Nature: Rex Hancy says we can't blame the gull 'visitors' to Norwich for coming here.

The gulls making a nuisance of themselves in Norwich during the summer were, I understand, the lesser black-backed variety. They were merely doing what all creatures do of course. Each species does its best to serve its own interests. That is all very well and all get along quite happily until those self-serving interests clash with those of another species. A moment of thought makes us realise that the species most easily offended and put out of sorts by so many others is our own. After another moment we have to admit that we lay ourselves open to offence by almost inviting troublesome clashes.

Take those gulls as an example. Having depleted their natural food resources, we provide excellent roosting and nesting sites in and on new buildings and then with extraordinary generosity scatter copious quantities of food about the streets. If you are holding a sandwich in your hand and wave it to emphasise a point in your conversation with a friend, can you really blame a gull with initiative taking immediate advantage?

During the summer we had noticed a periodic influx of the large gulls swooping and diving over our gardens before taking short breaks next the chimney pots. One day a solitary gull swooped past my head as I stood by the fence. Eddie said a scrap of food was visible on the grass quite distance away. The one turned into five. Then there were ten. After that any count was impossible as they wheeled and weaved, shrieked and cried. None was brave enough to come to ground and take possession of the free gift. Had it done so we were sure it would have been chased and harried by its less than comradely companions. After the whole flock gave up to try its luck elsewhere, a wily crow who had cannily watched the whole performance popped out of the birch tree and helped himself in a cheeky, leisurely fashion.

Weeks passed by during late summer and early autumn without a gull in sight. One day I was told the gulls were back. But no, these were the much smaller, more slender black-headed gulls. Of course, they were wearing their white head feathers, as they do in winter. Aggravating, aren't they!