Because the beaver isn't just an animal; it's an ecosystem!

The Martinez Beavers

Devon Beavers

Share the beaver gospel!

Do you remember the beaver project in Devon England where a few brave souls were arguing for their reintroduction by showing what good impact a pair had on fenced land? Well here’s their initial report of how things are going.


In March 2011 a pair of juvenile Eurasian beavers (Castor fiber) were released into a 3 hectare fenced enclosure on private land in northern Devon. The objectives of the project are to use beavers to restore an area of nationally important wet grassland and to understand the effects that this native, but UK extinct, species will have on this environment.

This project aims to study the effects that beavers have on these wetland. This will help to inform future decisions about the potential reintroduction of this species into the wider countryside.

 Ahh pull up a chair. Let’s see how beavers get on in the rolling grasslands of Devon. Remember that I myself am the grandaughter of a Cornish tin miner from St. Austell (prounced almost as ‘Ozil’). My grandfather was brought as a boy to work the gold mines in Sierra City when the tin mines stopped paying. (Look up the name ‘Perryman’ the next time your in the southlands!) This beaver sight is just off the Tamar river which bordered Cornwall from the rest of England. It used to be said that a man would be born, live his life and die without ever crossing the Tamar. And that if misfortune made you cross it you had encountered an evil fate indeed.

Beaver release

On 16th March 2011 a pair of beavers were released into the enclosure. The male and female beavers were both selected from captive bred animals of the eastern race of Eurasian beavers that originated in Bavaria. They were two years old at the time of release and were housed together for a number of weeks prior to being moved into the enclosure.

The beavers were placed directly into an artificial log and turf lodge that had been constructed alongside a small pond. All had been carefully designed to help the beavers settle in their new surroundings.

Although the beavers had transponders implanted into them, it was decided, for welfare reasons, that they should not have radiotracking devices attached to them. Instead they have been monitored using a network of camera traps located in various places within the enclosure.

Can I just stop and say how much I love that decision! Let’s try actually watching the animals instead of radio tracking them! Hurray for Devon! Shhh it gets better…


Prior to works commencing in 2010 open water was restricted to a trickle of water that flowed through the woodland, and only in parts was this a defined channel. In the woodland, a few pools could be found under upturned root plates of windblown trees.

By March 2012 (end of first year) a total of 8 large ponds had been created, with a total surface area of over 900m².

That’s right Devon! Imagine what our beaver would have done if the flow device had never been installed and city streets weren’t important! The pond used to go up above the level where we stand now, and it could easily have reached to Castro Street or beyond. All that stream complexity makes a huge difference in the creatures that can be sustained by that water. Just look:

The open water habitats are readily being colonised by a wide range of aquatic invertebrates, and this is expected to further increase as the ponds become more stable. 16 species of water beetle, four stonefly species, five caddis fly species, five dragonflies and a range of other groups were all recorded over three visits in the summer 2012.

It’s a great look at the effects of some beavers left to their own devices. You might want to check out the whole thing. What happens when all those bugs show up? Well all the things that eat bugs can’t wait to stop by.

For amphibians like common frogs there were limited opportunities for breeding prior to the introduction of beavers. A walkover survey in spring 2011 identified ten clumps of frog spawn, mainly in disturbed ground. By the spring of 2013, 310 clumps of frogspawn were counted, and 75% of these clumps were found in the shallow margins of four of the beaver ponds.

 As an anecdotal observation at the start of the project, most of the woodland was easily navigable in wellington boots. However, some parts of it are now so treacherous, that surveyors risk sinking to their waists. The range of additional ecological niches that have been created is impressive, possibly at the expense of areas of dense mature willow woodland.

I can’t wait to see what the next couple of years will bring. Thanks Devon for doing such a thoughtful and responsible job showing the world what beavers can do, and thanks Duncan Halley for sending me the report!