Conservationists are building a log-pile home for otters

They are building otter holts - or homes - on the Colin River to provide a resting and breeding place for the elusive creatures.

The last sighting of an otter in the park was in 2000.

But Maurice Turley, volunteers officer with the Colin Glen Trust, told BBC News Online that they have evidence that otters are beginning to use the river.

"We have seen their footprints and their spraints (faeces) down by the river," he said.

"When otters stop to catch fish, they often have a favourite rock which they like to sit on to eat. So we've found evidence there."

Mr Turley said a group of eight volunteers began work on a log-pile holt for the otters at the weekend.

"It is just at the side of the river and, when finished, it will have a couple of chambers and tunnels," he said.

The log pile is being constructed from wood gathered after a tree pinning exercise in the Colin forest where young saplings had to be thinned out because they were growing too close together.

However, the 200,000 people who visit Colin Glen every year will need to be persistent if they wish to see an otter which is essentially a nocturnal creature.

People who would like to see one need to look very early in the morning or just before dark.

"You'll see otters at Delamont or Strangford Lough. They can hunt over a range of 40 kms. We have nice, clean water and a good fish population which brings them up the river," Mr Turley said.

The otter is an important indicator of the health of rivers and wetlands and its gradual recovery in regions throughout the United Kingdom highlights the well being of the water environment and the animals it supports.

The British government has set a target of restoring otters to all UK rivers by 2010.