KNOWLEDGE BASE

North American beavers have severely impacted Patagonian ecosystems since their arrival in 1946. Eradicating them is now a priority, but predicting where they'll be is challenging. For recently-colonised sites, the 'bendiness' of the river is a good predictor of beavers' presence. This enables the use of satellite imagery for predicting the presence of beavers, which is useful for the remote areas of Patagonia.

This article reviewed the research on the engineering of beaver dams for both living species of beaver. It found that beaver dams reach lengths of 850 m and heights of up to 5.3 m. Beavers sometimes use rocks up to 30 cm in diameter as well as wood. The dams have a big impact on water flow, sediment processing, and flooding. The author suggested that beaver construction methods could inspire nature-based solutions for river restoration and flood control.

In Mongolia in 2015, extreme frosts caused beavers to become trapped in their lodge, preventing access to food. Local people released five trapped beavers, and all had freshly-gnawed tails. Without large terrestrial predators in the area, it's likely that the beavers gnawed their own tails. This text reported on this case and discussed the possible reasoning for it, suggesting it was likely a response to extreme stress.

This article reports on studies of Swedish beaver ponds, and the influence they had on the processing of dissolved organic material: that is, material which contains carbon. The age of the beaver pond was very important, with differences in processing between ponds and un-dammed streams disappearing as the pond ages. Therefore, beaver ponds temporarily increase organic matter in the water, diversifying the ways that carbon gets processed in the ecosystem.

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.