THE expert surveying seagulls in Worcester says the birds are moving inland at such a rate that every town in Britain will have an expanding colony by 2020.

Bird biologist Peter Rock bases his claim on a long-term investigation made of gulls in Bristol, where, in 20 years, the colonies have risen from 100 pairs to more than 1,200.

He has recently been out on Worcester's rooftops helping the council's environmental health department assess its own seagull population.

In 1994, the West Midland Bird Club recorded nine breeding pairs in the city - but early estimates from the most recent survey suggest there are now around 300 breeding pairs.

Mr Rock blames fishing industry changes and the richer lifestyle offered amid urban rooftops for the seagulls' shift from their traditional seaside haunts.

"From a gull's point of view, buildings are simply cliff-sided islands, with no predators and lots of food nearby," he said.

"They happily hoover up the takeaway discards from a human's night out and we even provide them with lighting, to help them find the top pickings."

A good food supply means more city chicks survive, and these birds know that urban areas provide a good place to feed and breed, which gives them less reason to migrate in winter.

As pressure on space grows, younger gulls move further inland and Mr Rock has predicted that within 10 to 15 years it is likely that all Britain's towns will have a growing colony.

To reduce the population in Worcester the council is planning a programme of "egg oiling" where gull eggs are dipped in liquid paraffin to de-fertilise them.