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.

Eurasian beavers were extirpated (made locally extinct) in northern Russia but recolonised the area through introductions between the 1930s and 1950s. Both Eurasian and North American beavers now live in Finland and Russia. This text described the known distribution of both species across the region and discussed their genetic origins. The article included a map of where North American beavers can be found in the region near the Finnish border - here, the two species are competing for territory.

Wolves are natural predators of beavers in Eurasia and North America but much remains unknown about the two species' relationship. This article brought together evidence from both sides of the Atlantic. For wolves, beavers can be an easy and rewarding prey, but beavers do have their own protection mechanisms and wolves did not appear to be able to significantly reduce beaver numbers at a population level. The text highlighted that the wolf's expansion in Germany would bring them into increasing contact with beavers.