The Black Swan was at the landing stage near the Diana fountain, with girlfriend number one.
Later he moved off to where someone was feeding the birds, and the girlfriend went under the bridge on to the Long Water. She soon came scooting out, as the dominant male Mute Swan has now cleared his lake of all intruders and was patrolling menacingly back and forth along the bridge.
Two pairs of Great Crested Grebes were also having a territorial dispute on the Long Water.
The pair at the east end of the Serpentine were rebuilding their nest, damaged by yesterday's wind and waves. The reed rafts, which are anchored with inadequate bags of stones, had shifted and the nest site now has a fence close to both sides.
Nearby on the shore, a Magpie was having a brisk wash.
There were six Mandarins at Peter Pan.
I heard that Herring Gulls and Carrion Crows were pulling up the newly laid turf on the Parade Ground to look for insects and worms underneath. I found quite a lot of pulled-up turf but couldn't catch them at it. But there was a Pied Wagtail also looking for insects on the edge of a flooded area.
The Parade Ground is on a gentle slope and you might not expect it to flood, but there is only a thin layer of soil on top of an impervious expanse of London clay, and the drainage can't cope with even moderate rain.
The two promised Tawny Owl boxes have been put up. A quick visit found only one of them, on a tall horse chestnut a few feet north of the owls' original nest tree.
It's a handsome structure and would be a desirable residence for any owl, but will they like it? Are they nesting already in a hollow tree somewhere? No one knows.
Update: The London Bird Club Wiki has a brief note from Charlie Farrell, put up on Wednesday but I missed it then. He saw a Tawny Owl flying from the area of the old nest tree to the leaf yard. Also, Paul tells me that the other owl box is on a nearby lime tree.
At least we know where three pairs of Little Owls are. This is one in the tall lime tree near the Henry Moore sculpture.
And here is one in the oak tree near the Albert Memorial. It didn't come out till late afternoon.