Reintroductions


Why did beavers become extinct in Cumbria?


The answer really is that they are relatively easy to hunt (they live in an obvious place and are creatures of habit) and so many bits of them are, or were, useful to people and they were hunted to extinction as a result. Parts of beaver were used in traditional medicine and their secretion,


‘castoreum’, was used in medicines and in perfumes (l’eau de beavers botom, anyone?). They taste nice and are rich in fats, and the Catholic Church conveniently classified them as fish so that they could be eaten on Fridays. But what really seems to have sealed their fate is the wonderful quality of their fur, which is both very warm and waterproof. It comes in two layers: the water-shedding outer layer of guard hairs and the under-fur, which can be made into top-quality felt. Many old photographs of Victorian gents and ladies show beaver top hats, coats with beaver fur collars and beaver trimmings. The quest for beaver fur was one of the factors driving the exploration and conquest of North America and Siberia.


And the reason for that need to travel into inhospitable and remote places to trap beavers? They were already extinct everywhere nearer home. Indeed, the Eurasian beaver came close to being completely wiped out. Extinction for beavers in Cumbria came early. We know this because Giraldus Cambrensis, writing in 1188, talks of beavers in Britain surviving only on the River Teifi in Wales and one (unspecified) river in Scotland. The account is probably second hand and may not be wholly accurate, but it is clearly describing an animal that is not widespread or common.


What effect did the extinction of beavers have on the natural environment?


Beavers are regarded as ecosystem engineers, adapting the environment for their own benefit. Their tree-felling opens up river and stream channels to the light; their dams slow the flow of water, trap silt and create deep, cool pools.


So, exterminating beavers would have meant shallower, simpler stream systems, more enclosed by trees and with a much higher silt load. The species that use these kinds of habitats, including amphibians, dragonflies, litle grebe, moorhens and water voles would all have suffered as their habitat declined. The species that eat fish and frogs, such as grey herons and oters, would have declined with declining food availability. As well as this, now long-extinct species like white stork and common crane would have declined for the same reason.


One of the things about beavers is that their dams aren’t permanent because they eventually run out of accessible tree bark to eat and wood to mend their dams with, and so the dams eventually fail. This leaves behind something known as a ‘beaver meadow’, usually covered in wetland plants such as sedges. These are used by grazing animals that live in forest environments and so the populations of forest grazing animals would have declined also. So removing a keystone species like the beaver has knock-on effects on a whole host of other species, some of them not particularly closely associated with the wetland habitats that beavers create.


What does the future hold?


It looks quite interesting! A partnership of different organisations and private landowners led by Cumbria Wildlife Trust has been talking about reintroducing beavers to Cumbria for a couple of years now. At the moment there are three trials making progress, two with private landowners and one on the land of another conservation organisation. The reintroductions would be on a closely monitored, trial basis into fenced enclosures as opposed to a general release. I can’t say too much more really as each reintroduction proposal needs a licence, will need to show what it contributes to our understanding of beavers in modern UK, needs a monitoring scheme and an


‘exit strategy’, and will need to have a local consultation.


We will keep you informed with news as this work progresses.


 If a reintroduction project goes ahead, beavers could soon be seen in


Cumbria for the first time since they were hunted to extinction Photo: Nick Upton – Cornwall Wildlife Trust


www.cumbriawildlifetrust.org.uk 19


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