Mustela lutreola

The European mink (Mustela lutreola), also known as the Russian mink and Eurasian mink, is a semiaquatic species of mustelid native to Europe. It is similar in colour to the American mink, but is slightly smaller and has a less specialized skull. Despite having a similar name, build and behaviour, the European mink is not closely related to the American mink, being much closer to the European polecat and Siberian weasel (kolonok). The European mink occurs primarily by forest streams unlikely to freeze in winter. It primarily feeds on voles, frogs, fish, crustaceans and insects. The European mink is listed by the IUCN as Critically Endangered due to an ongoing reduction in numbers, having been calculated as declining more than 50% over the past three generations and expected to decline at a rate exceeding 80% over the next three generations. European mink numbers began to shrink during the...

The European mink is mostly restricted to Europe. Its range was widespread in the 19th century, with a distribution extending from northern Spain in the west to the river Ob (just east of the Urals) in the east, and from the Archangelsk region in the north to the northern Caucasus in the south. Over the last 150 years, though, it has severely declined by more than 90% and been extirpated or greatly reduced over most of its former range. 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). It occurs from sea level to 1,120 m (1,220 yd). In Estonia, the European mink population has been successfully re-established on the island of Hiiumaa, and a project to re-establish them on the nearby island of Saaremaa is underway, with the first minks arriving in 2022.

The European mink has a diverse diet consisting largely of aquatic and riparian fauna. Differences between its diet and that of the American mink are small. Voles are the most important food source, closely followed by crustaceans, frogs and water insects. Fish are an important food source in floodlands, with cases being known of European minks catching fish weighing 1–1.2 kg (2.2–2.6 lb). The European mink's daily food requirement is 140–180 grams (4.9–6.3 oz). In times of food abundance, it caches its food.

The European mink does not form large territories, possibly due to the abundance of food on the banks of small water bodies. The size of each territory varies according to the availability of food; in areas with water meadows with little food, the home range is 60–100 hectares (150–250 acres), though it is more usual for territories to be 12–14 hectares (30–35 acres). Summer territories are smaller than winter territories. Along shorelines, the length of a home range varies from 250–2,000 m (270–2,190 yd), with a width of 50–60 m (55–66 yd). The European mink has both a permanent burrow and temporary shelters. The former is used all year except during floods, and is located no more than 6–10 m (6.6–10.9 yd) from the water's edge. The construction of the burrow is not complex, often consisting of one or two passages 8–10 cm (3.1–3.9 in) in diameter and 1.40–1.50 m (1.53–1.64 yd) in length, leading to a nest chamber measuring 48 cm × 55 cm (19 in × 22 in). Nesting chambers are lined with straw, moss, mouse wool and bird feathers. It is more sedentary than the American mink, and will confine itself for long periods in its burrow in very cold weather.

longest observed 8.5 years.

During the mating season, the sexual organs of the female enlarge greatly and become pinkish-lilac in colour, which is in contrast with the female American mink, whose organs do not change. In the Moscow Zoo, estrus was observed on 22–26 April, with copulation lasting from 15 minutes to an hour. The average litter consists of three to seven kits. At birth, kits weigh about 6.5 grams (0.23 oz), and grow rapidly, trebling their weight 10 days after birth. They are born blind; the eyes open after 30–31 days. The lactation period lasts 2.0 to 2.5 months, though the kits eat solid food after 20–25 days. They accompany the mother on hunting expeditions at the age of 56–70 days, and become independent at the age 70–84 days.

During the mating season, the sexual organs of the female enlarge greatly and become pinkish-lilac in colour, which is in contrast with the female American mink, whose organs do not change. In the Moscow Zoo, estrus was observed on 22–26 April, with copulation lasting from 15 minutes to an hour. The average litter consists of three to seven kits. At birth, kits weigh about 6.5 grams (0.23 oz), and grow rapidly, trebling their weight 10 days after birth. They are born blind; the eyes open after 30–31 days. The lactation period lasts 2.0 to 2.5 months, though the kits eat solid food after 20–25 days. They accompany the mother on hunting expeditions at the age of 56–70 days, and become independent at the age 70–84 days.

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. A similar pattern occurred in Switzerland, with no records of minks being published in the 20th century. Records of minks in Austria stopped by the late 18th century. By the 1930s–1950s, the European mink became extinct in Poland, Hungary, Czechoslovakia and possibly Bulgaria. In Finland, the main decline occurred in the 1920s-1950s and the species was thought to be extinct in the 1970s, though a few specimens were reported in the 1990s. In Latvia, the European mink was thought to be extinct for years, until a specimen was captured in 1992. In Lithuania, the last specimens were caught in 1978–79. 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. In Romania, the European mink was very common and widely distributed, with 8000–10,000 being captured in 1960. Currently, Romanian mink populations are confined to the Danube Delta. In European Russia, the European mink was common and widespread in the early 20th century, but began to decline during the 1950s–1970s. 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. Between 1981 and 1989, 388 European minks were introduced to two of the Kurile Islands, though by the 1990s, the population there was found to be lower than that originally released. In France and Spain, an isolated range occurs, extending from Brittany to northern Spain. Data from the 1990s indicate the European mink has disappeared from the northern half of this previous range.

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, or a recent speciation caused by hybridization. It likely first arose in the Middle Pleistocene, with several fossils in Europe dated to the Late Pleistocene being found in caves and some suggesting early exploitation by humans. 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) and the Siberian weasel, being intermediate in form between true polecats and other members of the genus. The closeness between the mink and polecat is emphasized by the fact the species can hybridize.