WILTSHIRE is among the areas in England where the otter is returning in numbers after being driven from its habitat nearly 50 years ago.

The Wiltshire Wildlife Trust revealed this week that county populations of the aquatic mammal have recovered.

The National Otter Survey for England, published on Monday, the fourth survey of its kind since the late 1970s, has found that the area otters now live in has increased five-fold in the last 25 years.

The survey investigated the distribution of the otter throughout England during 2000-2002. Of the 3,327 riverbank and wetland sites surveyed, just under 35 per cent showed evidence of otters, rising from less than six per cent nearly 25 years ago. The practical survey was largely undertaken by otter conservationists of Water UK and The Wildlife Trusts' Otters and Rivers Project. It was analysed and written by the Environment Agency.

One of the conservationists involved was Wiltshire Wildlife Trust's otters and rivers project officer Mark Satinet. He said: "Otters have made a comeback right across Wiltshire. Almost one out of five sites covered in the survey had signs of otters.

"The fact that otters now live along many of Wiltshire's rivers and canals is fantastic in itself, but it is also welcome proof that our efforts restoring riverbanks, building artificial otter holts, and working alongside landowners and water companies to make the rivers cleaner and healthier really are succeeding."

Mr Satinet said he had visible proof of this last autumn when he came face to face with an otter in the wild, on the River Ray near Swindon, the first one in nearly a decade of work on Wiltshire's rivers.

Otters are now regular visitors on many of Wiltshire's best-known rivers and waterways including the Kennet and Avon Canal, the Bristol Avon, the Salisbury Avon, Wylye, Nadder and the Upper Thames. Otter signs have been observed in towns such as Chippenham, Salisbury and Swindon as well as in the countryside.

The otter, one of the UK's most charismatic and best-loved mammals, suffered serious decline in the 1960s, primarily following the widespread use of toxic pesticides, such as Aldrin and Dieldrin. By the mid 1960s the UK's once-thriving population had been reduced to remnant populations in the south west of England, East Anglia, parts of Wales and Scotland.

The otter's comeback is based on a combination of factors including enhanced water quality, local improvements in fish stocks and changes in riverbank management.

The otter is an important indicator of the health of rivers and wetlands.

The survey's author, Andrew Crawford of the Environment Agency, said: "The otter is on the road to recovery. The survey suggests a real increase in otter range, which in turn reflects a considerable increase in population."