[1] European mink numbers began to shrink during the 19th century, with the species rapidly becoming extinct in some parts of Central Europe.

During the 20th century, mink numbers declined all throughout their range, the reasons for which having been hypothesised to be due to a combination of factors, including climate change, competition with (as well as diseases spread by) the introduced American mink, habitat destruction, declines in crayfish numbers and hybridisation with the European polecat.

[7] Fossil finds of the European mink are very rare, thus indicating the species is either a relative newcomer to Europe, probably having originated in North America,[8] or a recent speciation caused by hybridization.

Genetic analyses indicate, rather than being closely related to the American mink, the European mink's closest relative is the European polecat (perhaps due to past hybridization)[3] and the Siberian weasel,[4] being intermediate in form between true polecats and other members of the genus.

hungarica (Éhik, 1932) The European mink is a typical representative of the genus Mustela, having a greatly elongated body with short limbs.

However, compared to its close relative, the Siberian weasel, the mink is more compact and less thinly built, thus approaching ferrets and European polecats in build.

[17] The European mink's skull is less elongated than the kolonok's, with more widely spaced zygomatic arches and has a less massive facial region.

Fur colour is evenly distributed over the whole body, though in a few cases, the belly is a bit lighter than the upper parts.

[21] The European mink's skull is much less specialised than the American species' in the direction of carnivory, bearing more infantile features, such as a weaker dentition and less strongly developed projections.

[5] The European mink does not form large territories, possibly due to the abundance of food on the banks of small water bodies.

The current range includes an isolated population in northern Spain and western France, which is widely disjunct from the main range in Eastern Europe (Latvia, Estonia, Belarus, Ukraine, central regions of European Russia, the Danube Delta in Romania and northwestern Bulgaria).

[25] The earliest actual records of decreases in European mink numbers occurred in Germany, having already become extinct in several areas by the middle of the 18th century.

The decline of the European mink in Estonia and Belarus was rapid during the 1980s, with only a few small, fragmented populations in the northeastern regions of both countries being reported in the 1990s.

The decline of European mink numbers in Ukraine began in the late 1950s, with now only a few small and isolated populations being reported in the upper courses of the Ukrainian Carpathian rivers.

Their numbers in Moldova began to drop very quickly in the 1930s, with the last known population having been confined to the lower course of the River Prut on the Romanian border by the late 1980s.

The core of their range was in the Tver Region, though they began to decline there by the 1990s, which was worsened by a colonisation of the area by the American mink.

[7] Habitat-related declines of European mink numbers may have started during the Little Ice Age, which was further aggravated by human activity.

[5] As the European mink is more dependent on wetland habitats than the American species, its decline in Central Europe, Estonia, Finland, Russia, Moldova and Ukraine has been linked to the drainage of small rivers.

In mid-19th-century Germany, for example, European mink populations declined in a decade due to expanded land drainage.

Although land improvement and river dredging certainly resulted in population decreases and fragmentation, in areas which still maintain suitable river ecosystems, such as Poland, Hungary, the former Czechoslovakia, Finland and Russia, the decline preceded the change in wetland habitats, and may have been caused by extensive agricultural development.

[7] Twenty-seven helminth species are recorded to infest the European mink, consisting of 14 trematodes, two cestodes and 11 nematodes.

[5] In the early 20th century, northern Europe underwent a warm climatic period which coincided with an expansion of the range of the European polecat.

A polecat-mink hybrid has a poorly defined facial mask, yellow fur on the ears, grey-yellow underfur and long, dark brown guard hairs.

Fairly large, the males attain the peak sizes known for European polecats (weighing 1,120–1,746 g (2.469–3.849 lb) and measuring 41–47 cm (16–19 in) in length), and females are much larger than female European minks (weighing 742 g (1.636 lb) and measuring 37 cm (15 in) in length).

Originally bred for their fur (which was more valuable than that of either parent species), the breeding of these hybrids declined as European mink populations decreased.

During the summer period, the diet of wild polecat-mink hybrids is more similar to that of the mink than to the polecat, as they feed predominantly on frogs.