A rainy day has its compensations. With few people in the park, there is a chance of something interesting happening.

As I was walking along the path from the west side of the Vista to the leaf yard, a Grey Heron came flying in the opposite direction at head height, passing within inches of me. In its beak it held a rat, screaming with terror. I ran back after the bird to see if it had perched on one of the posts at the Vista to devour its prize, but it had retired into the bushes. I have seen a heron eat a rat before: holding it by the tail, flipping it up in the air to turn it round, and neatly swallowing it head first. A violent end for a rat, but far better than a lingering death from poison put out by the park keepers.

As I was feeding the small birds in the leaf yard, the heron returned to stalk another rat. It almost succeeded. In this picture it creeps delicately up on its prey (arrowed) ...

But before it can seize the rat, a couple of crows turn up to chase it away. Not to save the rat, of course, but because crows hate herons and lose few opportunities to harass them.

There was a Reed Warbler singing in the reeds on the Long Water near the south end of the bridge, the first I have heard this year. Don't expect a photograph of this wonderfully elusive bird. In all my life I have seen one for a total of 15 seconds.

Large numbers of Greylag and Canada Geese, having come to the lake to moult their flight feathers, were grazing peacefully on the grass south of the Serpentine, undisturbed by the dogs of visitors who had stayed indoors out of the rain.

The Greylags moult first, and some already had no flight feathers visible at all. The new feathers grow from the same follicles as the old ones, pushing the old feathers out as they grow, and emerging in neat packages wrapped in what looks like blue plastic sheet which split to release the feathers.

Elizabeth has made a charming slide show of a family of Egyptian geese settling down for the night.