Beavers have become synonymous with the rewilding movement in the UK. Their widely publicised return is likely to have a profound impact on the landscape, say the authors of a study
The Eurasian beaver, once a common sight across Europe, had disappeared almost entirely by the end of the 16th century thanks to hunting and river modification for agriculture and engineering.
But beavers are making a comeback across the UK and several other countries. They have already been released into the wild in Scotland and within enclosed river sections in England. Now expanding the wild release of beavers across England is on the cards.
Ecosystem recovery, increased biodiversity, flood protection and improved water quality are some of the upsides of having beavers around. But reintroducing wild animals to the landscape is always going to involve trial and error, and it’s vital to understand the possible consequences – both good and bad.
The beaver is a gifted environmental engineer, able to create its own ecological niche – matching itself perfectly to its environment – by building dams. These dams are made from materials the beaver can carry or float – typically wood, stones and mud, but also fence posts, crops from nearby fields, satellite dishes and old kids’ toys.
The dam creates a peaceful, watery home for beaver families to sleep, eat and avoid predators. And the effects of dam building ripple outwards, with the potential to transform entire ecosystems.
Our review of beaver impacts considers evidence from across Europe and North America, where wild beaver populations have been expanding since around the 1950s.
Water
There is clear evidence that beaver dams increase water storage in river landscapes through creating more ponds and wetlands, as well as raising groundwater levels. This could help rivers – and their inhabitants – handle ever more common weather extremes like floods and droughts.
Beavers are gifted environmental engineers, using trees to make dams. Image: Fietzfotos
If you observe beaver dams in the wild, water often comes very close to the top of their dams, suggesting they might not be much help in a flood. Nonetheless, some studies are finding that beaver dams can reduce flood peaks, likely because they divert water onto floodplains and slow downstream flow. However, we don’t know whether beaver dams reliably reduce floods of different sizes, and it would be unwise to assume they’re always capable of protecting downstream structures.
The good news is that it seems all the extra water dams store could help supplement rivers during dry periods and act as critical refuges for fish, amphibians, insects and birds during droughts.
Learn More: https://www.positive.news/environment/rewilding-beavers-are-back-heres-what-this-might-mean/