There is a mixed pair of gulls in the southeast corner of the Serpentine: a second-winter Herring Gull paired with an adult Lesser Black-Backed Gull. They have been together for at least a week. Today I found them displaying to each other.

Mixed pairs of gulls are not uncommon. In the case of Herring Gulls, Lesser Black-Backs and Yellow-Legged Gulls, the offspring are fertile, so that there are quarter- and eighth-breed guls before the minor species becomes unnoticeable. All these species are so closely related that it is tempting to consider them different races of a single species. But even the official species are divided into races: most of the Lesser Black-Backs we see are Larus fuscus graelsii, with slate-grey backs, but there is also the dark grey Scandinavian race L. f. intermedius and the black Baltic race L. f. fuscus.

Just along the shore from this couple, a foolish woman had let her expensive Italian greyhound go into the lake where there was a group of Mute Swans. The swans united to repel the intruder.

Dogs often kill swans on the grass around the Round Pond. But if the dog is in the water, the swan is boss -- and you can see that these birds know it. Swans hate dogs, for obvious reasons, and will make a beeline for any dog that has had the temerity to intrude on their patch.

The solitary Barnacle Goose is still here, and I found it walking down from feeding on the Parade Ground to have a drink in the Serpentine.

It is very tame and took a piece of biscuit from my hand. No one knows where it came from.

The east side of the Vista is sometimes called the Rabbit Paddock, and rabbits were numerous here until the outbreak of myxomatosis a few years ago. So, of course, were foxes. The rabbits have been very slow to recover from the outbreak. But today there were three young ones on the Vista.

They may be cuddly fluffy bunnies, but if you are used to the alertness of birds they seem terribly inert and dull. They just sit there chewing.