European mink  (Mustela lutreola)

The European mink is classified as Critically Endangered (CR) on the IUCN Red List (1), and listed on Appendix II of the Bern Convention (4).

The European mink (Mustela lutreola) is one of Europe’s most endangered mammals. It is a medium sized mustelid with a long, slender, arched body, short legs and a short bushy tail (2). The fur is normally blackish-brown with a distinctive small band of white fur around the upper and lower lips and occasionally on the throat (5). This marking and its smaller size usually distinguishes the European mink from the American mink, Mustela vison (6), but occasionally individuals may look so similar that only the skeleton or genetic analysis can guarantee correct identification (7).

The dense pelage of the European mink is short, even in the winter (8), but it has a thick, water-repellent undercoat which insulates the mink when swimming (5). The European mink also has other adaptations for a semi-aquatic lifestyle; its feet are partly webbed and therefore useful for swimming, diving and hunting underwater (7). However, its eyesight is not well adapted to seeing underwater. Mink rely heavily upon their sense of smell when foraging for terrestrial prey (7).

Male and female European mink look very similar, but the males are up to 80 percent larger than the females (2). Young mink are similar in appearance to the adults (7).

A century ago the European mink could be found throughout the European continent, but its populations have severely declined and it is now extinct or greatly reduced over most of its former range (7). It is known to survive only in small numbers in parts of Eastern Europe and some areas of Spain and France (6).

Mink are semi-aquatic animals and inhabit densely shaded banks of lakeshores, rivers, streams and marshlands (7). They are rarely found more than 100 metres away from fresh water (8).

Mink may live within muskrat (Ondatra zibethicus) huts and burrows. If these are abandoned the mink will simply move in, but they may also take over occupied huts, killing and eating the inhabitants (2). Mink will also make dens in natural cavities in stream banks, under trees and in drift piles, lining them with grass, leaves, fur or feathers (8).

Mink are mainly nocturnal, emerging from their dens to feed at night on a diet of small animals, including water voles, birds, frogs, molluscs, crabs, fish and insects (6). This range of prey, hunted in water, on land, in swamps and in burrows, is considerably greater than the range of more specialised mustelids like otters and weasels. This carries both costs and benefits, as a specialised hunter will be better adapted than a generalist at exploiting certain prey, but a generalist, like the mink, has the advantage of being able to hunt different prey should one type become scarce (7).

The European mink is a wanderer, occupying large home ranges of up to 15 kilometres of river, and rarely using the same den (3). The female usually stays close to the den, unless a shortage of food drives it to find another location (2). The European mink leads a solitary lifestyle, except during the breeding season, from February to March (8), when it seeks out a mate using a repertoire of sounds from hisses and screams to chuckling calls. Males first seek out the females whose territories overlap their own, before searching further afield (7).

Mating in the European mink is often preceded by very aggressive encounters between the two sexes. The females’ gestation period is between five and ten weeks, with the birth occurring in the spring when there is an abundance of food and shelter (2). The female European mink will give birth to between two and seven young per litter and raises them alone in a den, suckling them for five to six weeks (5). Mink are born blind and helpless, and so depend on the female until they are weaned at about 10 weeks, leaving the den after 12 to 18 weeks. This species reaches maturity after one year, and lives for about 6 years in the wild and up to 12 years in captivity (2).

Populations of the European mink have suffered from a series of ecological and commercial threats (5). Habitat loss and degradation are serious threats to this sensitive species in parts of Europe (1) (8), where hydroelectric developments and water pollution have increased significantly over the past few decades (8).

Another major reason for the decline of the European mink is commercial trapping for its fur (1) (5). Although the fur of this species is less valuable than that of the American mink, M. vison (8), overexploitation has resulted in a weakened population (1). In addition, the introduction of the larger American mink in 1926 has created severe competition with the European mink for food and habitat, and has significantly reduced this native species’ population (6).

Accidental mortality through pest control trapping, unintentional poisoning and vehicle collisions is particularly frequent in western parts of the European mink’s range. All mink species are also susceptible to Aleutian disease (1), a highly contagious virus which causes persistent infection and can often be lethal (9).

As a result of these threats, the European mink population is thought to have declined by over 90 percent since the start of the 20th century, and is now small, fragmented, and continuing to decline (1).

In 2011, the IUCN upgraded the status of the European mink from Endangered (EN) to Critically Endangered (CR) due to an ongoing population decline (1). There are many captive breeding programmes underway for this species in many range states, which are attempting to successfully establish new European mink populations. Further research is also being undertaken into the European mink’s reproduction, artificial insemination and responses to captivity, to assess the viability of captive breeding as a technique for its conservation (1).

In Spain and France, the populations of European mink seem to be suffering from inbreeding, which could be addressed by the introduction of new, captive-bred individuals. A six-year government programme was introduced in France in 2010 for conservation breeding and reintroduction, while a number of other conservation initiatives are also in place in other countries in the European mink’s range (1).

In addition to these measures, efforts need to be made to restore and maintain areas of suitable habitat for the European mink, and to designate them as protected areas. Existing protected areas also need to be improved and maintained (1).

The impact of the American mink on local European mink populations is being monitored and controlled to reduce the impact of this non-native species, and efforts have been made to remove American mink in some areas. Further studies are needed to better understand the effects of the American mink on the European mink (1).

The European mink is legally protected in all the countries in which it occurs. A species action plan is needed within the European Union to help successfully conserve this highly threatened mustelid and to aid collaboration between different conservation initiatives (1).

View information on this species at the UNEP World Conservation Monitoring Centre.

More information on the European mink:

• Youngman, P.M. (1990) Mustela lutreola. Mammalian Species, 362: 1-3. Available at:
  http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-362-01-0001.pdf
• Fournier, P. and Maizeret, C. (2003) Status and conservation of the European Mink (Mustela lutreola) in France. In: International Conference on the Conservation of the European Mink, Logroño (La Rioja, Spain). (5 - 8 November 2003), pp. 21-24.