Behind the secret birth of London's first baby beavers in 400 years – and what it means

Footage on hidden cameras confirmed what the team at Citizen Zoo had suspected: beavers had been born in London for the first time in 400 years. In the midst of “extreme excitement”, however, the small inner circle realised success depended on keeping the knowledge under wraps.

Since a historic family of wild beavers were introduced to London in September 2023, at the Paradise Fields reserve in west London, staff involved with the project hoped they would settle in enough to start mating.

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By late June, volunteers and members of the public brought piecemeal reports of small beavers accompanying the original contingent of mature mammals. Knowing beavers usually give birth in early June, the Ealing Beaver Project team set up cameras close to the lodge, where beavers give birth. It was mid-July before footage confirmed the birth of at least two “kits”.

“This was one of the major milestones we had in mind for the project. It shows they’re really thriving within that ecosystem,” said Ben Stockwell, a senior urban rewilding officer with Citizen Zoo, one of the organisations involved in bringing the beavers to London.

The births represented a landmark for rewilding in the capital, proof that nature can be brought back to the metropolis. It was the kind of news you can shout about. But in the tentative early days of life, when the kits needed to bed in, their existence was a secret. With a “reasonably high” mortality rate, Stockwell and his team did not want an influx of people looking for them.

A waiting game began as the excited staff left the baby beavers to their own devices. “We’re not interventionist. We are very happy to let things play out,” said Stockwell, adding emergency medical care would prompt action. “As far as we’re concerned, they are wild animals.”

So they waited. As the beavers grew, they began to eat vegetation – leaves, bark, and aquatic plants – and swim around. When the secret was ready to be revealed, it created national headlines. A triumphant team hailed it as proof that beavers, and nature more generally, could thrive alongside the residents of a bustling city.

Urban rewilding in the UK remains in its early days. But its proponents face a race against time to prove it can work. Two-thirds of the population is forecast to live in cities by 2050, while the threat of climate change brings storms, floods and heatwaves. Reintroducing nature to cities could mitigate the threat.

As the beavers create more wetland, reducing the risk of flooding, they are also creating the conditions for other species to thrive. Dragonflies, damselflies and the wetland specialist Daubenton’s Bat have all been spotted in greater quantities at Paradise Fields. Surveys of freshwater invertebrates confirmed the beavers’ dams were improving water quality. 

Water voles may soon be introduced to the beavers’ Ealing home. Once common in the UK, the tiny rodents saw their population decline by nearly 90% from 1989 to 1998. The culprit was the arrival of the invasive American mink.

“They’re predatory to an extreme, kill a lot of stuff at high speed,” said Joe Pecorelli, a project manager for Zoological Society of London (ZSL). “No matter which way you look at the evidence, mink are an incredibly destructive species that have been introduced and are now not just decimating water vole but also populations of certain ground-nesting water birds”

A scheme has been underway since 2022 to reverse the trend, with a survey revealing a handful of locations in London where water voles were hanging on. Key is culling mink to allow the voles to flourish, an effort led by the Waterlife Recovery Trust. Over the past 18 months, dozens of traps have been laid across north and south London.

Evidence shows that when mink are removed, water voles naturally come back in numbers, but sometimes need a little push. August 2024 saw 137 of the rodents reintroduced to Crane Park in south London’s Richmond. It’s currently too early to say how the London-wide efforts are going, said Pecorelli, but from next year more sites will be considered for active reintroduction.

“We are hoping that by next year there’s a real impact on the population of mink in and around the outskirts of London and we can evidence the recovery of water vole,” Pecorelli said.

Those working on rewilding projects face a challenge in proving their efforts are working. For ZSL’s work on water voles, this means help from the public, who have been asked to report sightings on a portal on ZSL’s website. It is key to understanding the success of the programme.

“The only way we can properly do that in an urban environment is by working with local volunteers through citizen science to gather the evidence,” said Pecorelli.

For Citizen Zoo, cash may make a difference. “We’re looking to roll out far more surveys going into the following year,” said Stockwell. “We’re currently looking for funding to cover robust surveys on site to go from anecdotal evidence into more robust data, to showcase how these changes are happening.”

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