In pursuit of beavers

I’m taking a temporary break from writing about the unfashionable end of British biodiversity to gaze out across a Scottish loch at a large hemispherical construction built from tree trunks and branches.  The loch is Loch Linne, about 10 kilometres from Lochgilphead in Argyll and the structure in front of me is a beaver lodge.  I’ve just walked to where I am standing from Loch Coille-Bharr, where an even more impressive structure, a dam stretching for some 50 metres, has blocked the narrow outflow stream from the smaller Dubh Loch, almost doubling this loch’s size as a result.

Knapdale_beavers_#1

Left: the beaver lodge at Loch Linne, Knapdale and, right, the dam between Dubh Loch and Loch Coille-Bharr.  Both are part of the Scottish Beaver Trial in Knapdale Forest, Argyll and Bute, Scotland.

Beavers were once indigenous to Britain but were hunted to extinction, largely because of the value of their fur (see Vermeer’s Hat by Timothy Brook for a fascinating account of the beaver trade).  The Knapdale Forest region is the location for a large scale trial to investigate the possibility of reintroducing beavers more widely in Scotland.   As I have a long-standing interest in what we mean by a “natural” ecosystem, I’ve been following this trial with interest.

Beavers live on a diet of aquatic vegetation and the dams are a means of flooding lake and stream margins in order to create extra habitat with water deep enough for them to swim.  It takes a lot of timber to build the dam and the lodge and we can see the evidence in the gnawed stumps of trees around the loch margin.  As an ecological curiosity these very visible signs of an elusive mammal in a remote area are fascinating, and the flooded landscapes that they create is host to many other types of wildlife.   However, you wouldn’t want a family of beavers living too close to your own land. Part of the irony of the Knapdale trial is that new raised paths have had to be built to let visitors access areas that the beaver have flooded.  As ever in ecology, ‘nuisance’ is a matter of perception and proximity, never an absolute.  A couple of years ago I told a German colleague about this project and he turned to me with an incredulous look on his face and said “you must be mad: we’ve been trying to get rid of them for years”.

Knapdale_beavers_#2

Left: the beaver lodge at Loch Linne, Knapdale and, right, the dam between Dubh Loch and Loch Coille-Bharr. Both are part of the Scottish Beaver Trial in Knapdale Forest, Argyll and Bute, Scotland.

The other thought that passes through my mind as I look at the beaver’s engineering exploits is how little we can ever understand about the ‘natural’ condition of our landscape purely by looking at contemporary evidence.   We all come to Scotland with pre-conceptions about babbling highland burns.  Yet, if we turn back the clock 400 years to a time when beavers were common in Scotland, then a proportion of those burns will have been dammed, with the water spilling out of the channel and flooding the valley floor.  The animals and plant communities that would have lived in those streams would  have been similar to those we find today in remote regions of Scotland, but not identical. Some species that we think of as rare would have been more common and vice versa.  This is of more than just semantic interest as ecologist’s views of the past defines our expectations for  modern aquatic ecosystems. Sometimes it is good to be reminded that we can, at best, look at the past as through a glass, darkly.

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