If any animal is the master of rewilding it must be the Eurasian beaver. Certainly, we humans could learn from how beavers improve the environment for the benefit of other species. Indeed the rangers at Sculthorpe Moor Nature Reserve are delighted and fascinated by the workings of the pair introduced to the reserve in April 2021.
“The male beaver came from Scotland and the female from Yorkshire,” explains David Ward, a Senior Ranger. “We had no idea if they would take to each other. So when the wildlife camera caught the pair preening each other within the first week of introduction, we were overjoyed.”
So successful was the pairing that in July 2022 two kits were spotted. The sex of these is still unknown. While the beavers are effectively captive within a 54-acre fenced area, they are treated as wild animals. However, the law requires them to be microchipped, so they will be caught and all will be revealed.
Busy as a beaver
The beaver enclosure with its network of dykes and drains brings to mind the phrase “busy as a beaver”. In 3 years the beavers have built a 6 foot tall igloo-like lodge, opened up ditches as watercourses, dammed streams creating small ponds and created a veritable animal Venice. Below ground they dig burrows which are believed to extend 4-5m into the bank. These provide underwater entrances to the lodge, chambers and access to waterways.
“If you see a beaver on land, it has a comical waddle,” says Ward. “They prefer to swim and are very agile in water. Hence they rarely venture more than a few metres away from a watercourse, so enabling a quick escape back to safety.”
Beavers are the second largest rodent in the world. They may grow to 1.3m in length, 0.5m in height and weigh up to 30kg. They construct dams from branches over 10 feet in length. And beavers are not only strong but very skilful. Ward described how the beavers use their front paws – somewhat akin to hands with their 5 digits – to pick up lumps of mud and pack around the cut branches and vegetation. Their composite building style is an animal form of wattle and daub.
Beaver myths and mitigation
Throughout history people have hunted beavers almost to extinction. For their meat, fur, and castoreum – a product derived from their castor sacs (scent glands) and used in perfume and food flavouring. The last record of a UK beaver was in Yorkshire in 1789. Their fate across Europe was a similar story until Sweden re-introduced them in the 1920’s. Then in 2009 Scotland embarked on a trial programme.
As with many re-introductions there was opposition. Claims that beavers would eat all the fish are unfounded – they are herbivores. That they would increase fish numbers. Beaver ponds may increase some species but their dams may also impede migrating fish.
As beavers are rodents, another worry was that they would breed like rats. Sexually active at around 20 months, a pair will only have between two to four kits a year. They also have a chromosome that inhibits interbreeding.
There were concerns that they would destroy all the trees. The beaver preference is for soft woods and saplings. But if these are not available, beavers will cut others and so mitigation measures may be required.
Farmers are concerned that beaver activity will impede farmland drainage. That their hidden burrowing will cause collapsing flood banks, increasing erosion and damage. That beavers will venture far and wide, causing damage to arable crops. Sculthorpe’s beavers are well fenced, but some concerns are valid. Hence a management framework exists to resolve conflicts between land owners, land managers and beaver wardens enabling harmonious co-existence.
Rewilding, beaver style
More beneficially, the beaver is sometimes described as an ecosystem engineer. Ward explained how dams effectively cleanse the water and improve floral diversity. “They filter out the rubbish and hold back the nutrient rich silt run-off from fields. This gives native meadow flowers, which prefer low nutrient soil, a better chance to thrive against invasive nettles and thistles”.
Coppicing of saplings along river banks is resulting in stronger, multi stemmed trees. This is believed to help promote roots which strengthen the banks. The reduction of the tree canopy improves plant diversity as more sunlight penetrates to the ground. This creation of glades and resultant rewilding attracts more insects and their predators, right up the food chain. Similarly, the creation of both dams and ponds offer habitats for fish, amphibians, mammals and insects.
The Hawk & Owl Trust regularly surveys the water voles, toads, frogs, damsel and dragon flies, butterflies, stickleback as well as bird life present in the reserve. “It’s really too early to say conclusively that the greater diversity of flora and fauna we see is largely due to the beaver’s rewilding efforts,” says Ward. “But we are very optimistic.”
The Beaver Trust, a charity devoted to restoring beavers, has collected evidence demonstrating the regenerative benefits that beavers offer the environment. Without doubt, humans could learn a lot from these masters of rewilding.
The Hawk & Owl Trust at Sculthorpe Moor Nature Reserve offer guided walks and private tours. The Trust welcomes volunteers to assist with surveys, fence checks, general maintenance and support.
