KNOWLEDGE BASE

The Beaver Salmonid Working Group considered various aspects of the relationship between beavers and salmonid fish in Scotland. This report describes literature reviews and site visits which contributed to their conclusions that a comprehensive management plan is needed before any formal reintroduction of beavers. This plan should involve stakeholder consultation, address concerns about fish passage, and consider the dynamic nature of beaver dams.

In this article, scientists investigated beaver aggression by looking at injuries on beaver pelts in the USA. Around one-third of beavers had injuries. Kits had fewer injuries than adults, as did beavers who live on smaller streams. There were no significant differences between sexes, suggesting that both sexes engage in territorial disputes.

This study presents the results of a study of the beavers present in Scotland's Tay catchment. None of the beavers screened carried diseases, thus presenting no health risks to local wildlife or people. The beaver populations are thriving and expanding, with some sites experiencing negative impacts on agriculture. Mitigation efforts were limited due to cost and effectiveness concerns; beaver removal was not an option. A need for advice amongst local land managers was identified.

At the end the 5-year Scottish Beaver Trial, a summary of mammal monitoring was published, to help understand the welfare of the released beavers and their impacts on other mammals in the area. The beaver population was stable but not increasing because a lot of kits had died. The beavers appeared to be behaving normally and had normal range sizes, albeit slightly on the small side. There were no negative impacts on local otter populations.

As part of the 5-year Scottish Beaver Trial, this paper summarises the impacts of beavers' reintroduction on two species of dragonfly. The report summarises the data gathered but the results are inconclusive. The author says that a 5-year trial was too short a timespan to produce clear results - one of the dragonfly species' larvae takes 3 years alone to develop!