closely related Herring Gulls certainly do, on rooftops in Paddington.
A pair of Mallards were also courting, as far as Mallards do court, since their mating is brief and rough. The two bob their heads up and down rhythmically, which is more or less impossible to capture in a still photograph.
A pair of Great Crested Grebes could be seen reserving a nest site on the Long Water opposite Peter Pan.
They use their chosen spot as a place to rest when they aren't fishing, and will defend it against other grebes if they have to -- there has already been quite a lot of territorial squabbling this year. They have been displaying to each other occasionally.But it may be some time before they actually get round to building a nest.
This Little Grebe was in front of the place at the north end of the Long Water where they nested a few years ago, in the reeds behind the netting. The other Little Grebe was nearby.
But they are showing no signs of being interested in each other, at least yet. In fact they are remarkably silent, and may not be a couple. The Long Water is not a good place for Little Grebes to breed, probably because there is not enough cover to shield them from the big gulls. They have done much better in Regent's Park.
The Mute Swans on the Serpentine were doing a lot of menacing and chasing. Here a pair flee from an angry pursuer.
The male Tawny Owl was not out in the middle of the day, and I didn't have time today to wait for him to emerge.