ENVIRONMENT: OTTERS are probably rivalled only by dolphins as man's favourite mammal. They have been celebrated in films and books such as Tarka the Otter and Ring of Brightwater.

And now they are making a welcome return to the rivers around Swindon.

A new survey by the Environment Agency has revealed that there are at least two otters living on the rivers Ray and Cole, which run through Swindon.

The National Otter Survey, carried out every ten years by the agency, has also revealed evidence of about a dozen of the aquatic mammals in the area of the Thames upstream from Oxford.

Cotswold Water Park and the Thames at Lechlade have both been found to be popular spots for them.

The resurgence in otters has been caused by the outlawing of certain harmful agricultural pesticides.

These nearly wiped out the English otter population in the 1950s by rendering the animals infertile.

Before these chemicals were introduced otters could be found on every river in the country.

Now, the Environment Agency says they are making a major comeback. Some 35 per cent of English rivers and wetlands now have evidence of otters compared with 5.8 per cent 20 years ago.

Agency otter expert Graham Scholey said: "The fact that they are using these rivers close to Swindon shows that they have respectable fish populations and reasonable quality of habitat.

"The chances are slim of seeing them in Swindon but if you are in Coate Water early in the morning keep your eyes and ears open and you might get lucky."

Each otter needs about 10 miles of undisturbed riverbank to live.

Fully grown the European otter, or Lutra Lutra, reaches up to three feet in length and they live for up to ten years.

Environment Agency worker Keith Webb, 57, has manned a lock near Lechlade for the last 33 years. He spotted his first otter three years ago and now there are sightings about once a week.

A self-confessed otter fanatic he said: "They are charismatic and mysterious.

"There is something about them when you see them - it is amazing to think they are in our country.

"It is extremely important to protect them because they are at the very top of the food chain and everything else follows on.

"It is a good sign for other animals, birds and vegetation and for us because we are mammals as well."