KNOWLEDGE BASE

Beavers are famous for building dams, but often they live in a river without building a dam! This study looked at what factors influence where they build dams and how those dams affect water levels. They found river depth - particularly its lowest point during summer - was a strong influence on whether dams were built. Dams raised water levels upstream, often upwards of 40 cm. This information can be helpful for landscape planning in areas where flooding could cause conflict with, for example, agriculture.

This study examined how beaver dams affect the movement of Arctic grayling fish in the USA by monitoring the fish in real life. Fish had an 88% chance of making it past any given beaver dam, although at some specific dams the probability fell to 50%. They found that, in drier conditions, fish found it harder to get past dams. The results of this study could help inform management decisions: for example, when to breach a beaver dam to help fish get by.

The concept of "nature-based solutions" (NbS) is gaining popularity. However, it is battling with its own eurocentricity and there is confusion about its benefits for sustainability. This paper compares the varying definitions by groups like IUCN and the European Commission, and tries to create a common set of NbS principles. The paper cites the beaver trials in both England and Scotland as examples of NbS in action. Please note, this resource is not open-access.

Preliminary data from small rivers in a Russian nature reserve showed that Eurasian beaver activity had boosted biodiversity. The scientists meaured zooplankton, amphibians, and fish to determine this - beaver-made ponds increased the abundance of all three. However, the impacts on each group varied after the ponds aged, became abandoned, and eventually drained. Please note, this resource is not open-access.

This study compared the fatty acid composition of muscle tissues in pregnant beavers and their foetuses. Foetuses had higher levels of saturated and monounsaturated fatty acids but lower polyunsaturated fatty acids. The text discusses what role these different chemicals may have during the baby beavers' development.