AS the holiday season gets into full swing I always think of the natural history which thrives in and around fresh and sea water.

I enjoyed two long days by the water last week and although I had to put up with some wind and rain there were also generous welcome periods of sunshine.

On Monday I walked alongside the River Wharfe at Bolton Abbey.

Among the picnickers enjoying themselves in the fresh air I saw black-headed gulls, chaffinches and jackdaws begging for some scraps of food.

Families paddled in the river and balanced on the old stepping stones close to the wooden bridge. A family of swans swam lazily along and looked as graceful as a line of old sailing ships.

I also saw pied flycatchers, redstarts and grey wagtails all feeding their young. On Wednesday I went to St Bees Head, in Cumbria, which is now looked after by the RSPB.

I saw common guillemots and, although most had young, there were a few eggs still visible on the rock ledges which I could see by using my binoculars.

Guillemots only lay one egg but, compared to the size of the bird, they are huge.

The pear-shaped egg is placed directly on to the open ledge and there is no nest material.

The egg does not get blown off in the wind because its pear shape allows it to spin like a top.

I wonder if the developing chick gets dizzy?

Converted for the new archive on 14 July 2000. Some images and formatting may have been lost in the conversion.