FOR a number of years, the reintroduction of Beavers into the British countryside has been under active consideration, with several projects/trials underway or completed. Recently, these discussions have extended to Wharfedale. So, I thought it might be interesting to look, briefly, at some of the key issues.

These large rodents (up to 38kg) inhabit freshwater environments. They were native to Britain, but hunted to extinction a few hundred years ago. Often described as ‘ecosystem engineers’, they substantially alter their surrounding environment to suit their needs. They do this by: 1) building dams, so they can move around more easily, transport vegetation, and avoid predation in the deeper, slower water that is created; 2) excavating canals to have easier and safer access to nearby resources; 3) excavating burrows for habitation, although the construction of lodges is an alternative; and, 4) felling trees, for food and construction, using branches along with other vegetation, stones and mud for their dams:

Those in favour reintroduction argue that, on balance, and with some management, the changes they make dramatically improve waterways. That they transform them to a more natural state, with areas downstream of their dams being less susceptible to flooding and extreme low water (because the dams regulate the flow of water) and less polluted (because the dams filter the water and encourage sediment to drop out). Also, in the immediate vicinity of Beaver dams, ‘wetlands’ can develop, with the river ‘spilling over’ onto surrounding land. Along with the felled deadwood, an ideal habitat is created for many species of wildlife. Finally, Beavers are one of those charismatic mammals that encourage eco-tourism, with potential benefits for the local economy.

So, what is not to like? Well, the created ‘wetland’ areas can result in the loss of valuable farmland. With regard to farming costs, if agricultural crops are close to the water Beavers will sometimes feed on these, although this seems to be rather limited. Burrowing activity can lead to the erosion/destabilisation of river banks and compromise nearby structures. Tree felling by Beavers can be beneficial, but can also lead to the loss of valued trees. With regard to the effects of Beaver activities on fish, this is a complex issue that has yet to be fully resolved. Concerns include the potential for Beaver dams to impede fish migration. Of course, steps can be taken to mitigate these problems, but this does require proactive management. Overall, it seems that reintroduction is an interesting and exciting possibility, but not without its complications.