How UK's industrious otters have reclaimed the urban waterways as their home

Efforts to clean up rivers and canals have allowed an animal that is normally reclusive to live and breed in city centres

You've heard of the urban magpie and the urban fox. Now stand by for the most remarkable example yet of wildlife moving into our towns and cities – the urban otter.

A survey by the Wildlife Trusts has found that otters are starting to use waterways in towns and cities throughout Britain. The animals have now been seen in 100 urban centres, including cities that are, on the face of it, some of Britain's least wildlife-friendly and most industrialised places, such as Birmingham, Leeds, Bristol, Newcastle upon Tyne, Glasgow and Cardiff.

There are even more surprises. Otters in Tavistock, sure, otters in Shrewsbury, OK, but otters in Stoke-on-Trent? In Sunderland? Bournemouth? Wolverhampton? And they're not all just passing through. The animals are living and breeding in urban watercourses in at least 13 towns and cities, including Newcastle.

Conservationists are delighted – and have suggested that future building projects should incorporate otter-friendly features, such as resting ledges under bridge arches.

Three developments seem to have coincided to bring the otter to town. The first is the recovery of the otter population itself, after the terrible crash in the late 1950s. From being a common animal, the otter declined dramatically from about 1957 onwards, largely because of the use of organochlorine pesticides in agriculture, which washed into rivers and built up in the animals' tissues. By the 1970s otters had been wiped out in most of lowland England.

But the pesticides were eventually banned, and from its strongholds in the West Country and Wales the otter has made a startling comeback, especially over the last decade, returning to many rivers where it was once familiar.

The move into towns is an extension of this, as an expanding population increases its range, and it is occurring rapidly: a survey four years ago found only 28 urban centres where otters could be seen within the town or city boundary.

The second reason for the otter's return is the national clean-up of waterways. Britain's rivers and canals are purer than at any time since the dawn of the Industrial Revolution, according to the Environment Agency, reflecting the £30bn that has been spent on improving sewage treatment since the privatisation of water in 1989.

About 95 per cent of them are now in the "good" or "fair" categories, which means they can support substantial aquatic life; last year a salmon was caught in the Mersey, the first for 130 years.

The third factor is probably the urban regeneration movement of the last two decades, which has led to greater appreciation of water features in city centres. As a result, river banks and old canals have been spruced up. They are no longer merely graveyards for shopping trolleys but attractive aspects of urban developments in such places as Birmingham, Leeds and Manchester (though the last is still devoid of otters).

But problems remain. The urban otter faces all the hazards of the built environment, including lack of secure places and road deaths. It is this that has led the Wildlife Trusts partnership to call for local planning authorities and developers to consider the needs of the otter when building along urban waterways.

Otters require suitable breeding habitat and resting sites – normally sheltered vegetation and a gently sloping riverbank. A number of mitigating features could be brought in, the trusts say, including ledges under bridge arches across which otters could travel, stationary or floating resting platforms, underpasses combined with otter fencing alongside road edges, and a drop-weir scheme whereby boulders or steps guide the otter down weirs.

"The recovery of the otter is the most exciting wildlife success story of the last decade," Simon Lyster, director-general of the Wildlife Trusts, said. "Watching otters at play has been largely restricted to remote areas of the countryside, but now otters seem set to become a part of urban wildlife too.

"Important wildlife habitat can exist in urban areas and people are now more likely than ever to be able to catch a glimpse of one of the UK's most charismatic creatures."

Secret lurking in city's dark arches

The dark Arches area in Leeds city centre is the last place you might expect to find otters, even though the river Aire flows through it.

It is next to the main railway station and a shopping mall, with a new office block and a car park on one side of the river, old warehouses on the other and steep industrial banking all the way along.

But last week a car park security guard watching his closed-circuit television screen saw, to his surprise, a long dark form emerge from the river in the early hours, cross the car park and return to the water.

Brian Lavelle, otters and rivers officer for the Yorkshire Wildlife Trust, checked the CCTV footage on Friday night and identified it as an otter. To make doubly sure, at the weekend he went down to the river bank and found two spraints ­ otter droppings ­ and the remains of a large fish, probably a perch, that the otter had caught and eaten.

Otters have been moving closer to Leeds over the past four years and are now right at the heart of the city.

"It's very exciting," Mr Lavelle said. "But what concerns us now is that the presence of otters should be taken into account in city centre development.

"For example, there are a few patches of scrub and brambles in the area which are likely to be 'tidied up' in future, but are in fact ideal for otters to lie up in. They should be left alone, with ... a sign to explain to people what their worth is.

"Development land is worth so much money that it's hard for planners to take anything else into account, but we're trying to get across ... that otters should be a great asset."