KNOWLEDGE BASE

This study in Washington, USA, found that beaver dams significantly increased the quantity and diversity of amphibian species. The dams increased the length of time for which open water was accessible for amphibians, so beavers particularly benefitted slow-developing species like red-legged frogs and northwestern salamanders. Many areas face decreasing water levels due to climate change: these findings suggest that beaver restoration can help ecosystems to adapt to such changes.

This study looked at how landscape structure and population density affected the aggressive behaviours of both Eurasian and North American beavers. It looked at tail scars from over 1,000 beavers. In interconnected landscapes such as lakes and rivers, aggression increased with population density in North American beavers. The relationship was more complex for Eurasian beavers. In more isolated habitats (ponds), population density had little impact on aggression.

This study examined how beavers affect aquatic invertebrates in lowland streams in Poland. Comparing two forest streams - one with beaver ponds and one without beavers - it showed that dissolved oxygen levels decreased in beaver ponds. This led to changes in invertebrate communities, including insects. Please note, this resource is not open-access.

This study shows that wolves impact ecosystems by preying on beavers, preventing them from engineering their ecosystems in specific places. When beavers disperse, they usually do so alone. So if they get eaten by a wolf, their pond will not be maintained. This then limits all of the impacts that beaver activities can have, such as that on water storage, sometimes for several years. Predators therefore shape how beavers' impacts are distributed across the landscape, although they don't hunt enough to suppress the total number of beavers in this area.

The researchers held interviews with individuals who reported conflicts with beavers (Castor fiber) during the River Otter Beaver Trial and identified five key themes that should be considered when engaging with people that could be affected by reintroduction conflicts: (1) proactive engagement or a fast response; (2) appropriate communication; (3) shared decision-making; (4) sense that humans are responsible for conflicts with reintroduced species; (5) a need for certainty.
The study concludes that engagement with affected individuals will likely be improved, with reduced conflict potential, where these themes are addressed.