CONSERVATIONISTS have become home builders to help an elusive lodger make a comeback.

The Environment Agency anti-pollution watchdog is installing pre-fab homes for otters, which are returning in numbers to the River Tees, but finding their natural habitat reduced by development.

Artificial holts, built from concrete blocks and plastic pipes, are being provided in secret locations around Teesside.

A lot of the otters' natural shelter has disappeared, leaving limited space for them to establish holts.

Katy Dickson, a conservation officer with the agency, said: "This is a great opportunity to help these wonderful creatures, and we are very grateful to the landowners who have been very pleased to cooperate with us in our aims.

"During flood defence works we have identified sites where we know otters can be found, but where natural cover is limited, and these are ideal locations for our artificial holts.

"There will be a number of other flood defence schemes happening in the agency's dales area, and we shall continue to look for further opportunities to help wildlife.

"We would also love to hear from any other landowners who would be willing to help."

An agency spokesman said: "Otters are reclusive animals and it is not possible to say exactly how many there are.

"We go by footprints and droppings because it is very rare to see one. And we can say there are otters throughout the middle and upper Tees. There are quite a lot of signs."

Otters were almost wiped out 20 years ago through pollution and the destruction of their natural habitat, but are returning to areas of the country after an absence of many years due to a £1.5m conservation scheme.

The Government has set a target of restoring otters to all the nation's rivers by the year 2010.