“Britain’s water voles used to be everywhere but numbers have plummeted by 97% since the 1970s – mink are eliminating them left, right and centre,” said Bill Amos.

A University of Cambridge professor specialising in evolutionary genetics is collaborating on a project to eradicate mink from the UK’s waterways.

Since 2020, the Waterlife Recovery Trust has set hundreds of traps across the East of England, and earlier this year, they declared East Anglia free of this invasive species.

DNA analysis is crucial in this effort, allowing researchers to track the animals’ movements and prevent their re-entry into cleared areas.

The team was surprised to discover that nearly all mink family members were found within a 15 km (nine-mile) radius of each other.

“If you don’t know how far mink are moving, you don’t know the area you have to clear before you can be fairly sure they’re not coming back by immigration, so that’s where the genetics comes in big time,” said Prof Amos.

“By analysing DNA samples taken from the caught mink, we can estimate the relatedness between them.”

American mink, which spread across the UK after escaping or being released from now-illegal mink farms, have no natural predators.

These “powerful animals,” as Professor Amos describes them, are capable of attacking birds as large as herons, as well as fish, seabirds, and particularly vulnerable species like kingfishers and water voles.

Volunteers from the Waterlife Recovery Trust use smart traps baited with an extract from mink anal glands to lure the animals.

Once a mink is caught, an alert is sent to a volunteer, and the animal is humanely euthanised.

For the past two years, there has been no evidence of mink reproduction in East Anglia.

Prof Amos said: “What’s spectacular about these results is that as well as the core area, we also have a 70km-wide [about 45 miles] buffer zone around it where we’ve been doing intense mink trapping, and this year the buffer zone was almost clear, too.”

As a consequence, water vole numbers are bouncing back.

Prof Tony Martin, the driving force behind Waterlife Recovery Trust, said: “The recovery of wildlife here in the eastern counties has been remarkable in the absence of their nemesis.

“This is that rare thing – an environmental good-news story.”

The project is now expanding, with plans to extend the trapping area to England’s southern coast and north to the Humber estuary.

 

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