Country Gardener

Widely regarded as the authority on gardening in the south west

Beavers bite back

With beavers released in Cornwall and a breeding family on the River Otter in Devon, it’s easy to believe that the species is back in Britain for good, but a lot needs to be done to secure its future.

They are an unusual, characterful species, and far from liked by all.

Humans aside, beavers are the best loggers on the planet. Their dams, which they build to protectively raise water levels around their lodges upstream, enliven local ecology by coaxing in species which prefer slow-moving water, like dragonflies and frogs; in doing so, they can also alter the flow of rivers – always a contentious issue in land management.

Beavers have a positive effect on their environment through their behaviour. 

By gnawing on stems they 'coppice' trees like willow, hazel, rowan and aspen. The regrowth provides homes for a variety of insects and birds.

Wild beavers found living on the River Otter in Devon are a species which was once native to the UK, tests have confirmed. A breeding family was first spotted last year, although it is not known how they came to be there. DNA results have shown the beavers are Eurasian rather than North American.

Nature lovers have welcomed the first wild beaver families for hundreds of years. Hunted for their pelts, meat and scent glands, which were used in perfume and quack medicine, beavers became extinct in the UK by the 16th century.

Then they were trapped and killed for their luxurious pelts and their castoreum, waterproofing oil they secrete from two sacs near their genitals.

There are now three recognised populations in Britain. One in Knapdale, on the west coast of Scotland, is the result of the only official trial and numbers about 12. There are several hundred on the River Tay catchment on Scotland’s east side and some 30 on the River Otter in Devon – both these populations came from unlicensed releases. Other groups of unsanctioned wild beavers exist elsewhere, too. 

Beavers are so well established it would be almost impossible to eradicate them. But if they are to be more widely reintroduced, we need a programme of pragmatic beaver management, based on systems in other European countries, one that takes into account the interests of landowners.

The wetlands in which beavers live are valuable for many other species too. Animals like otters, water voles, water shrews and wildfowl such as teals all benefit. Craneflies, water beetles and dragonflies in turn support breeding fish and insect-eating birds like spotted flycatchers. 

BeaverscThere is a legal requirement to consider restoring beavers to their former range under the EU Habitats Directive and to protect them under the Bern Convention.

There have been more than 200 formal beaver reintroduction projects (plus numerous unofficial releases) in more than 26 European countries and their ecology and management is well-studied.

Beavers are well-known for their habit of damming streams, but if the water is deep enough, they have little need for dams.

Beavers construct homes called 'lodges'. They need water at least a metre deep outside their lodges so they can swim in, providing protection against predators. They prefer to swim, rather than walk and like to transport branches through water, so will make narrow canals to enable this. The dam creates water deep enough for them to swim in.

Beaver dams are temporary structures and generally quite leaky. By building new dams in different places, the beavers bring a changeable mixture of habitats into the landscape, with streams, pools and bare mud. 

Beaver dams also hold water in dry periods, help to lessen flash-flooding downstream and reduce erosion, improve water quality by holding silt and catch acidic and agricultural run-off.

What do beavers eat?

Beavers eat only plants and do not eat fish. They feed on aquatic plants, grasses, herbaceous plants and shrubs during the summer months and woody plants in winter. They will often store food underwater so that they can access it if the water freezes over in winter.

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