Wild beavers set free in the Highlands as part of a pioneering reintroduction scheme are thriving and causing no harm to vulnerable wildlife in the area, the study by Scottish Government nature agency Scottish Natural Heritage (SNH) found.
The fourth annual report into the landmark Scottish Beaver Trial has found that the 17 Eurasian beavers living in Knapdale forest in Argyll are healthy and putting on weight.
Studies also show the rodents, which existed throughout Scotland until the 16th century, have not had an adverse effect on local otter populations.
Beavers were hunted to extinction in the UK because of demand for their fur and a glandular oil secreted from the base of their tail that was believed to possess medicinal properties.
Now the success of the groundbreaking scheme has sparked calls from conservationists to extend it and bring the animals back in other areas of Scotland.
Duncan Orr-Ewing, head of species and land management at RSPB Scotland, said: “Beavers are incredible mammals that have an important role to play in our countryside.
“Thanks to the excellent work of the Scottish Beaver Trial, we now have a comprehensive understanding of how beavers can thrive in Scottish ecosystems, and there is no reason why this cannot be repeated in other areas of Scotland.
“RSPB Scotland would like to play a role in bringing beavers back across Scotland, including on our reserves, and we are keen to work with other stakeholders to explore where and how this can be done.
“We urge the Scottish Government to make way for further projects to bring this remarkable species back to our countryside.”
The monitoring phase of the five-year project, run by the Scottish Wildlife Trust and Royal Zoological Society of Scotland, came to an end last month.
The report was carried out by SNH, which was brought in as an independent monitor for the trial.
The final results of the scheme are due in December, with the Scottish Government due to decide whether beavers have a future north of the Border by May next year.
A total of 16 beavers were released after the project kicked off in 2009, eight of which have survived. A further 14 young have been born in Argyll, though five of these have gone missing.
The remaining beavers make up four distinct family groups with a territory covering an area about the size of 120 football pitches.
“It is essential that any species reintroduction project includes a properly managed and monitored trial,” said Jenny Bryce, wildlife ecologist with SNH.
“This means that future decisions about extending the trial or moving to full-scale reintroduction are based on the best information available.
“The Knapdale beavers have been monitored since they were released and this work has been independently analysed.
“The monitoring shows us how the beavers are getting on at Knapdale and improves our understanding of how they behave in a Scottish environment.”