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Eurasion Beaver - A keystone species

One Voice for Animals UK Guest Blog by Rewildingbritain

© Peter Cairns/

Eurasian Beaver (Castor Fiber) - Natures busy aquatic architect is a formidable tree feller, river changer and wetland creator.

How it shapes the landscape

The beaver is a keystone species and one of nature’s most awesome ecological engineers. Through the building of dams, the digging of canals, and the creation of dead wood, beavers create and maintain habitats where an abundance and diversity of life can flourish. Dams prevent soil eroded from fields from being lost to the sea. Carbon and nutrients are trapped, improving water quality downstream. The flow of water is slowed, helping to ameliorate flooding.

Beavers are vegan and don’t eat fish or other animals. Studies have shown that young salmon grow faster and are in better condition in areas where beavers live. A host of other creatures benefit from their presence including insect, amphibian, bird, and mammal species

Where it likes to be

Beavers require freshwater habitat with lots of woody vegetation. They’ll build dams to create ponds where they can construct their lodges and stay safe. They are herbivores, feeding on grasses and trees. They’ll forage the land around their homes, felling trees and moving branches and twigs into the water

How much space they need

Beavers need a minimum of a couple of hectares, including freshwater habitat and ample supply of trees and shrubs. Final territory size depends on food availability

Background Story

Europe’s largest rodent was hunted to extinction in the UK for its fur and a natural secretion called castoreum, which was used for both perfumes and medicine. Similar declines followed in mainland Europe, with the population plummeting to almost 1000 across the continent. Beavers have since been successfully reintroduced and protected in many countries, including Scotland and England.

Special Power
Beavers create habitats that allow hundreds of other species to return and flourish. They slow the flow of rivers, reducing the danger of flooding

Can we have them in Britain?

Wild beavers, and those in captive release schemes, can be found across Britain. In Scotland beavers have been declared a native species and they enjoy a European Protected Species status. The largest wild population lives in the Tay catchment, and has spread into the River Forth catchment. In England the government has launched a Consultation on more reintroductions to the wild after a successful trial in Devon.

Beavers help mitigate flooding and provide habitats © Cavan Images

1. REDUCE FLOODING The most obvious benefit we get is the dams and networks of watercourses that they create, which can store vast amounts of water. They build dams to make the water around the entrance of their lodge deep enough to access safely, and also dig out new channels to serve as a safe way to explore their local area. Not only can this network of ponds and small ​‘canals’ hold significant amounts of water, these intricate watercourses also push water out slowly into the surrounding soils, creating absorbent wetland habitats. With many of Britain’s surface and river flooding events caused by too much rain falling too quickly, which then rapidly moves through our degraded landscapes, beaver engineering works can be a lifeline for communities living downstream. Findings from the trial in Devon show that the beavers reduced flood flows by up to 60%, even when the weather had been very wet. By holding back the water in newly created wetlands and pools, water trickles out of the system at a much slower rate, which reduces the chances of flash flooding after storm events. Between 2015 and 2021 the UK government spent £2.6 billion on flood defences, with this expenditure planned to double over the six subsequent years. Beavers could help us manage flooding at a fraction of the cost.

“Rewilding is a crucial tool in the toolbox for tackling the nature and climate emergencies. Beavers can do much of that rewilding completely free of charge in river and wetland environments.”

Professor Alastair Driver Director, Rewilding Britain

2. LESSEN THE IMPACT OF DROUGHT The flip side of the coin is that beaver ponds and canals can also help us mitigate the effects of drought. Here in Britain, ​‘drought’ is brought on by below average rainfall, which fails to replenish our water reserves over several months – and can have serious financial impacts on farmers in particular, whose crops and livestock are dependent on water to survive. What’s so unique about beaver-shaped wetlands is that they continue to release water slowly into surrounding soils and downstream during dry periods, helping to keep water flowing. The study of a Canadian river catchment found that, where beavers were active, there was 60% more open water present during drought than there had been prior to the beavers’ return. Early research on British beavers indicates similar benefits.

3. ENGINEER A MOSAIC OF HABITATS In a few short years at the Devon Beaver Trial activity by beavers had already created a mix of wetlands, ponds, deadwood, open grassland, scrub and trees, plus areas of sphagnum moss – and similar results have been found elsewhere. This mosaic of habitats in turn supports a wealth of species, including dragonflies, butterflies, brown trout, salmon, as well as bat, bird, reptile and amphibian species. It’s not just that overall numbers increase; so does the variety and the rarity. Beavers are territorial, staying close to their ponds and canals to gnaw on plants (contrary to popular belief, they don’t eat fish), meaning that these areas evolve differently from the areas they leave alone – all contributing to the rich diversity of their landscape. Favouring trees such as willow and aspen, their ​‘coppicing’ effect on these species alters light levels in woodland and scrub, and other trees tend to increase as a result. The fallen trees create open meadow habitats, whilst new branches grow out of the coppiced tree creating new feeding opportunities for a range of wildlife.

4. IMPROVE WATER QUALITY As well as changing how water moves through our landscape, beavers also improve the quality of water. Several American and British studies have found that beaver ponds reduce nitrogen pollution in watercourses – with many of the nitrates digested by the bacteria in the pond, and others trapped by the sediments. In Devon, beaver ponds have been shown to prevent sediments and pollutants from flowing downstream. Water entering them contained around 150mg of sediments, water leaving contained only 40g. In Britain, where only 14% of UK rivers are in good ecological condition and around 70% of nitrate pollution in our rivers comes from agricultural run-off, beaver activity is key to limiting how much of this pollution remains in our waterways.


· Keystone Species

· Europe's largest rodent

· Extraordinary ecosystem engineer, creating habitat for a multitude of wildlife

· Hunted to extinction around 400 years ago, now successfully reintroduced at locations across the UK.

· Dam building helps ​‘slow the flow’, reducing flooding and improving


  • Wild Ken Hill - Norfolk

  • Bamff Estate - Scotland

  • Upcott Grange Farm - Devon

  • Knepp Castle Estate - Sussex

  • Lowther Estate - Lake District


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