KNOWLEDGE BASE

In the context of widespread re-introduction efforts, this study tried to understand why North American beavers did not settle in certain areas of the USA. They found that typical cattle grazing disrupts the relationship between beavers and willow trees. By grazing, cattle make stretches of rivers unsuitable for beaver. Livestock management will have to change for successful beaver restoration in these areas. Please note, this resource is not open-access.

Published in 2016, at the time of writing the two wild populations of beavers in Scotland were present on a trial basis with the case of their full reintroduction is being considered by Scottish ministers. This review investigated the mechanisms by which beavers act as ecosystem engineers and discussed the possible impacts of beavers on the biodiversity of Scotland. The review states that a widespread positive influence on biodiversity would be expected, though detrimental impacts on certain woodland habitats and species of conservation importance is to be considered.

In this article, scientists investigated how wolf diets influence the distribution of parasites across an ecosystem. They examined wolf carcasses in Canada to understand their diet and the parasites they carry. Results showed that wolves consuming more beavers - not their prey of choice - had fewer parasites. This shows that food webs are not just affected by direct predation, but also by how predation enables (or not) certain parasites to reproduce.

In the USA, researchers studied the effects of radio transmitters on the survival of North American beavers. Both short-term and long-term survival and welfare wasn't affected by transmitter type and compared well to ear-tagged beavers. Transmitters caused greater winter weight loss, though, which might suggest a small impact on beaver survival and condition. On the whole, the authors say there is no reason not to continue using these tools for monitoring beavers.

Tail-mounted transmitters for tracking North American beavers were tried out for the first time in the northern USA. On average, the transmitters stayed on for only 133 days, with males and females showing similar retention times. Transmitters often detached due to beavers chewing antennas or damaging attachment points. This result is shorter than in warmer regions, and the authors suggested why this might be the case.