Beavers used to be widespread across Britain and Europe, thriving along rivers, wetlands and meadows wherever there was enough water to shelter from predators, and enough vegetation to eat. But increasing demand for their fur and castoreum oil used in perfumes escalated in the 16th century and led to unsustainable levels of hunting, and to their decline across Europe and total extirpation from Britain. By the 18th century, beavers were completely absent from British waterways.
Floodwaters from rainstorms had no place on this industrialised landscape, and so rivers were dredged to funnel water downstream as quickly as possible. However, rivers that have been deepened and widened through dredging channel water rapidly at tremendous force downstream, since there are few obstacles to slow the water down. If this fast-flowing water hits a structure downstream, such as a culvert or bridge, the water can overtop the banks and cause flooding. We see examples of this on the Island during heavy rainfall events more often than we would like! (Image credit: Island Echo)
However, reintroducing beavers onto the landscape can help solve some of these issues. Beavers create ponds behind a network of dams that can store water and hold back flow during heavy rainfall events. Water flows slowly through these beaver establishments due to the friction of all the woody material and vegetation in the way, thus relieving the pressure on storm drains downstream. By slowing down and holding back the water, and storing it in ponds and wetlands, beavers give our downstream infrastructure more time to cope with rising runoff, thus mitigating the impact of flash flooding. Research from the Devon Beaver Trial support this, for more information click here.
Beaver dams can also improve water quality by helping to filter out pollutants from agricultural runoff. The dams can trap sediment and also nitrates and phosphorous washed off from farmers’ fields, which settle out from the slow-moving water in beaver ponds. This is great news for the Island, much of which is designated as a Nitrate Vulnerable Zone. The image shows water samples taken above and below beaver dams on the River Otter, Devon.
Beavers can greatly benefit the island’s biodiversity as well. By building dams and lodges, beavers can introduce lots of organic material and vegetation into their ponds, which is a great food source for macroinvertebrates. This then impacts up the food chain, with beaver ponds becoming great foraging areas for fish, amphibians, birds and bats, which in turn can provide more prey for predators such as otters and raptors. By creating more wetlands, and eating overshading trees, beavers can increase the amount of suitable bank area available for water voles too.
Due to all these benefits, Hampshire and Isle of Wight Wildlife Trust have announced plans to return the beaver to the Isle of Wight. A beaver reintroduction feasibility report was commissioned in 2020, with the Eastern Yar catchment found to be suitable. Newchurch Moors Nature Reserve was mentioned in particular as being a favourable release site, since there are already deep pools present left over from past peat extraction activities, which are surrounded by willow and alder dominated woodland. The Eastern Yar is considered to be an excellent location for beaver reintroduction, not just due to the quality of the habitat, but also since a large proportion of the river flows through land already owned by the Trust and its partners which is managed for conservation. Designated sites along the Eastern Yar including Alverstone Marshes and Brading Marshes SSSIs would benefit from the presence of beaver, and mitigation and landowner conflict in the catchment would be minimised on these sites already set aside for wildlife.
With the appointment of a Beaver Recovery Project Officer in August 2021, the Trust hopes to move to the next phases of making a beaver release a reality. Consultations will be carried out with stakeholders to develop a consensus on how to move forward, with feedback and mitigation strategies integrated into a Licence Application that will be submitted to Natural England within the next 18 months. And given a favourable outcome, beavers may soon be swimming along the Eastern Yar once more! For more details on this project please contact Izzie Tween at Izzie.tween@hiwwt.org.uk
