April was ushered in by a raw morning with a chilling east wind. There were at least 30 Herring Gulls on the Serpentine -- not the most exciting of photographic subjects, but this picture does show young gulls of two years. The first year ones are uniformly speckled, and the second year ones have adult grey feathers beginning to appear on their backs.

There was a great deal of noise on the Serpentine island as several pairs of Canada Geese displayed to endear themselves to their mates and deter the others.

They are now so ubiquitous as to be thought of as a pest, but it was not always so. Thomas Bewick's great work British Birds (1797-1804) comments: 'This is another useful species which has been reclaimed from a state of nature, and domesticated ... it is also accounted a great ornament on ponds near gentlemen's seats.'

Of the bird in its native habitat of North America, the book continues, '[They] are also said, at certain seasons, to darken the air like a cloud, and to spread themselves over the lakes and swamps in innumerable multitudes.' It was a while before the British realised that the same thing might happen here.

The two Mandarins on the Serpentine remain in the area between the bridge and the Diana memorial, astounding visitors who have not seen the male's fantastic plumage before. As soon as someone appears with what seems to be a bag of food they nip briskly ashore to collect their toll. These ducks are also descended from ornamental collections and have gone feral. There are a lot of them on the Regent's Canal, where they breed successfully.

A Wood Pigeon was enjoying a bathe at the Lido. This is a native species, of course, but its numbers are increasing rapidly at present.

Still no trace of any Tawny Owls, despite several people searching all over the likely area. The last time one of the adults was seen was on 17 February. The Little Owl also obstinately remained inside the chestnut tree.