KNOWLEDGE BASE

This paper highlighted for the first time the use of beaver dam-and-pond complexes by freshwater mussels. The mussels are thought to spread by hitching a ride on different types of fish. The beaver ponds provide a refuge from strong stream currents, which mussels need to survive.

This article reviewed research on beaver canals, which had been less studied than beaver dams but also have significant environmental effects. Beavers build canals mainly to access resources and reduce predation risk. Canals vary widely in length (up to 500 metres!) but are often around 1 metre wide and half a metre deep. The canals change the hydrology of the river, create habitats, and benefit biodiversity. Figure 2 is an image showing the different types of beaver canal but this paper, overall, is a great introduction to the topic.

The Eurasian beaver population in Europe is rapidly growing due to reintroductions and natural expansion. Population-level data gets quickly outdated. Collected in 2019, this study estimates there are nearly 1,222,000 beavers in Europe.

When researchers try to predict where beavers may settle, they often relied on information from fully-established colonies, potentially misidentifying suitable sites for establishing a colony. In the USA, scientists analysed new beaver colony locations and found they preferred areas with low gradients, narrow channels, high canopy cover, and nearby low-lying areas. Adding artificial beaver structures can encourage beavers to settle in a specific place, too.

This article recounted the history of beavers in Italy. It says that humans likely played a significant role in making beavers extinct in Italy around the 16th and 17th century, but through altering habitat more than hunting. Beavers have likely never lived in southern Italy. The article includes maps of where beaver remains have been found in Italy and some images of beavers from medieval Italian texts.