Eager beavers - managing wetlands in Derbyshire the natural way

They’re nature’s original engineers. But how will reintroducing beavers help to manage flood and drought risk and support healthier wetlands in Derbyshire? Kate Lemon reports

Two years ago, on a beautiful sunny autumn day, Derbyshire Wildlife Trust (DWT) released a pair of beavers into Willington Wetlands Nature Reserve in the Trent Valley, south of Derby.

We watched with mixed feelings – excitement, relief, trepidation and awe – as the two large animals waddled calmly out of their travel crates and slid into the water, ignoring the rest of us standing on the riverbank. We watched as they dived and rolled, then vanished into the reedbed to enjoy a snack.

Beavers last roamed Derbyshire more than 800 years ago. They once thrived in England, Wales and Scotland, though not in Ireland. We prized them for their fur, meat and castoreum, a scented secretion used in perfumes, food and medicine. So much so that by the 16^th century, Britain had hunted its beavers to extinction.

Derbyshire is not the first English county to reintroduce beavers. England released record numbers of these loveable rodents in 2020 and 2021. But for DWT, the release ended two years of delays, spiralling costs and lockdown-related supply-chain problems, as we grappled with the rules and regulations.

Why did we bring beavers back to Derbyshire? We’d gathered overwhelming evidence that beavers offer the nature-based solution to managing and restoring our wetlands. And many other conservation groups agree. But not everyone feels having more beavers is positive. Some farming groups and others are wary.

We have evidence from Europe that – as always when you reintroduce wild species – new populations of beavers can come into conflict with people. We must address concerns that beaver dams cause floods or damage crops and trees. We must consider the unwanted impacts before reintroducing species that have been absent for so long.

Beavers are vegan. Yet many people think they eat fish or worry that their presence damages piscine populations. The Angling Trust opposes bringing back beavers, arguing that dams prevent fish migration. But surely England’s 20,000 manmade weirs and dams create far more – and more problematic – barriers?

Nature’s water managers

Beavers famously build dams. These permeable, impermanent structures slow water’s flow and create quiet pools that offer breeding or nursery areas for fish and keep water levels constant during droughts.

In tributaries, these dams slow flow speeds, encouraging deposition of silt before the water reaches main rivers, where it can leave less space for water. This is becoming a major problem in the UK when heavy seasonal rainfall creates flash floods and repeat inundations of homes and businesses as rivers reach capacity.

But after DWT released its beavers, a local NFU member contacted us, worried that the nature reserve faced mass destruction of trees and irreparable damage to woodland as “the beavers would eat all the trees”.

We tried to explain that beavers prefer wetland trees – aspen, willow and alder – and fell larger trees only to reach younger, more tender foliage at the top. In theory an adult beaver could fell a foot-wide tree in a night but our animals prefer to graze the smaller, easier-to-reach and more nutritious trees and saplings that dot the reedbed at Willington.

We can also take steps to protect mature trees from beaver felling; coating them with a nasty-tasting mix of tar and sand or wrapping them in beaver-proof fencing.

The wetland tree species beavers favour have evolved to regenerate quickly, a feature that many land managers know to their cost. But rapid regrowth aids carbon capture. Trees sequester most carbon in their first 75 years.

The Willington beavers have returned to where they first coppiced willow on the reserve, farming the regrowth and rotating their food sources.

The law has changed since, but when we released our beavers England didn’t recognise beavers as a native species. We had to fence Willington Wetlands to prevent our beavers colonising new areas.

DWT has owned the site since 2005. Selfishly, we were happy to keep the beavers on the nature reserve, where volunteers have battled for many thousands of hours yet still failed to stop willows’ relentless spread through our wetland.

We wanted the beavers to do their worst to the willows and bring diversity to the age and structure of light-blocking, thirsty saplings that have invaded a reedbed, home to water rail, bittern, reed bunting and water vole.

Building the numbers

People always ask us how many beavers we were allowed to release onto our 46 ha site, and how many we expect to see during our five-year possession licence from Natural England.

Based on advice from beaver-reintroduction expert Derek Gow and The Beaver Trust’s Roisin Campbell-Palmer, we were licensed to have two family groups and up to six animals per family.

Because trapping beavers can be slow, difficult and unpredictable we received two adult pairs, ten days apart, in separate areas of the reserve. This reduced the risk of conflict, allowing the two pairs to bond and establish territories.

Our licence required us to fence the site to prevent escapes. We have a 3km boundary. Beaver fencing must be robust. It is not cheap. Typically it needs a 10cm x 10cm mesh, 1.2m high and with a 40cm overhang as beavers can climb. Ideally you bury beaver fences up to 80cm deep, with a 40-80cm skirt inside the enclosure, pegged to the ground.

As of October, England classes beavers as a native species that is legally protected. But England does not yet approve wild releases, so all new populations must be enclosed, for now. Scotland approved wild releases in November 2021.

Many hope England will take a lead from Scotland, which has developed a beaver strategy for 2022-2045, having consulted more than 50 stakeholder bodies. It aims to expand Scotland’s beaver population to new catchments, with appropriate management.

Critically, the Scottish strategy aims to empower and support communities to maximise beavers’ environmental and wider benefits and to minimise any negative impacts.

Building knowledge

Releasing our beavers starts a long journey. DWT aims to share everything it has learned about reintroducing beavers and its impacts. We prepared the site having surveyed its species and habitats, using appropriate and recognised methodologies.

We will repeat these surveys annually to build solid evidence about the impacts – for better or worse – of reintroducing beavers. We monitor and track the animals continuously, using several methods – trail-camera footage, monthly aerial drone flights, annual electrofishing in the brook that crosses the site and fixed-point photography.

We worked with specialist contractor ACE Nature to develop an app to record and process our many hours of footage. ACE Nature has built a bespoke, interactive website to host the data. This is constantly being updated. We’ve created films, reels – even an immersive virtual-reality headset experience.

Next, we hope to start live streaming from the site. The footage will reveal the secret lives of our beavers – and those of many more incredible wildlife species that live in our nature reserve.

For England and Wales to continue to release beavers, we need many more conversations about whether it’s the right thing to do and about its wider, long-term impacts.

Many other countries in Europe have reintroduced beavers. This reflects the great affection that so people have for this large, charismatic, plant-eating rodent. A local hotelier from Knapdale in Scotland estimated in 2013 that a fifth of the guests who visited him that year came to see the reintroduced beavers.

Eco-tourism is delivering benefits to communities across the world. In rural Africa, communities are learning how to live alongside elephants and rhinos and earn an income from visitors wanting to see wildlife thriving in its natural environment. The UK’s growing numbers of rewilding projects can create spin-off incomes from walking safaris.

If we value our native species for their presence and create opportunities for people to view them in the wild, that demand can protect these species for the future and mitigate any negative effects that rewilding might have.

Rural diversification is not new to the custodians of our landscapes. Land owners and managers have always found new ways to create fresh income streams. Rewilding creates the chance to diversify from farming, shooting, fishing or hunting.

Did you know…

• An adult beaver can weigh up to 30kg and grow as large as a small Labrador – although most weigh around 20kg and are similar in size to a cocker spaniel
• Beavers are rodents: unlike mice or rats they are pregnant only once a year, giving birth to two to four kits per litter
• Beavers become sexually mature at around two years old and live for 12-14 years
• Beavers bond and stay with their mate for life
• Baby beavers, or kits, are typically born from April to July. Gestation takes three months
• Kits stay inside the den for at least four weeks, surviving on milk alone. Their parents bring plant material home to wean the kits onto solid food
• Tiny kits can struggle to learn how to dive, as they weigh very little and their waterproof fur is buoyant. The adults jump on them to help them to get fully underwater

Kate Lemon is Derbyshire Wildlife Trust landscape-recovery manager for the Trent and Erewash region, heading the regional operational team and securing funds for landscape-scale grazing and reintroducing beavers. This article first appeared in the May 2023 issue of The Environment magazine, published by CIWEM.