Not the enemy
You’ll have heard of the notorious American mink, devastating our water voles, but what of the European mink? This little-known animal is not a monster – it’s probably the continent’s most endangered mammal, says Nick Funnell.
What makes European mink different to American mink?
THESE CUTE SLITHERS OF BROWN FUR SCOOTING AMONG THE POOLS ARE AN IRRESISTIBLE MIX OF SENSITIVE AND PSYCHO.
Asmall head darts out of the den entrance and sniffs the air. It vanishes back inside but returns seconds later, delicate nose twitching like crazy, shiny eyes peering all round, chocolate-brown fur immaculate in the Spanish sunshine. The dusty route through the undergrowth to the water ahead looks clear, but this wary creature won’t dare move until she’s certain.
This is Lluçanesa, a female European mink just over a year old. Her den is, sadly, not a cosy riverbank burrow but a wooden nesting box laden with sensors attached to her enclosure at the Fieb Foundation, a wildlife rescue and research centre about 50km outside Madrid, Spain.
It’s my first glimpse of one of these shy, semi-aquatic mustelids – a relative of the polecat and otter – and it unfortunately has to be here because you’re extremely unlikely to spot European mink in the wild. Not only do they prefer not to be seen, but they’re also among the continent’s most threatened carnivores and a strong contender for its rarest mammal.
European mink once roamed the riverbanks of much of continental Europe – though they were never UK natives – but are now relegated to a few isolated pockets in its far west and east. Fewer than 500 are thought to cling on in northeast Spain along the waterways of the Ebro and Cantabrian basins, while the Danube Delta and Dniester River in Romania/Ukraine may be home to 1,000–1,500. Some are also likely remaining in south-west France and Russia, but everywhere reliable figures are lacking. In Spain the last – and so far only – nationwide census dates from 2001.
The only thing we can be sure of is that the numbers are decreasing, and there is a real risk this Critically Endangered mammal could disappear – possibly in as little as five years in western Europe, WWF Spain has warned. “I think this is the last moment for the European mink,” says Fieb director and wildlife vet Silvia Villaverde.
If you’re suddenly realising you don’t know much about Europe’s most-endangered carnivore – don’t worry, you’re not alone. As a Brit who’s lived in Spain for the last decade, I’ve always been impressed by the country’s efforts to save the iconic Iberian lynx, but the European mink has never enjoyed the recognition that would guarantee the same stable support to safeguard its future.
Watching these cute slithers of brown fur scooting among the vegetation and pools of their Fieb enclosures, it’s hard to fathom why. Their characters are an irresistible mix of sensitive and psycho. “Compared with all the other species I’ve worked with, they’re the most delicate,” says Villaverde, adding that it can nevertheless take an hour to wrangle fiery females into a cage during breeding season. “They’re small, but they’re little thugs.”
For most people, ‘mink’ conjures up images of fur coats worn by Cruella de Vil types, and the fur trade is certainly
partly responsible for the animals’ disappearance. “The decline started at the end of the 18th century in central Europe,” explains Madis Põdra, who with partner Asun Gómez leads the European Commission-backed Life Lutreola Spain project, the only major European mink conservation programme in Spain.
“But mostly it’s because of habitat destruction,” Põdra says. “The channelling of rivers and more intensive agricultural work affected the freshwater habitat. And the European mink is quite sensitive to that.” Then at the start of the 20th century the fur trade further hastened the species’ decline. “In some years, 75,000 European mink were killed in Russia alone,” he says grimly.
Today the fur trade is less of a problem, but it has spawned an even bigger threat: American mink. As in the UK, these fur-farm escapees are having a devastating impact on the continent’s wildlife, and the European mink is right in the firing line. Although the two species aren’t closely related – the European mink has more in common with the polecat, with which it occasionally interbreeds – they inhabit the same ecological niche.
The bigger, brasher Americans muscle out their smaller European cousins wherever the two come into contact. And, as Gómez’s research has found, that doesn’t mean simply outcompeting them for resources, but direct violent confrontations. “We have seen how American mink have killed European mink.”
European mink also have lower breeding success and need larger territories to survive. Perhaps they are less
efficient at hunting the fish (mostly barbels, trout and minnows), small mammals, crayfish, reptiles, amphibians and birds on which they depend. So they quickly lose out when the invaders arrive, disappearing from the affected river within two to four years, says Põdra.
It’s no surprise that from their base in Haro, in the heart of the Rioja wine region, Gómez and Põdra are devoting most of Life Lutreola Spain’s resources to eradicating the American mink. And they have a highly effective weapon: the mink raft. Since 2015, they and their team of 200 technicians and rangers have cleared American mink from a 400km-stretch of the River Ebro and its tributaries, and their fleet of 1,000 rafts continues to ‘clean up’ other waterways in the Basque Country, La Rioja, Aragón and Valencia regions.
Four hundred kilometres away at the Fieb Foundation, I watch the comings and goings of Lluçanesa and the captive-breeding centre’s current population of 15 other European mink on a bank of monitors worthy of BBC Two’s Springwatch studio. In addition, there is another major facility in Lleida, Catalonia, and a smaller centre in the Basque Country. Together, they house 50 or so mink.
A host of cameras and sensors installed in their 35–110m2 enclosures monitor the mink round the clock. The aim is not simply to keep them safe, but also to collect valuable data. Since the Fieb Foundation started working with mink in 2013, it has tested scales and radio-frequency identification systems in the nesting boxes that detect how often the animals go in and out, as well as ceilingmounted 360° cameras – normally used to track humans in public spaces – to observe their behaviour.
This climate of innovation has helped the foundation find ingenious solutions to the problems associated with breeding European mink in captivity. Captive-born males, for instance, are less likely to exhibit mating behaviour than those brought in from the wild – normally you would expect it to be the other way round. To counteract this, the team has been encouraging the predatory instincts of the mink by introducing live prey in the form of mice trained to flee from their scent. . Soon tench will be offered too.
The centre has s just enjoyed its most successful year yet. Of the 16 adult mink living here in 2017 (eight males and eight females), five males exhibited mating behaviour ur and five females became pregnant. In all, 12 kits were born: double the 2016 total.
And there’s a back-up plan. The he Fieb team is talking king to researchers in n the USA to adapt pt
“EUROPEAN MINK NEED LARGER TERRITORIES THAN AMERICAN MINK TO SURVIVE, PERHAPS BECAUSE THEY’RE LESS EFFICIENT AT HUNTING PREY.”
pioneering techniques that rescued the Endangered blackfooted ferret, which very nearly went extinct in the Midwest prairies. Just 18 ferrets were left by the mid-1980s, so these charismatic little carnivores suffered a ‘genetic bottleneck’ where inbreeding caused by chronic lack of genetic diversity threatened the viability of the entire species. By taking all of the surviving ferrets into captivity to manage the population artificially, the species was saved at the eleventh hour. Targeted releases of carefully selected captive-bred ferrets followed.
Lying 20km off the coast of Estonia in the Baltic Sea, Hiiumaa Island was historically never home to European mink. But after the last wild individual in Estonia was captured in 1996, the 1,000km2 island’s distance from the mainland – and thus from marauding American mink – made it perfect for a similar reintroduction project. Every year between 2000 and 2016, captive-bred European mink were released on the island. Today, the population has reached about 100 and so the reintroductions have stopped.
RETURN TO THE WILD
Now Põdra, an Estonian, is hoping that his experience on Hiiumaa Island will lead to similar success in Spain. Life Lutreola released its first captive-bred European mink into the wild at two sites during August and September 2017. Eight mink were set free to reinforce an existing population on the Leizarán River in Gipuzkoa province in the Basque Country, while 11 more were released to build a new population on a 150km stretch of the River Aragón, where surrounding mountains and a dam have so far kept American mink out.
Only the least genetically valuable animals are picked for release. Success will take years, so keeping the captive population healthy is paramount. “Animals with genes that are less represented in the population will stay in captivity to maintain diversity,” Põdra explains. Since Spain’s
European mink population has particularly low genetic diversity, the plan is to start mixing it with the 250 or so individuals in the 25-year-old captive-breeding programme in Estonia. This will create a single captive population big enough to maintain diversity. “The Spanish and Estonian mink are not that different,” Põdra says. “Genetic studies show that the separation occurred quite recently.”
Following their release this summer, the 19 European mink are being radio-tracked to check their progress. Ensuring their survival means also keeping tabs on the advance of American mink, so Gómez and Põdra are aiming to undertake a new census of both mink species in Spain. But with the Life Lutreola scheme due to end in 2018, concerns remain over what happens next.
Hope is on the horizon at last, after the Spanish Environment Ministry decided in July 2017 to categorise the European mink as a species in a “critical situation”, following a WWF campaign and an IUCN open letter. WWF Spain is optimistic that the new status will pave the way for the government to provide resources for a more comprehensive emergency plan. But it also wants better coordination among the regional, central and European administrations.
Until such a plan is in place, those fighting to save mink have no option but to go on using whatever resources they can find to safeguard the species. The alternative is unthinkable. “Rivers have always been part of our lives, and you can’t conceive of rivers without European mink,” says Põdra. “Once the mink go, it’s like the river isn’t the same any more.”
Money and support will only be forthcoming if more of us understand the European mink’s plight. So tell the world. If ever you find yourself discussing the American mink, make sure you also remind people about its smaller, more vulnerable European cousin that’s in desperate need of help.
“YOU CAN’T CONCEIVE OF RIVERS WITHOUT EUROPEAN MINK. ONCE THE MINK GO, THE RIVER ISN’T THE SAME ANY MORE.”
Above: European mink favour densely vegetated riverbanks. Below: the Fieb Foundation is breeding mink in captivity to boost wild populations.
Life Lutreola Spain released its first captive-bred European mink into the wild in 2017. The River Aragón was one of the release sites.
European mink usually have litters of three to five young – fewer than American mink.
At the Fieb Foundation mink use wooden nesting boxes attached with sensors that monitor the mustelids.
A female forages at the shore of a small pond. European mink hunt a range of prey, including small mammals, fish, birds and amphibians.
Above: a female peers through the undergrowth. Below: Madis Põdra radio-tracks mink along the River Aragón.
Above: a European mink shakes off water after hunting in a forest stream.