Interloper is beavering away

NATURAL England must decide whether beavers introduced to the River Otter, in Devon, can be allowed to remain. On January 28, it announced a five-year programme of monitoring by the Devon Wildlife Trust.

‘Keystone’ species radically alter the ecology of an area. The beaver is the textbook example. This ‘civil engineer’ of the natural world can change an aquatic landscape with the dams it builds and the pools that form behind them. The last beaver in Sweden, for example, was killed in 1871, but alterations to the landscape centuries ago can still be seen.

Beavers have been living wild on an 18km stretch of the Otter for the past five years. Nobody knows where they came from. Captive animals either escaped or were released to the wild. The odds were against their survival but, last year, adults with young were filmed near Ottery St Mary; these illegal immigrants, it seems, are there to stay.