Wildlife secrets of urban canals to be revealed

With their traditional image as repositories for stolen shopping trolleys and empty beer cans, few would consider Britain's urban canals to be teeming with wildlife.

With their traditional image as repositories for stolen shopping trolleys and empty beer cans, few would consider Britain's urban canals to be teeming with wildlife.

But that is precisely the picture which managers of 2,000 miles of canals and rivers hope will emerge from the first nationwide audit of animal and plant life on waterways.

The initiative announced yesterday will use a combination of expert data gathered by scientists and thousands of sightings by the public to draw up a comprehensive picture of river-based wildlife in both town and country.

British Waterways, which manages two thirds of Britain's river and canals, is asking visitors to the waterways this month to carry out an internet survey of the species they see.

Efforts in recent years to clean up urban canals and rivers are thought to have encouraged rare and endangered species such as the water vole back into towns and cities but little precise data exists to judge the success of the efforts.

A spokeswoman for British Waterways said: "We know that our waterways can provide a haven for wildlife in places where green space is scarce. But we want to be able to provide an accurate picture of just what there is on our waterways. Half of the population lives within five miles of a canal or river so we would like the public to gather the raw data."

Naturalists point to Britain's 3,000-mile network with its hundreds of miles of uninterrupted hedgerow as an ideal haven for wildlife. A rich diversity of species, ranging from bream and bats to molluscs and freshwater sponges, has seen more than a thousand sections of canal and river given protected status.

But waterways are also a battleground for survival, with long-established species facing extinction while new species expand at alarming rates. Last week, the Government published data showing the changing nature of Britain's wildlife populations with species such as gulls, grey squirrels and feral pigeons flourishing to the detriment of others.

The water vole, best known as Ratty from The Wind in the Willows , has seen its population fall from an estimated seven million in the 1960s to just 900,000. The vole population has been reduced by mink, a ruthless predator which has escaped from fur farms.

Ecologists also want to gain a clearer picture on numbers of "alien" species such as the terrapin, (dumped in the wild in large numbers following a craze sparked by the Teenage Ninja Mutant Hero Turtles films) and the American Signal Crayfish - an aggressive invader which is endangering populations of the smaller native crayfish.

Bill Oddie, the television naturalist, who is backing the campaign, said: "It's important to monitor the wildlife that inhabits our waterways, especially those native species whose numbers are threatened."

The data gathered by the survey will become the basis for a national species database which will be shared with agencies responsible for the upkeep of waterways.

Members of the public are being asked to fill in an online questionnaire at a dedicated website: www.waterscape.com.