The fight back by Britain's otters sees a decline in American mink

September 11, 2006

An otter.Credit: Pat Morris MTUK

A study by Oxford’s Wildlife Conservation Research Unit (WildCRU) suggests that native otters are driving American mink from Britain’s riverbanks. Researchers found a significant relationship between the decline in mink signs and the increase in those of otters, suggesting that returning otters may be driving the reduction of mink.

For the last thirty years mink, the descendants of escapees from fur farms, have been causing havoc among the native population – killing fish, birds and mammals. The hope now is that that decline has been reversed.

Water voles have been disappearing rapidly for decades as a result of habitat loss and mink predation, so the increase in the otter population is welcome news for those concerned about safeguarding the water vole. The highly endangered water vole is now at risk of national extinction and the study concludes: ‘Mink control, at least locally, is likely to be necessary to ensure the survival of water vole populations in many areas.’

The study is part of a long-term research programme examining the recovery of the otter population since their decline in the 1960s and 1970s. Large numbers died of poisoning from dieldrin, the since banned sheep dip found in fish eaten by otters. The devastation in the otter population left the way open for mink to flourish, but it seems the fight back has begun as the numbers of otter has increased. It appears that otters have driven mink out of rivers in western and northern England but in the south and east, mink are still a problem.

The study appears in the report The State of Britain’s Mammals 2006 published by the Mammals Trust UK.

Professor David Macdonald, from WildCRU, said: ‘ An increasing number of specialists and amateurs have worked very hard at conserving Britain’s mammals and our report is a synthesis of their achievements. Knowledge is really deepening, but so too is the realisation that solving many conservation problems is technically difficult – scientific evidence is the bedrock of sensible policy.’

Source: University of Oxford