TO the joy of animal-lovers and the despair of landowners, Scotland's wild beavers are on the move.

A canoeist has uncovered the first evidence that the animals are migrating south from the Tay to the Loch Lomond & The Trossachs National Park. From there, they are likely to spread to large parts of Scotland.

A beaver was caught on film swimming in the River Leny near Callander earlier this month. That is the furthest south the animals have been spotted since they colonised the Tay and its tributaries in recent years.

About 100 beavers are thought to be living around Tayside, descendants of animals that either escaped from captivity or were illegally released. A threat to trap and remove them was lifted by the Scottish Government in March, pending a decision on whether to formally permit their reintroduction in 2015. But by then, beavers are likely to be impossible to eradicate.

Louise Ramsay, from the Scottish Wild Beaver Group, said: "It is very exciting to come across a wild beaver in a completely new area when they have been extinct for over 400 years."

Beavers used to be native to Scotland, but were hunted to extinction centuries ago for their furs, which are soft and waterproof, and for the oil they secrete. A Government-approved trial reintroduction is under way at Knapdale in Argyll.

The canoeist who filmed the beaver, Gavin Millar, was "completely overjoyed" at what he saw, adding: "I hope this will be the first of many sightings."

But landowners, fearful of damage to woodlands and flooding, are less delighted.

Drew McFarlane-Slack from Scottish Land & Estates, which represents 2500 landowners, said: "We are very concerned that beavers are spreading widely and in a completely uncontrolled and illegal way."

As a result of the new sighting, Scottish Natural Heritage is extending a survey of beavers to cover the Callander area.