Non-native and damaging to UK ecology, the North American mink has triggered an alert from conservationists.

East Anglian Daily Times: The North American mink has been reported in an urban area of Colchester. Picture: ESSEX WILDLIFE TRUSTThe North American mink has been reported in an urban area of Colchester. Picture: ESSEX WILDLIFE TRUST (Image: Archant)

Essex Wildlife Trust has issued a plea for people to be vigilant after a series of sightings of unwelcome and ecologically damaging North American mink in an urban part of the county.

The charity has received several reports of the non-native predator in Colchester, with fish being taken from garden ponds.

Since the first Essex sighting of feral North American mink - at Abberton Reservoir in 1962 - the highly invasive species had spread across the county, the trust said. It wiped out water voles and other wildlife along most Essex rivers but in recent years the species had also appeared in urban areas of Romford, Chelmsford and Witham, usually close to a watercourse.

“Unfortunately, there have now been several sightings of a mink in the Straight Road area of Colchester, with records of it stealing fish from two separate garden ponds,” the trust said.

“This animal was initially mistaken for an otter. However, unlike this beloved native species, mink are extremely damaging in the UK environment and often roam much further from water. Because they can be aggressive it is not advised to approach a mink and if you live in the surrounding area you should also be watchful over pets that are kept outdoors while the mink is present in the area.”

Mink were “far smaller” than otters. They were better at climbing and were more likely to be seen during the day.

“Their fur is dark brown, looking almost black when wet, so they resemble a very dark-coated ferret. Essex Wildlife Trust has a dedicated Water for Wildlife officer - Darren Tansley - who is responsible for the Essex Water Vole Recovery Project, part of the Eastern Region Mink and Water Vole Project. With the help of hundreds of volunteers, water voles have been restored to much of north Essex over the past decade and the number of mink has been declining.

“However, these recent sightings show that mink are not afraid to enter highly urban areas and could create problems for people and wildlife in Colchester,” said the trust.

Mr Tansley added: “It is still unusual for mink to be found in such a dense urban area but it is likely the individual has come down through the Lexden Springs and is now enjoying the fruits of easy prey in people’s gardens. We keep a record of all mink sightings to monitor the species in Essex, so please get in touch if you see one and let us know where it was.”

In The Mammals of Essex, which Mr Tansley co-wrote with John Dobson, North American mink’s county staus is given as “common, decreasing where controlled.”

The only non-native mammalian predator to have successfully colonised the UK, they were imported from 1929 to be bred for the fur trade, but escappes were soon noted from widespread locations. Their spread across Essex had been “rapid”, covering most of the county, including urban locations.

Control in connection with the Essex Water Vole Recovery Project had been successful in the areas it covered - such as parts of the Tendring and Dengie peninsulas and the River Colne - but mink were “still found in good numbers throughout all other major inland rivers in Essex,” the book says.

“Their ability to disperse over long distances means they are likely to remain in established feature of our naturalised fauna for the foreseeable future,” it adds.

Essex Wildlife Trust wants to record all sightings of mink in Essex. Sightings should be sent to the Biological Records Centre website at www.essexwtrecords.org.uk/ or email darrent@essexwt.org.uk