Traps Scented Like Mink Butts Could Be Key to Removing the Invasive Species From the U.K.

Large numbers of American mink—coveted for their fur, used to make coats, bags and other luxury items—were brought to the United Kingdom decades ago by traders. The mammals lived in captivity and reproduced in fur farms, which numbered in the hundreds at the industry’s height during the 1950s.

But soon, the minks escaped from these farms, and some were freed by animal rights activists in the 1990s. When they entered British and Irish ecosystems, the non-native creatures disrupted—and in some cases, entirely decimated—local wildlife populations that had not adapted to their hunger and keen hunting skills.

Using their exacting sense of smell, minks prey on small animals—including salmon, moorhens, kingfishers and frogs. They gobble up nestfuls of rodents called water voles, which have declined by about 96 percent in Britain since 1950. And regional seabird populations, which are already suffering due to avian influenza outbreaks, have accordingly dropped where minks are present, as they often eat eggs and chicks near shores.

The destructive species has become a thorn in the side of biologists, who for years have tried and failed to eradicate the animals. Now, however, a trial using 441 new “smart” traps has eliminated minks from about 5 percent of England, effectively clearing them from an area in the region of East Anglia.

Until recently, it was widely considered that minks had become too established in the English wild to ever be completely removed. But that was before Tony Martin, a world-renowned expert in addressing non-native predators, turned his attention to the minks. Martin had previously led a successful removal project focused on invasive rodents that devoured native birds on the island of South Georgia—freeing it of mice and rats for the first time in roughly 250 years.

To tackle Britain’s mink problem, a number of regional conservation charities and water management organizations founded the Waterlife Recovery Trust, of which Martin was named the chair. The group devised a four-year trial across central and eastern Norfolk and Suffolk, an area spanning about 2,300 square miles. At the center of the effort, which went live in 2020: a first-of-its-kind “smart” mink trap.

“If you’ve got the right plan, then it’ll work on any scale you like,” Martin says to New Scientist’s Michael Le Page.

The group’s plan consisted of two key elements. The first was a technological advance in the traps—each had a sensor inside, which would alert them when its door closed. This would signal to the team that a mink was caught, allowing them to reach the animals more efficiently. It also eliminates the need to check the hundreds of traps daily, saving the team precious time. When a mink was contained, it was shot with an air rifle, which Martin tells the Independent’s Danny Halpin is the most humane way to do it.

The second part of the plan was the lure: They attracted the animals with a scent from a mink’s anal gland, which they call “eau de mink.”

Along with hundreds of volunteers, biologists hung hollow plastic balls inside the traps. Each ball was filled with cigarette filters that had been dampened with one or two drops from captive minks’ anal glands—an irresistible pheromone for wild minks following their powerful noses.

Four years later, in 2023, the team found no evidence of mink reproduction throughout the study area, and the water vole population in Norfolk and Suffolk had significantly increased, compared to in other regions where traps weren’t set.

“The trial results are encouraging, and we hope will help recover water vole populations, and benefit other species which have been affected by American mink,” says Julie Hanna, a species conservation adviser for Natural England, the government’s wildlife advisory body, to Patrick Barkham of the Guardian.

Invasive species removal can sometimes become an ethical minefield. Countries worldwide have grappled with eradicating one species to save another. (A recent plan proposed to kill 470,000 barred owls in the Pacific Northwest to protect northern spotted owls.) In the case of the mink, Martin argues that choosing not to kill them will still result in the death of wildlife.

“The thing that people sometimes struggle with is this thing of, how can you kill them? What gives you the right?” he tells the Independent. “They don’t see mink chewing the heads off young kingfishers or going into a nest of water voles and eating all the young.”

The team’s next steps are to expand their new trapping method across the entire country—an effort that, if successful on such a scale, would be the largest-ever eradication of a non-native species.

“We now have a golden opportunity to fix a problem we’ve inherited and not simply pass on an even more impoverished natural world to the next generation,” says Martin to Andy Trigg of BBC News. “Nature has a remarkable ability to bounce back, given half a chance. Let’s give it that chance.”

Christian Thorsberg | READ MORE

Christian Thorsberg is an environmental writer and photographer from Chicago. His work, which often centers on freshwater issues, climate change and subsistence, has appeared in Circle of Blue, Sierra magazine, Discover magazine and Alaska Sporting Journal.