If you follow any wildlife or nature accounts on social media, then you may have noticed an influx of posts about beavers over the last month. So, what is going on and why are people excited? In a sentence: plans are being made to reintroduce beavers into the wild in the UK and grant them legal protection as a native species. But what makes this so great, beyond the obvious excitement of regaining a species we hunted to extinction?
The Eurasian beaver (Castor fiber) is the second largest rodent in the world after capybara and was once widespread across Europe, including the UK. However, they were heavily hunted for their soft fur, meat, and a secretion called castoreum (historically used in “medicines” and as a food additive). This persistent persecution drove beavers to extinction in the UK by the 16th century and restricted their population to a few sites in France, Germany, and Norway. However, hunting control and reintroduction programs have benefited the European population with beavers becoming ever more widespread and reaching numbers of around 1.2 million. Reintroduction into the UK has been slow, often with misconceptions of them eating fish (they are fully vegetarian), causing a conflict of interest. However, the beaver became the first mammal officially reintroduced into the UK. This occurred in Scotland, and they were granted status as a European Protected Species by the Scottish Government in 2019. Following reintroduction trials and the success of the Cornwall beaver project, they are being granted legal protection in England, making it an offence to deliberately capture, kill, disturb, or injure them. This is fantastic, not only because it is great to see the return of a native species, especially one as charismatic as the beaver, but also because of the host of benefits that they can provide.
Beavers are known as a keystone species and ecosystem engineers due to the profound impact that their presence and behaviour has on the ecology and biodiversity of the surrounding area. So much so that they have been proposed as a tool for implementing the EU water framework directive. Famously, beavers build dams, which have a range of ecological benefits. They retain ponds, causing nutrient build up and consequently creating a rich habitat that can support an entire food chain. These ponds have been shown to have increased invertebrate species diversity and even improve their resilience to drought . The abundance of insects in turn acts as an all you can eat buffet for other animals and greatly benefits fish by providing a constant supply of food. Alongside the ample dining prospects, the alteration to water flow also improves fish species diversity .
At the base of every ecosystem, you find the plants and beavers improve plant diversity both within aquatic habitats and in the surrounding area. A study found that after 12 years of beaver presence, both the plant species richness and the cumulative number of species recorded increased (figure 1) .
Beavers also coppice (cut back) trees, this activity has several benefits. Firstly, it provides a deadwood habitat, something that beetles, and other insects are particularly fond of, again increasing species richness and diversity . Secondly, it allows sunlight to reach vegetation that was previously shaded by trees, which results in an increase in plant diversity . This vegetation often takes the form of shrubs which provides cover and a habitat for insects, birds, bats, and amphibians.
It is difficult to get across just how much of an impact the presence of beavers can have on an ecosystem in a short article, but it is truly staggering. Their habitat engineering is remarkable, and it benefits every aspect of the ecosystem.
Climate and Humans
Engineering an ecosystem will also have an impact on the environment, whether it is done by humans or beavers. The construction of dams elevates water levels and can create a wetland habitat surrounding the pond/river. Not only does this further benefit wildlife, but wetland habitats are excellent at acting as carbon sinks (see my previous article ‘back the bogs’). Silt and sediment build-up occurs as a result of dam construction which further contributes to carbon storage.
Furthermore, as climate change continues to progress, droughts are becoming both more frequent and more intense. Due to the large quantity of water held by beaver created ponds and the increase in water content in the surrounding ground/soil, beavers can reduce the impacts of drought. This can also ensure a supply of water for human activities in times of water shortage. On the flipside, they also reduce flooding and mitigate the impacts of floods. The restriction of water flow speed as a result of dam construction reduces the likelihood of flooding downstream, whilst the increased water holding capacity of the surrounding area reduces the severity of any floods that do occur. Similar to the situation with droughts, this is beneficial both for the surrounding ecosystems and human activities, helping mitigate some of the impacts of climate change.
Beaver dams and the resulting ponds can also act as filters, removing pollutants from the water. This includes chemical pesticides containing nitrogen and phosphorus . Both components can cause problems downstream in the form of algal blooms and must be removed from drinking water sources. The surrounding wetlands also contribute to the removal of these often dangerous compounds, with the plants and algae providing an excellent filtration system. In fact, wetlands are often called the Earth's kidneys. One study that looked at the filtration activities of dams (using beavers in Devon) concluded that whilst further research is needed on the long-term impacts on nutrient cycling, beaver ponds have the potential to help diffuse agricultural pollution .
Beavers are incredible animals with an unmatchable ability to engineer an ecosystem. They have undoubtedly earned the title of a keystone species and it is fantastic news that they are gaining protection in England. I sincerely hope that more reintroduction projects will ensue, and the Cornwall beaver project can remove the fences. There are so many more levels to the benefits that they provide (from hydrological changes to reducing erosion) and I have only provided a small summary in the interest of not writing a thesis length article, but I will reference the cited sources below and link some cool websites if you want more information. Ultimately, they are not only great for improving biodiversity and ecological health, but they are also fantastic for mitigating effects of climate change and cleaning up our water systems.
Thanks for reading, I hope you enjoyed the article. As always, I welcome any feedback/questions and don’t forget to find me on social media.
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1 Brazier, R.E., Puttock, A., Graham, H.A., Auster, R.E., Davies, K.H. and Brown, C.M., 2021. Beaver: Nature's ecosystem engineers. Wiley Interdisciplinary Reviews: Water, 8(1), p.e1494.
2 Law, A., Gaywood, M.J., Jones, K.C., Ramsay, P. and Willby, N.J., 2017. Using ecosystem engineers as tools in habitat restoration and rewilding: beaver and wetlands. Science of the Total Environment, 605, pp.1021-1030.
3 Puttock, A., Graham, H.A., Carless, D. and Brazier, R.E., 2018. Sediment and nutrient storage in a beaver engineered wetland. Earth Surface Processes and Landforms, 43(11), pp.2358-2370.
A really cool interactive animation that shows how beavers change an ecosystem, really worth a look: http://highdesertmuseum.org/beaver-interactive/
The beaver trust is a great source of info on the history and benefits of beavers: https://beavertrust.org/index.php/beavers-create-healthy-rivers-for-wildlife-and-people/
News article on beavers gaining legal protection: https://www.theguardian.com/environment/2021/aug/25/beavers-to-make-cautious-return-to-england-with-legal-protection