An afternoon usefully spent with Nigel Reeve, the Royal Parks ecologist, recording the GPS coordinates of the various trees used by Tawny and Little Owls, and also the dead tree where there is a Treecreeper's nest. The information will now go into the park database, and will be used to keep tree cutting in the area to a minimum. This is particularly important because all the trees in question are old and hollow and likely to be thought dangerous.

The birds were obliging. The Little Owl showed up for a moment in the sweet chestnut tree where I last photographed him on 1 May.

When we went past the reeds on the Long Water where the Reed Warblers are probably nesting, the male gave us a brief burst of song. There are also damselflies in the plants around this spot. Here is an Azure Damselfly -- I think, but insects are not my thing and it might be a Common Blue looking a bit pale.

Elsewhere, the imprudent Moorhens that nested twice in the reeds near the Italian Gardens too close to the edge, and lost their eggs as a result, are having a third try, again too far out. If I can see them to take this picture, so can a hungry gull.

The algae in the Long Water have formed tall towers reaching from the bottom to the surface, a remarkable sight when viewed from the bridge. By looking at them you get a sense of how deep the water is in the middle of the lake, maybe as much as 20 ft allowing for the shortening effect of refraction.

At this point the valley of the former river Westbourne, which was dammed in 1727 to make the lake, is still fairly narrow and V-shaped. Father downstream, in the Serpentine, it opens out into a little plain where once the river meandered through a series of fishponds.