Latest beaver trial reports published

The four independent scientific studies describe the ecology of the beavers and their effects on the environment during a five-year trial reintroduction, which took place in Knapdale Forest near Lochgilphead and finished last May. Scottish Ministers will decide later this year whether to reintroduce beavers to Scotland, after considering the results of the Scottish Beaver Trial along with other beaver research. The trial was run by the Scottish Wildlife Trust and the Royal Zoological Society of Scotland, on land managed by Forestry Commission Scotland. During the trial the beavers were closely monitored by Scottish Natural Heritage (SNH) in partnership with a number of other independent organisations.

The beavers have established themselves at Knapdale and the population appeared to be stable up to the end of the trial, according to monitoring work carried out by the University of Oxford. However the number of beavers didn’t increase over the five years of the trial. Of the sixteen beavers released in May 2009, three died and five went missing. Fourteen beaver kits were born in the wild but many didn’t survive, with only one or two remaining. While the survival rates of the adult beavers that settled was considered relatively good, kit mortality was very high in some years - all of the kits from 2012 and 2013 were lost. The reason for this low rate of survival isn’t fully known but two of the kits were preyed on by other animals. At the end of the trial there were three groups of beavers at Knapdale and one single male beaver. They covered an area of 367 hectares, at a density of one beaver family per 5 km of water’s edge. Generally the beavers settled on the loch on which they were released. While all the beaver families built at least one permanent lodge, the building of dams and canals varied from family to family and year to year.

Researchers at the University of Stirling found that the beavers, surprisingly, have had little effect on rivers and streams in the trial area. Although they have explored many of the streams, nearly all of their activity has been concentrated around the lochs. It wasn’t clear if this was because the stream habitat was unsuitable or simply less attractive than the lochs. They have built some dams close to where streams flow in to or out of lochs but only where the water flow was slow. The study concluded that evidence from Knapdale suggests that few dams will be built on streams when there are a small number of beavers and they have easy access to lochs with wooded shores.

Another study shows that although beavers have had little effect on most lichen habitat at Knapdale, they have had an impact on lichens that grow on Atlantic hazelwoods. While the felling is very localised, affecting just over half of hazel trees within 60 m of lochs inhabited by beavers, there is concern that this may eventually cause a temporary or permanent loss of some the nationally and internationally important lichen habitat in the area. However the research showed that the majority of this habitat at Knapdale is unlikely to be affected. If beavers were permanently reintroduced to Scotland, they could have an impact on up to 27% of the Atlantic hazel habitat across the country. The study concluded that this would be a significant proportion, given the restricted global range of some lichens, but that longer term monitoring would be needed to fully assess the impact and that on lichens found on other trees favoured by beavers, such as aspen and those growing along rivers. Suitable management might be needed in the future if beavers were allowed to stay in Scotland.

Dragonflies were using the small clearings created by beavers felling trees, according to surveys of the hairy dragonfly and the beautiful demoiselle carried out by the British Dragonfly Society. They also found that dragonfly numbers may be falling at one loch that had changed substantially because of a beaver dam. But the researchers concluded that the five years of the trial was too short to fully evaluate the impact of the beavers.

Martin Gaywood, from SNH, who led the independent scientific monitoring of the trial said: “It’s essential that any species reintroduction project is properly managed and monitored. The independent monitoring of the Scottish Beaver Trial has helped us understand how beavers behave in a Scottish environment. We’ll be sending a report on the trial and a number of other beaver studies to the Scottish Government in late May. This means that their decision on the future of beavers in Scotland will be based on the best information available.”

ENDS

For media enquiries contact Nancy Fraser, SNH media & public relations officer on 0141 951 0809 / 0141 951 4488 or nancy.fraser@snh.gov.uk