Beavers. Biodiversity’s secret weapon?

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Beavers. Biodiversity’s secret weapon?

I’m often asked, ‘why do we need to conserve or restore certain species or habitats’, ‘what do we need that species for?’, ‘What is the point of them?’. When I get asked this question for beavers, the answer is easy – they are keystone species and ecosystem engineers, vital to the health of our wetlands. 

Keystone species are critical to the function of an ecosystem. Quite simply, their presence enables the survival of other species within the system. Without them, an ecosystem becomes depleted and vulnerable to change. In architecture, a keystone is a wedge-shaped stone located in the apex of a masonry arch. It is the final piece placed during construction, and locks and stabilises all the stones in position. This allows the arch to bear weight. When applied to a keystone species – the ‘stones’ or animals within an ecosystem can still remain without the keystone, but they are vulnerable to ‘bearing any weight’ or in the case of an ecosystem are vulnerable to change. The keystone species holds all the other species together within an ecosystem, and allows it to function and be resilient to change –  notably, climate change. 

In the UK, we have many ecosystems where keystone species are depleted or absent entirely. This is affecting our view of what our countryside should look like, and how habitats and species should be functioning. It’s difficult to appreciate what has been lost, and how this is impacting our biodiversity as a result. But the symptom of missing keystones lies within the stories of nature decline in the UK. The return of beavers brings hope to landscape nature recovery in the UK! (NB: not all heroes wear capes…)

Beavers are a keystone species and ecosystem engineers. This is because their presence within an ecosystem causes a direct change in its environment. River, stream and lake habitats are transformed to a varied habitat when beavers are present. If you have ever seen an area where beavers have been introduced, you will see how depleted many of our wetlands are without them. Being an ecosystem engineer means that you have to create some ‘damage’. Beavers fell trees, build dams, dig canals, and essentially create a bit of a mess. But, this messiness creates variety, and variety is what increases biodiversity and resilience. 

Beaver pond varied water depths
Credit: James Wallace

Trees are felled, but are kept in the ecosystem as deadwood within dams and lodges, creating habitat for insects, which provide food for many species of wildlife including reptiles, amphibians, bats and birds. Many of the felled trees regrow, creating new shoots for other species to feed on. The felled trees create open areas, where meadows and grasslands flourish supporting wild flowers, bees, more insects, and water voles. Canals are dug by beavers to move woody material around, which create wetland areas within the river corridor where many more species thrive. Pools are created behind dams which support fish species, frog spawn and dragonflies. Bats will often forage over these pools, dipping towards the clear water to feed on the many insects that it supports. It also supports bird species, including foraging kingfishers. Where once there was a narrow river or stream surrounded by dense scrub or tree cover, we now have a varied wetland corridor where many more species flourish. 

Beavers restore ecosystems, and more biodiversity means more resilience to storms and droughts, as well as other pressures on our habitats. My research of beaver enclosures in the UK has recorded this increase in biodiversity within bats, mosses and aquatic insects, often within two years of beaver reintroduction. And – (crucially!) beavers create these transformations for free, without the need for intensive management by people. 

So, in answer to the question ‘why do we need beavers?’ – the answer is clear. Our rivers and wetland ecosystems need the variety that beavers create. Without them, we have one or two types of habitat. But with them? We have many more habitats, which support many more species. In a time when we are facing an ecological crisis, beavers are a ray of hope to restore some of the ecosystems that we have lost and start landscape scale nature recovery across the whole of the UK. The presence of this one species creates habitat that can support hundreds more species, from plants and mosses, to insects, bats, birds, reptiles, amphibians and mammals, and restores our freshwater habitats to how they should function and thrive. We need beavers to return to many of our wetland areas to kick start the recovery of wildlife and biodiversity. 

Contact us for support at and visit for more information and to arrange a trip to the Cornwall Beaver Project.

Sara King Sara King

Sara is an ecologist, specialising in biodiversity monitoring. She has been monitoring beaver sites in England and Wales for five years, focused on using technology to survey aquatic invertebrates, bats and mosses. She is currently writing a research paper into the benefits of beavers for biodiversity. 

#beavers #beaverbelievers #beavolution

© Sara King 2020

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