European mink
Encyclopedia
The European mink also known as the Russian mink, is a semi-aquatic species of Mustelid
Mustelidae
Mustelidae , commonly referred to as the weasel family, are a family of carnivorous mammals. Mustelids are diverse and the largest family in the order Carnivora, at least partly because in the past it has been a catch-all category for many early or poorly differentiated taxa...

 native to Europe. It is listed by the IUCN as Endangered due to an ongoing reduction in numbers, having been calculated as being more than 50% over the past three generations. European mink numbers began to shrink during the 19th century, with the species rapidly becoming extinct in some parts of Central Europe
Central Europe
Central Europe or alternatively Middle Europe is a region of the European continent lying between the variously defined areas of Eastern and Western Europe...

. During the 20th century, mink numbers declined all throughout their range, the reason for which having been hypothesised to be due to a combination of factors, including climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

, competition with (as well as diseases spread by) the introduced American mink
American Mink
The American mink is a semi-aquatic species of Mustelid native to North America, though human intervention has expanded its range to many parts of Europe and South America. Because of this, it is classed as Least Concern by the IUCN. Since the extinction of the sea mink, the American mink is the...

, habitat destruction, declines in crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...

 numbers and hybridisation with the European polecat
European polecat
The European polecat , also known as the black or forest polecat , is a species of Mustelid native to western Eurasia and North Africa, which is classed by the IUCN as Least Concern due to its wide range and large numbers. It is of a generally dark brown colour, with a pale underbelly and a dark...

. In Central Europe and Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

, the decline preceded the introduction of the American mink, having likely been due to the destruction of river ecosystems, while in Estonia
Estonia
Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...

, the decline seems to coincide with the spread of the American mink.

It is similar in colour to the American mink
American Mink
The American mink is a semi-aquatic species of Mustelid native to North America, though human intervention has expanded its range to many parts of Europe and South America. Because of this, it is classed as Least Concern by the IUCN. Since the extinction of the sea mink, the American mink is the...

, but is slightly smaller and has a less specialised 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
European polecat
The European polecat , also known as the black or forest polecat , is a species of Mustelid native to western Eurasia and North Africa, which is classed by the IUCN as Least Concern due to its wide range and large numbers. It is of a generally dark brown colour, with a pale underbelly and a dark...

 and kolonok
Siberian Weasel
The Siberian weasel , also known as the Kolonok, is a medium-sized species of weasel native to Asia. It is classed as Least Concern for extinction by the IUCN, due to its wide distribution and presumably large numbers....

. The European mink occurs primarily by forest streams unlikely to freeze in winter. It primarily feeds on vole
Vole
A vole is a small rodent resembling a mouse but with a stouter body, a shorter hairy tail, a slightly rounder head, smaller ears and eyes, and differently formed molars . There are approximately 155 species of voles. They are sometimes known as meadow mice or field mice in North America...

s, frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...

s, fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s and insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s.

Evolution and taxonomy

Fossil finds of the European mink are very rare, thus indicating that the species is either a relative newcomer to Europe, probably having originated in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, or a recent speciation
Speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...

 caused by hybridization. It likely first arose in the Middle Pleistocene
Middle Pleistocene
The Middle Pleistocene, more specifically referred to as the Ionian stage, is a period of geologic time from ca. 781 to 126 thousand years ago....

, with several fossils in Europe dated to the Late Pleistocene
Late Pleistocene
The Late Pleistocene is a stage of the Pleistocene Epoch. The beginning of the stage is defined by the base of the Eemian interglacial phase before the final glacial episode of the Pleistocene 126,000 ± 5,000 years ago. The end of the stage is defined exactly at 10,000 Carbon-14 years BP...

 being found in caves and some suggesting early exploitation by humans. Genetic analyses indicate that, rather than being closely related to the American mink
American Mink
The American mink is a semi-aquatic species of Mustelid native to North America, though human intervention has expanded its range to many parts of Europe and South America. Because of this, it is classed as Least Concern by the IUCN. Since the extinction of the sea mink, the American mink is the...

, the European mink's closest relative is the European polecat
European polecat
The European polecat , also known as the black or forest polecat , is a species of Mustelid native to western Eurasia and North Africa, which is classed by the IUCN as Least Concern due to its wide range and large numbers. It is of a generally dark brown colour, with a pale underbelly and a dark...

 (perhaps due to past hybridization) and the kolonok
Siberian Weasel
The Siberian weasel , also known as the Kolonok, is a medium-sized species of weasel native to Asia. It is classed as Least Concern for extinction by the IUCN, due to its wide distribution and presumably large numbers....

, 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 that both species can hybridize.

Subspecies

, seven subspecies are recognised.

Build

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 kolonok
Siberian Weasel
The Siberian weasel , also known as the Kolonok, is a medium-sized species of weasel native to Asia. It is classed as Least Concern for extinction by the IUCN, due to its wide distribution and presumably large numbers....

, the mink is more compact and less thinly built, thus approaching ferret
Ferret
The ferret is a domesticated mammal of the type Mustela putorius furo. Ferrets are sexually dimorphic predators with males being substantially larger than females. They typically have brown, black, white, or mixed fur...

s and European polecat
European polecat
The European polecat , also known as the black or forest polecat , is a species of Mustelid native to western Eurasia and North Africa, which is classed by the IUCN as Least Concern due to its wide range and large numbers. It is of a generally dark brown colour, with a pale underbelly and a dark...

s in build. The European mink has a large, broad head with short ears. The limbs are short, with relatively well developed membranes between the digits, particularly on the hind feet. The mink's tail is short, and does not exceed half the animal's body length (constituting about 40% of its length). The European mink's skull is less elongated than the kolonok's, with more widely spaced zygomatic arch
Zygomatic arch
The zygomatic arch or cheek bone is formed by the zygomatic process of temporal bone and the temporal process of the zygomatic bone , the two being united by an oblique suture; the tendon of the Temporalis passes medial to the arch to gain insertion into the coronoid process...

es and has a less massive facial region. In general characteristics, the skull is intermediate in shape between that of the kolonok's and the European polecat's. Overall, the skull is less specialised for carnivory than that of polecats and the American mink
American Mink
The American mink is a semi-aquatic species of Mustelid native to North America, though human intervention has expanded its range to many parts of Europe and South America. Because of this, it is classed as Least Concern by the IUCN. Since the extinction of the sea mink, the American mink is the...

. Males measure 373-430 mm in body length, while females measure 352-400 mm. Tail length is 153-190 mm in males and 150-180 mm. Overall weight is 550-800 grams. It is a fast and agile animal, which swims and dives skillfully. It is able to run along stream bed
Stream bed
A stream bed is the channel bottom of a stream, river or creek; the physical confine of the normal water flow. The lateral confines or channel margins, during all but flood stage, are known as the stream banks or river banks. In fact, a flood occurs when a stream overflows its banks and flows onto...

s, and stay underwater for 1-2 minutes. When swimming, it paddles with both its front and back limbs simultaneously.

Fur

The winter fur of the European mink is very thick and dense, but not long, and quite loosely fitting. The underfur is particularly dense compared with that of more land-based members of the genus Mustela. The guard hairs are quite coarse and lustrous, with very wide contour hairs which are flat in the middle, as is typical in aquatic mammals. There is little difference in length between the hairs on the back and belly, a further adaptation to the European mink's semi-aquatic way of life. The summer fur is somewhat shorter, coarser and less dense than the winter fur, though the differences are much less than in purely terrestrial mustelids.

In dark coloured individuals, the fur is dark brown or almost blackish-brown, while light individuals are reddish-brown. Fur colour is evenly distributed over the whole body, though in a few cases, the belly is a bit lighter than the upper parts. In particularly dark individuals, a dark, broad dorsal belt is present. The limbs and tail are slightly darker than the trunk. The face has no colour pattern, though its upper and lower lips and chin are pure white. White markings may also occur on the lower surface of the neck and chest. Occasionally, colour mutations such as albinoes and white spots throughout the pelage occur. The summer fur is somewhat lighter, and dirty in tone, with more reddish highlights.

Differences from American mink

The European mink is similar to the American mink
American Mink
The American mink is a semi-aquatic species of Mustelid native to North America, though human intervention has expanded its range to many parts of Europe and South America. Because of this, it is classed as Least Concern by the IUCN. Since the extinction of the sea mink, the American mink is the...

, though there are several important differences. The tail is longer in the American species, almost reaching half its body length. The winter fur of the American mink is denser, longer and more closely fitting that that of the European mink. Unlike the European mink, which has white patches on both upper and lower lips, the American mink almost never has white marks on the upper lip. 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. The European mink is reportedly less efficient than the American species underwater.

Territorial and denning behaviours

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 hectare
Hectare
The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...

s, though it is more usual for territories to be 12-14 hectares. Summer territories are smaller than winter territories. Along shorelines, the length of a home range ranges from 250-2000 metres, with a width of 50-60 metres.

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 metres from the water's edge. The construction of the burrow is not complex, often consisting of 1-2 passages 8-10 cm in diameter and 1.40-1.50 metres in length, leading to a nest chamber measuring 48 x 55 cm. 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.

Reproduction and development

During the mating season, the sexual organs of the male enlarge greatly and become pinkish-lilac in colour, which is in contrast with the male American mink, whose organs do not change. In the Moscow Zoo
Moscow Zoo
The Moscow Zoo is a zoo founded in 1864 by a group of professor-biologists, K.F. Rulje, S.A. Usov and A.P. Bogdanov, from the Moscow State University. In 1919, the zoo was nationalized. In 1922, the ownership was transferred to the city of Moscow and has remained under Moscow's control ever...

, estrus was observed on 22-26 April, with copulation lasting from 15 minutes to an hour. The average litter consists of 3-7 kits. At birth, kits weigh 6.5 grams, and grow rapidly, trebling their weight 10 days after birth. They are born blind, the eyes opening after 30-31 days. The lactation
Lactation
Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process occurs in all female mammals, however it predates mammals. In humans the process of feeding milk is called breastfeeding or nursing...

 period lasts 2-2.5 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.

Diet

The European mink has a diverse diet consisting largely of aquatic and riparian fauna. There are little differences between its diet and that of the American mink. Vole
Vole
A vole is a small rodent resembling a mouse but with a stouter body, a shorter hairy tail, a slightly rounder head, smaller ears and eyes, and differently formed molars . There are approximately 155 species of voles. They are sometimes known as meadow mice or field mice in North America...

s are the most important food source, closely followed by crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...

s and water insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s. Fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 are an important food source in floodland
Floodland
Floodland is the second album by the British band The Sisters of Mercy, which was released in 1987 and marked their commercial break-through.-Break-up of the original band:...

s, with cases being known of European minks catching fish weighing 1-1.2 kg. The European mink's daily food requirement is 140-180 grams. In times of food abundance, the European mink cache
Cache
In computer engineering, a cache is a component that transparently stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere...

s its food.

Range and status

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. However, over the last 150 years it has severely declined 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.

Decline

The earliest actual records of decreases in European mink numbers occur in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, having already become extinct in several areas by the end of the mid-18th century. A similar pattern occurred in Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

, with no records of mink being published in the 20th century. Records of mink in Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...

 stopped by the late 18th century. By the 1930s-1950s, the European mink became extinct in Poland
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

, Hungary
Hungary
Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...

, Czechoslovakia
Czechoslovakia
Czechoslovakia or Czecho-Slovakia was a sovereign state in Central Europe which existed from October 1918, when it declared its independence from the Austro-Hungarian Empire, until 1992...

 and possibly Bulgaria
Bulgaria
Bulgaria , officially the Republic of Bulgaria , is a parliamentary democracy within a unitary constitutional republic in Southeast Europe. The country borders Romania to the north, Serbia and Macedonia to the west, Greece and Turkey to the south, as well as the Black Sea to the east...

. In Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

, 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
Latvia
Latvia , officially the Republic of Latvia , is a country in the Baltic region of Northern Europe. It is bordered to the north by Estonia , to the south by Lithuania , to the east by the Russian Federation , to the southeast by Belarus and shares maritime borders to the west with Sweden...

, the European mink was thought to be extinct for years, until a specimen was captured in 1992. In Lithuania
Lithuania
Lithuania , officially the Republic of Lithuania is a country in Northern Europe, the biggest of the three Baltic states. It is situated along the southeastern shore of the Baltic Sea, whereby to the west lie Sweden and Denmark...

, the last specimens were caught in 1978-1979. The decline of the European mink in Estonia
Estonia
Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...

 and Belarus
Belarus
Belarus , officially the Republic of Belarus, is a landlocked country in Eastern Europe, bordered clockwise by Russia to the northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Its capital is Minsk; other major cities include Brest, Grodno , Gomel ,...

 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
Ukraine
Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...

 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. European mink numbers in Moldova
Moldova
Moldova , officially the Republic of Moldova is a landlocked state in Eastern Europe, located between Romania to the West and Ukraine to the North, East and South. It declared itself an independent state with the same boundaries as the preceding Moldavian Soviet Socialist Republic in 1991, as part...

 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 Romania
Romania
Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...

n 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 in the Danube Delta
Danube Delta
The Danube Delta is the second largest river delta in Europe, after the Volga Delta, and is the best preserved on the continent. The greater part of the Danube Delta lies in Romania , while its northern part, on the left bank of the Chilia arm, is situated in Ukraine . The approximate surface is...

. In European Russia
European Russia
European Russia refers to the western areas of Russia that lie within Europe, comprising roughly 3,960,000 square kilometres , larger in area than India, and spanning across 40% of Europe. Its eastern border is defined by the Ural Mountains and in the south it is defined by the border with...

, 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 1981-1989, 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
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 and Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

, an isolated range occurs, extending from Brittany
Brittany
Brittany is a cultural and administrative region in the north-west of France. Previously a kingdom and then a duchy, Brittany was united to the Kingdom of France in 1532 as a province. Brittany has also been referred to as Less, Lesser or Little Britain...

 to northern Spain. Data from the 1990s indicate that the European mink has disappeared from the northern half of this previous range.

Habitat loss

Habitat-related declines of European mink numbers may have started during the Little Ice Age
Little Ice Age
The Little Ice Age was a period of cooling that occurred after the Medieval Warm Period . While not a true ice age, the term was introduced into the scientific literature by François E. Matthes in 1939...

, which was further aggravated by human activity. 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
Drainage
Drainage is the natural or artificial removal of surface and sub-surface water from an area. Many agricultural soils need drainage to improve production or to manage water supplies.-Early history:...

 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 decrease and fragmentation, in areas which still maintain suitable river ecosystems like 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.

Overhunting

The European mink was historically hunted extensively, particularly in Russia, where in some districts, the decline prompted a temporary ban on mink hunting in order to let the population recover. In the early 20th century, 40-60,000 European mink were caught annually in the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

, with a record of 75,000 individuals (an estimate which exceeds the modern global European mink population). In Finland, annual mink catches reached up to 3000 specimens in the 1920s. In Romania, 10,000 minks were caught annually around 1960. However, this reason alone cannot account for the decline in areas where hunting was less intensive, such as in Germany.

Decline of crayfish

The decline of European crayfish has been proposed as a factor in the drop in mink numbers, as mink are notably absent in the eastern side of the Urals, where crayfish are also absent. The decline in mink numbers has also been linked to the destruction of crayfish in Finland during the 1920s-1940s, when the crustaceans were infected with crayfish plague
Crayfish plague
Crayfish plague, Aphanomyces astaci, is a water mould that infects crayfish, most notably the European Astacus which dies within a few weeks of being infected...

. The failure of the European mink to expand west to Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...

 coincides with the gap in crayfish distribution.

Competition with the American mink and disease

The American mink
American Mink
The American mink is a semi-aquatic species of Mustelid native to North America, though human intervention has expanded its range to many parts of Europe and South America. Because of this, it is classed as Least Concern by the IUCN. Since the extinction of the sea mink, the American mink is the...

 was introduced and released in Europe during the 1920s-1930s. The American mink is less dependent on wetland habitats than the European mink and is 20-40% larger. The impact of feral American minks on European mink populations has been explained through the competitive exclusion principle
Competitive exclusion principle
In ecology, the competitive exclusion principle, sometimes referred to as Gause's law of competitive exclusion or just Gause's law, is a proposition which states that two species competing for the same resources cannot coexist if other ecological factors are constant...

 and the fact that the American mink reproduces a month earlier than the European species, and matings between male American minks and female European minks result in the embryos being reabsorbed. Thus, female European minks impregnated by male American minks are unable to reproduce with their conspecifics. Disease spread by the American mink can also account for the decline. Though the presence of the American mink has coincided with the decline of European mink numbers in Belarus and Estonia, the decline of the European mink in some areas preceded the introduction of the American mink by many years, and there are areas in Russia where the American species is absent, though European mink populations in these regions are still declining.

Diseases spread by the American mink can also account for the decline. 27 helminth species are recorded to infest the European mink, consisting of 14 trematodes, 2 cestodes and 11 nematode
Nematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...

s. The mink is also vulnerable to pulmonary filariasis
Filariasis
Filariasis is a parasitic disease and is considered an infectious tropical disease, that is caused by thread-like nematodes belonging to the superfamily Filarioidea, also known as "filariae"....

, krenzomatiasis and skrjabingylosis. In the Leningrad
Leningrad Oblast
Leningrad Oblast is a federal subject of Russia . It was established on August 1, 1927, although it was not until 1946 that the oblast's borders had been mostly settled in their present position...

 and Pskov Oblast
Pskov Oblast
Pskov Oblast is a federal subject of Russia . Pskov Oblast borders the countries of Estonia and Latvia, as well as Belarus. It is the westernmost federal subject of contiguous Russia . Its major cities are the administrative center Pskov and Velikiye Luki . Area: 55,300 km²...

s, 77.1% of European minks were found to be infected with skrjabingylosis.

Hybridisation and competition with the European polecat

In the early 20th century, northern Europe underwent a warm climatic period which coincided with an expansion of the range of the European polecat
European polecat
The European polecat , also known as the black or forest polecat , is a species of Mustelid native to western Eurasia and North Africa, which is classed by the IUCN as Least Concern due to its wide range and large numbers. It is of a generally dark brown colour, with a pale underbelly and a dark...

. It has been suggested that the European mink was gradually absorbed by the polecat due to hybridisation. Also, competition with the polecat has greatly increased, due to landscape change favouring the polecat. Also, competition with the polecat has greatly increased, due to landscape change favouring the polecat. There is one record of a polecat attacking a mink and dragging it to its burrow.

Polecat-mink hybrids are termed khor'-tumak by furriers and khonorik by fanciers. Such hybridisation is very rare in the wild, and typically only occurs where European mink are declining. Polecat-mink hybrids have a poorly defined facial mask, have yellow fur on the ears, grey-yellow underfur and long, dark brown guard hairs. They are fairly large, with males attaining the peak sizes known for European polecats (weighing 1,120-1,746 g and measuring 41-47 cm in length) and females being much larger than female European minks (weighing 742 g and measuring 37 cm in length). The majority of polecat-mink hybrids have skulls bearing greater similarities to those of polecats than to minks. Hybrids can swim well like minks and burrow for food like polecats. They are very difficult to tame and breed, as males are sterile, though females are fertile. The first captive polecat-mink hybrid was created in 1978 by Soviet zoologist Dr. Dmitry Ternovsky of Novosibirsk
Novosibirsk
Novosibirsk is the third-largest city in Russia, after Moscow and Saint Petersburg, and the largest city of Siberia, with a population of 1,473,737 . It is the administrative center of Novosibirsk Oblast as well as of the Siberian Federal District...

. 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. Studies on the behavioural ecology of free ranging polecat-mink hybrids in the upper reaches of the Lovat River
Lovat River
The Lovat River is a river in Belarus and Russia. It flows out of Lovatets Lake in northwestern Belarus, and flows north through Pskov and Novgorod Oblasts of Russia into Lake Ilmen. Its main tributaries are the Kunya, Polist, Redya, and Robya Rivers....

 indicate that hybrids will stray from aquatic habitats more readily than pure minks, and will tolerate both parent species entering their territories, though the hybrid's larger size (especially the male's) may deter intrusion. 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. During the winter, their diet overlaps more with that of the polecat, and will eat a larger proportion of rodents than in the summer, though they still rely heavily on frogs and rarely scavenge off of ungulate carcasses as the polecat does.

Predation

Predators of the European mink include the European polecat, the American mink, the golden eagle
Golden Eagle
The Golden Eagle is one of the best known birds of prey in the Northern Hemisphere. Like all eagles, it belongs to the family Accipitridae. Once widespread across the Holarctic, it has disappeared from many of the more heavily populated areas...

, large owl
Owl
Owls are a group of birds that belong to the order Strigiformes, constituting 200 bird of prey species. Most are solitary and nocturnal, with some exceptions . Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish...

s and the red fox
Red Fox
The red fox is the largest of the true foxes, as well as being the most geographically spread member of the Carnivora, being distributed across the entire northern hemisphere from the Arctic Circle to North Africa, Central America, and the steppes of Asia...

. Red fox numbers have increased greatly in areas where the wolf and Eurasian lynx
Eurasian Lynx
The Eurasian lynx is a medium-sized cat native to European and Siberian forests, South Asia and East Asia. It is also known as the European lynx, common lynx, the northern lynx, and the Siberian or Russian lynx...

have been extirpated, as well as areas where modern forestry is practiced. As red foxes are known to prey on mustelids, excessive fox predation on the European mink is a possible factor, though it is improbable to have been a factor in Finland, where fox numbers were low during the early 20th century.

External links

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