On my lake-side walk with Ben Casey, Project Officer for the Wildlife Trust BCN (Bedfordshire, Cambridgeshire, and Northamptonshire) at the Nene Wetlands, he suggests we veer off the path. In muddy late January, we scramble down a brambly bank to get to a large tree that has recently fallen. But this hadn’t succumbed rot or bad weather – it was felled by beavers.
I’m back at the Wildlife Trust site in Northamptonshire, next door to the Rushden Lakes shopping centre, one year on from its historical reintroduction of beavers to the site, to see what impact they have had. The family of five, transferred from a site in Scotland, have since added to their brood. Mum and Dad, Boudica and Alan, added new kits Holly and Willow back in September – the first baby beavers born in this part of England for over 400 years. They have since been exploring their new home, Delta pit, one of the larger lakes at the wetlands, but separated by metal fencing to keep the beavers in.
Ben is keen to show me just “how much they have achieved”.
As we emerge, slightly scratched, at the water’s edge, what we’re looking at is immediately clear: the red raw wooden trunk gnawed into a clear conical shape. On the far shore is a much bigger tree, also felled. They do this to manage their food source. Beavers strip the tree bark to eat the softer wood underneath. They fell the tree so that they have the entire length to nibble on, not just the part at ground height – and they fell it purposefully to fall into the water, where they can access it most easily; the water also helps to soften the wood, making it easier to eat. The entire watery habitat becomes the beaver’s walk-in (well, swim-in) larder. Other Eurasian beavers (Boudica and Alan are ancestors of Britain’s native species – not the North American kind) have been known to nibble on 200 different species of plants, Ben tells me, but “Willow, Poplar and Aspen are top of the list”.
Further down the lake, we wade out to a clearing in a reed bed. A large willow tree has been gnawed down to stumps, and narrow cleared water channels radiate out from it through the reeds. The beavers build the canals to be free from predators, Ben tells me – although reaching an adult weight of 35kg, they no longer have any natural predators. Even so, they go to great lengths to keep their favourite canalised paths in place, packing the sides with reeds, twigs and mud – “it's purpose-built and maintained”, says Ben.
Unlike the felled tree from earlier, the large Willow tree stump amongst the reeds isn’t dead. More accurately, it has been “pollarded” by the beavers. According to The Royal Horticultural Society, pollarding is “a pruning technique that maintains height and encourages fresh growth”. And just as it is for gardeners and groundskeepers, so it is for the beavers. While they do fell some trees to add to their larder, and for building material (including dams – we’ll get to those later), they are more interested in sustainably managing their food sources. By pollarding (ie. pruning) the willow they encourage fresh, tasty shoots to reappear in spring, and shoots at a manageable level close to the water.
Willow trees and reed beds also compete for space in wetlands, and nature reserves like this require regular clearance from paid employees like Ben or teams of volunteers. “There was a project around about 10 years ago or so where we had to clear a number of large willow because the reed bed was suffering”, informs Ben. “Eventually the willow will succeed and outcompete the reeds and the reedbed will dry up, and we won't have that habitat anymore… but now the beavers have come in, they do it all for us”.
Another unique aspect of beaver engineering is the lodges they construct to sleep in. Ahead of their arrival a year ago, the licence agreement from Natural England required Ben and his team to construct a ready-made lodge for the beavers to help them settle in. “It was me and my colleague Gav who put it together”, laughs Ben. “We tried our best – it was like old school den-building really. We were just piling sticks on top of each other and trying to make it look as amenable as possible”. They even scattered some parsnips, apples and carrots around as a welcome snack. For the first couple of nights, Ben and his team pored over the den’s nighttime camera footage – from camera traps supplied by Graf UK. “But very quickly, they moved on”, laughs Ben. A beaver’s gotta build.
Rather than build one lodge, the beavers now have about three dotted around the lake, which they prefer to use at different times of the year. The common denominator is that the entrance hole is always below water. And rather than a mini wooden chalet standing proudly above water, the wood is more of a roof ontop of an excavated burrow. “They burrow into a bank side, underneath the water level, and then up towards the bank and cap the top off with materials”, Ben tells me. If a wolf, bear, or lynx came sniffing around – or, let’s face it, a human – they could escape, unseen, through the hole to the water below.
Beavers are known to “size” the felled trunks into more manageable logs.
In just one year, Boudica and her growing army have felled and pollarded the trees they need for food (but left most in place), built three houses and designed and maintained several canals. So, what’s left on the to-do list? Two very big ones: 1. Build a dam. Their natural instinct is to seek out running water and dam it, to expand their shallow watery territory. But to do that requires achieving Number 2. Escape the fenced metal confines of Delta pit.
Shortly after moving into their new Northamptonshire home in February 2025, Defra changed the rules. Now wild beaver releases, without the need for metal fencing, are allowed – if they meet a (long list of) criteria. So why are the fences at Rushden Lakes still here? And what benefits could Boudica et Al bring is that they were set free into the neighbouring River Nene, and beyond? That will be the topic for our next blog and podcast 21…
