The current range consists of few isolated fragments: in northern Spain and western France, in Danube delta in Romania, in the Ukraine and Russia (Maran 2007 and references therein). It occurs from sea level to 1,120 m (Palazón et al. 2003).
The species is still extant in only a minor part of its former range and is in decline even in its currently remaining range enclaves. Only Romania and Vologotsk Region and Arkhangelsk Region can, perhaps, be regarded as exceptions. In Romania, the presence of the European Mink in Danube Delta was confirmed relatively recently (Gotea and Kranz 1999). The European Mink seems to be still widespread there. Repeated live-trapping surveys since 2001 indicate that mink inhabit the area of no more than 2,500 km² (e.g., Kranz et al. 2006). In Vologodsk Region, considering the rapid decline of the species in the neighbouring regions and the presence of the American Mink, it is not likely that the European Mink populations will hold there for long. In the Arkhangelsk Region, the population seems to exist in the northwest of the region, which is close to the northern limit of the range with very low abundance of the species. The presence of the American Mink (Neovison vison) is likely to pose a serious threat to its long-term existence also there (Skumatov 2005, Maran 2007 and references therein).
Mustela lutreola are found in areas of NE Spain and France and throughout Europe to the Irtysh and Ob Rivers. (Wozencraft 1993)
Biogeographic Regions: palearctic (Native )
European mink are medium sized mustelids with a long body, short legs, and short tail. Total length for males is approximately 37.78 cm. Total length of females is 31.5 cm on average. During winter, European mink have a thick, water-repellent undercoat. Fur color is dark brown to black, and the underfur is usually brown. M. lutreola has both white lips and a white chin. Some European minks may have white spots on the throat, chest, and stomach area. (Kruska 1990, Youngman 1990).
Range mass: 440 to 739 g.
Habitat and Ecology
They hunt both in riparian zones and in the water for amphibians, crustaceans (crayfish), fish, small mammals, insects and birds (Sidorovich et al. 1998; Maran et al. 1998; Palazón et al. 2004, 2008). Females become mature for the next breeding season at 11 months (Maran unpublished).
Mustela lutreola thrives in densely shaded banks of fresh water creeks, rivers, and lakes. M. lutreola may construct their own burrows, inhabit an evacuated burrow of a water vole (Arvicola), or may live in crevices among trees roots. (Nowak 1999).
Terrestrial Biomes: forest
Aquatic Biomes: rivers and streams
Life History and Behavior
Status: wild: 10.0 years.
Lifespan, longevity, and ageing
Mating season occurs from February to March. The duration of pregnancy is approximately 35-72 days, with births occurring in April and May. The number of young in a litter is between two and seven, but usually the litter is around four or five. At birth males are approximately 7.39 cm in total length and 8.4 grams and females are 7.19 cm and 7.6 grams. Young are able to open their eyes after 4 weeks and the external auditory meati open within 23 to 27 days. Teeth appear in the young within 15-17 days and are replaced by adult teeth by 60-72 days. Young are weaned at about 10 weeks, and begin tracking and capturing prey. Young begin to disperse at about 2.5 to 4 months. Females are polyestrous and achieve sexual maturity at about 1 year. (Nowak 1999, Youngman 1990)
Average birth mass: 8 g.
Average gestation period: 54 days.
Average number of offspring: 4.
Average age at sexual or reproductive maturity (male)
Sex: male: 323 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 323 days.
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1994Endangered(Groombridge 1994)
- 1990Vulnerable(IUCN 1990)
- 1988Vulnerable(IUCN Conservation Monitoring Centre 1988)
Populations of Mustela lutreola have been in decline for both ecological and commercial reasons. They are now listed as endangered by the IUCN. The primary reason for population declines is commercial trapping for fur. However, M. lutreola also suffers as a result of water pollution and hydroelectric constructions. The introduction of Mustela vison has also negatively impacted M. lutreola populations. A recent study reported that there are approximately 25,000 European minks in Russia, and the world total is less than 30,000. Efforts to introduce M. lutreola in the Kuril Islands and Tajikistan have been initiated. There are also approximately 2,000 M. lutreola found in France and approximately 1,000 in northern Spain. In an attempt to save Mustela lutreola, British and Estonian biologists have established a breeding population on an island in the Baltic Sea.
(Nowak 1990, Zane 1998)
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: endangered
Due to the intensive American Mink control measures during last decade the population in Spain (in Mediterranean basin) is quite stable. Still, remarkable fragmentation has been observed in its range in the north (Basque Country) and the population disappears because of the American Mink. At the same time slight expansion the range to south and south-east has been observed in Aragon in Ebro River basin (Gomez et al. in press).
The overwhelming majority of remaining populations are in decline and of low density. Therefore the size of the species' range leads to overestimation the population status. It is likely that the overall number of mink has declined more than 90% since the beginning of 20th century. Also, the presence of the American Mink in most of range fragments confuses the reports and makes the status projections to the future rather pessimistic.
Some national estimates of population abundance:
- Spain: 500–1,000 individuals (Palazón et al. 2003).
- France: several hundred (S. Aulagnier and R. Libois pers. comm. 2006).
- Danube Delta: since 2003 until 2010 a total of 70 European Mink were life captured in the Romanian part of the delta; trapping success changed dramatically between years, the best year was 2010 with 24 mink captured. Hence for the last decade there are no signs of decline, neither in range nor in number as far as the Romanian part of the Danube Delta and adjacent lagoons in the south are concerned (A. Kranz pers. comm. 2006).
- Belarus: the species is considered to be extinct in former two small range fragments (Sidorovich pers comm. 2011).
- Ukraine: the European Mink was recently re-discovered in Danube and Dniester deltas (de Jongh et al. 2007).
- Russia: in most of the country 61 regions (subcountry units) within the species historical range it is extinct or believed to be extinct (40 regions, 66%). In seven regions that species is known to be extant, and in nine regions is believed still to survive. From those only for 12 regions the European mink is expected to survive for longer than 10 years. The American Mink is now present within the whole remaining range of the European Mink, though may be absent or very low in number in Northern Caucasus and in the north - approximately 64°–66°N, 44°–52°E (near Timanskiy kriazh, to Polar ring).
In the European continent, human activities have resulted in large-scale alteration of landscapes, which has had a substantial impact on various habitats and their species. The European Mink has proved to be sensitive to human-induced environmental change and disturbance. As the type and extent of human influence on the species and its biotope has varied in time and between regions in Europe, also the set of factors contributing to the extinction has varied.
Several factors have often been acting in concert with a cumulative effect. The course of decline during the first half of 20th century in central regions of Russia is a perfect illustration to this. There, the effect of over-exploitation was noticed almost throughout the entire European Mink range (this even resulted in a moratorium of hunting in several regions and even in reinforcement efforts in Jaroslav Region, where around 130 European Mink were translocated with the hope to recover the original, depleted population). In addition, extensive change of habitats in the mid-20th century further contributed to the decline. Thereafter, the invasion of the American Mink posed a very serious threat to the native mink. Large-scale introduction of American Mink in Russia, first planned to be conducted only in regions outside the European Mink's natural range, were ultimately performed also inside the native mink range. The reason for this was twofold: (1) the original mink has become too scarce for the fur-trapping industry, (2) higher value of American Mink fur in the market (Pavlov and Korsakova 1973). It is important to note that in these times the American Mink and European Mink were not regarded by the relevant authorities to be two distinct species. In the course of the introduction operation, 20,400 American Mink were released in the USSR until 1971, with around 4,000 of them being released into the range of the European Mink (Pavlov and Korsakova 1973). The intentional introduction of the alien species was strongly supported by rapidly developing mink fur-farming in the former Soviet Union – escapees from farms formed a continuous source of new founders for introduction. American Mink farming started in the 1920s; in 1972, 1.9 million female American Mink were kept in fur-farms and in 1973, 4.9 million mink were raised in 146 farms in the former Soviet Union (Abramov 1974). As the native mink populations were small and highly fragmented by over-exploitation and habitat loss, the fur-farm escapees, being ecologically more flexible (Maran 1991) easily invaded into the freely available ecological niche, thus making it impossible for the depleted European Mink to recover. Even more, the remaining European Mink groups were an easy target for intra-guild aggression (Maran et al. 1991, 1998; Sidorovich et al. 1999, 2001). The magnitude of the effect of mink farming on the native mink is well illustrated by a recent study in Denmark (a country with a very high number of mink farms), which concludes that 86% of free-living American Mink are escapees from farms (Hammershoj et al. 2005).
Local key factors have changed with time also in many other countries. For instance the impact of over-hunting and/or habitat change weakened the populations and accelerated the impact of the subsequent spread of the American Mink and/or the impact of other factors. It might well be that sometimes the interchange of key factors in time and/or the concurrent impact of several factors has led to a synergistic effect on the European Mink. Further, the time from the introduction of the threat to the extinction of the species can be highly variable, resulting in the so-called extinction or decline lag (Baillie et al. 2004). This, along with the interwoven effect of numerous factors, is likely to result in situations when it is hard or, in some cases, even impossible to identify the actual causes behind the extinction process.
The role of the alien American Mink deserves a special attention. Its role has been noted in several reports as a secondary or not at all important factor, usually emphasizing that the decline of the European Mink started before the invasion of American Mink (Lodé 2002, Lodé et al. 2001, Rozhnov 1992, Schubnikova 1982). Still, there are several records about local extinction of the European Mink concurrent with rapid expansion of the American Mink, e.g., in Estonia, Tver Region in Russia, Basque country (Zadorra river basin and northern Bizkaia) in Spain, Belarus (Cena et al. 2003; Katchanovsky 2002; Maran 1991; Palazón et al. 2002, 2004; Sidorovich 1991, 1993). Further, although there are “time-shot” records on the co-existence of the two mink species, no records demonstrating long-term sympatric coexistence of the two mink species have been traced. Numerous records reveal the local replacement of the European Mink with the American Mink, but no opposite events have been reported. Records on replacement of the European Mink with the American Mink are further supported by studies of behavioural interactions between the two mink species in the wild and well as in experimental conditions. All this evidences that the American Mink has played a special role in the demise of the European Mink. While most of the other agents which have been operating the extinction are relatively easy to stop by conventional conservation management, there is very little one can do to prevent the spread of the alien American Mink. This means that the presence of the American Mink in wide territories across Europe makes the efforts for species recovery a very complicated task.
In addition to the main factors behind the decline of European Mink populations number of other factors may pose local threat the remaining small populations, like hybridization, road casualties, Aleutian disease, secondary poisoning etc.
Habitat loss and degradation is still serious threat especially in western population, both in France and in Spain (mostly in Cantabric rivers).
The following conservation actions are ongoing as of in 2011:
- General: conservation breeding program in the form of European Mink EEP program with about 250 mink in captivity is on-going since 1992. Program is coordinated by Tallinn Zoological Gardens and Foundation Lutreola (Estonia).
- Spain: (a) conservation breeding program since 2004, (b) pilot reinforcement since 2008 in Alava, (c) special program to control American Mink within and around of the European Mink range is on-going, (d) monitoring of European Mink in different autonomous communities as La Rioja (2007 and 2011), Alava (2007, 2009) and Aragon (2008, 2009, 2010, 2012), Navarra 2004-2005, Castilla y León (Burgos 2004, 2010 and Soria 2007, 2010), (e) habitat restoration in Navarra (EU LIFE project), (f) road casualties study in La Rioja (2007), studies on the effect of road casualties, population dynamics.
- France: in 2010 government program for conservation breeding and reintroduction was started for six years.
- Germany: (a) conservation breeding program in Osnabrück managed by Association Euronerz under European mink EEP program, (b) two reintroduction programs: in Saarland and at Steinhuder Meer, Lower Saxony.
- Estonia: (a) establishment of island population in Island Hiiumaa (Dagö) since 2000. At present small core population exists in the islands, but it is not yet viable; (b) studies on reproductive physiology of the species; studies one survival and adaptation of the species in reintroduction programs, studies on genetics, studies on the impact of captive conditions to the stress of mink; (c) regular monitoring of the results of establishment of island population in Hiiumaa.
- Romania: (a) since 2001 regular monitoring has been conducted in Danube delta, (b) in 2011, the strategic plan for European Mink conservation was elaborated in the European Mink handbook for the Danube Delta Biosphere Reserve (Marinov et al. 2011)
Conservation breeding of the species needs all-European coordination so that all single-country initiatives collaborate. Current tendency for isolated one-country breeding efforts will lead to ineffective use of resources and of competence, but also to inability to reach to the captive population size sufficient to maintain genetic diversity in captivity. For remaining in situ populations, the maintenance or restoration of sufficiently large areas of suitable habitats has to be secured by designation of new protected areas and improvement of management of existing protected areas.
The impact of the American mink on local European Mink populations has to be monitored and controlled, and whenever possible and feasible the alien mink populations should be removed. Local authorities have to pay more attention to the effects of the American Mink on the local fauna, including the European Mink. They should support further studies and actions to mitigate the effect of alien mink to the native mink species. For example, intensive control of American Mink is on-going in Spain since 2001. More than 3,000 American Minks have been eradicated around and inside of European Mink distribution area. It is likely that without such a control of alien mink the native mink population in Spain would have vanished already (Gomez and Palazon pers. comm.).
For French and Spanish wild populations which appear to be highly inbred further research needs to be carried out to identify whether these seemingly genetically highly uniform populations suffer from inbreeding depression. The introduction of individuals from ex situ stock from genetically diverse eastern populations has to be considered as a potential conservation measure, if further research confirms the need for this. In addition to genetic studies, comparative studies on ecology and behaviour of the disjunct mink populations (Spanish/French, Romanian and eastern European) should also be conducted to support the findings of genetic studies. The ex situ conservation breeding program has to be enhanced and promoted, as it guarantees the survival of the species in case in situ efforts temporarily fail. It also provides opportunities for the restoration of already vanished wild populations and reinforcement of existing populations whenever needed. Better coordination between different ex situ actions over political borders is needed. Special studies have to be conducted to find the most feasible way how to incorporate the western low-variability populations into the joint program with high-diversity eastern population.
There is also a need for developing an all-European conservation breeding program with secured long-term funding. Further studies are needed about the current the status of the European mink in Romania, Ukraine and elsewhere in eastern part of Europe.
Relevance to Humans and Ecosystems
The European mink (Mustela lutreola), also known as the Russian 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 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 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 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. In Central Europe and Finland, the decline preceded the introduction of the American mink, having likely been due to the destruction of river ecosystems, while in Estonia, the decline seems to coincide with the spread of the American mink.
- 1 Evolution and taxonomy
- 2 Physical description
- 3 Behaviour
- 4 Range and status
- 5 Decline
- 6 References
- 7 External links
Evolution and taxonomy
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 because the species can hybridize.
M. l. lutreola
|Linnaeus, 1758||The pelt is dark, brownish-chestnut or dark brown with a diffuse broad belt on the back. The tail tip is black and the underfur is dark bluish-grey. The overall pelage is long, compact and silky. Adult males measure 365–380 mm (14.4–15 in) in body length and have a tail length of 36–42 mm (1.4–1.7 in) (38% of its body length).||Northern European Russia and Finland||alba (de Sélys Longchamps, 1839)|
alpinus (Ogérien, 1863)
M. l. biedermanni
|Matschie, 1912||France||armorica (Matschie, 1912)|
|M. l. binominata||Ellerman and Morrison-Scott, 1951||caucasica (Novikov, 1939)|
|Middle European mink|
M. l. cylipena
|Matschie, 1912||A very large subspecies, it is only slightly smaller than M. l. turovi. The fur is quite dark and corresponds to the colour of M. l. novikovi. Adult males measure 420–430 mm (17–17 in) in length, while females measure 370–400 mm (15–16 in). Tail length in males is 160 mm (6.3 in), while in females it is 140–180 mm (5.5–7.1 in).||Kaliningrad Oblast, Lithuania, western Latvia, middle Europe except the extreme west (France), Hungary, Romania, former Yugoslavia and Poland||albica (Matschie, 1912)|
budina (Matschie, 1912)
|Middle Russian mink|
M. l. novikovi
|Ellerman and Morrison-Scott, 1951||A moderately sized subspecies, it is slightly larger than M. l. lutreola. It is lighter coloured than M. l. lutreola, being dark tawny or dark brown, with a film of light-reddish highlights. The dark belt on the back is weakly defined or absent. The pelage is overall shorter, less dense and less silky than M. l. lutreola. Adult males measure 360–420 mm (14–17 in) in body length.||Middle zone of the European part of the former Soviet Union (Estonia, eastern Latvia, Belarus, eastern Ukraine, lower Don and Volga regions||borealis (Novikov, 1939)|
Mustela l. transsylvanica
|Éhik, 1932||Smaller than M. l. turovi, with dark-tawny fur||Moldavia, Romania, Hungary, Bulgaria and former Yugoslavia||ehiki (Kretzoi, 1942)|
hungarica (Éhik, 1932)
M. l. turovi
|Kuznetsov in Novikov, 1939||A large-sized subspecies, it has quite long, but sparse and coarse pelage and less compact underfur. The fur is light-tawny or light-brown with clear rusty highlights. The underfur is light bluish-grey. White chest marks are much more frequent in this subspecies than in others. The ends of the limbs are often white. Adult males usually measure more than 42 cm (17 in) long.||Caucasus, lower Volga and lower Don regions, probably eastern Ukraine|
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. 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 arches and has a less massive facial region. In general characteristics, the skull is intermediate in shape between that of the Siberian weasel and the European polecat. Overall, the skull is less specialised for carnivory than that of polecats and the American mink. Males measure 373–430 mm (14.7–17 in) in body length, while females measure 352–400 mm (13.9–16 in). Tail length is 153–190 mm (6.0–7.5 in) in males and 150–180 mm (5.9–7.1 in). Overall weight is 550–800 grams (1.21–1.8 lb). It is a fast and agile animal, which swims and dives skilfully. It is able to run along stream beds, and stay underwater for one to two minutes. When swimming, it paddles with both its front and back limbs simultaneously.
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. The length of the hairs on the back and belly differ little, a further adaptation to the European mink's semiaquatic 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 albinos 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, but with 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 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 (270–2,200 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 (6.6–11 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 × 55 cm (19 × 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.
Reproduction and development
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 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.
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. 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, efforts have been made to re-establish viable populations on the islands of Saaremaa and Hiiumaa.
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 1978-1979. 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.
Possible reasons for decline
Habitat-related declines of European mink numbers may have started during the Little Ice Age, 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 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.
The European mink was historically hunted extensively, particularly in Russia, where in some districts, the decline prompted a temporary ban on mink hunting to let the population recover. In the early 20th century, 40-60,000 European minks were caught annually in the Soviet Union, with a record of 75,000 individuals (an estimate which exceeds the modern global European mink population). In Finland, annual mink catches reached 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 intense, 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 minks 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. The failure of the European mink to expand west to Scandinavia coincides with the gap in crayfish distribution.
Competition with the American mink and disease
The American mink 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 and because 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. Twenty-seven helminth species are recorded to infest the European mink, consisting of 14 trematodes, two cestodes and 11 nematodes. The mink is also vulnerable to pulmonary filariasis, krenzomatiasis and skrjabingylosis. In the Leningrad and Pskov Oblasts, 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. The European mink possibly was gradually absorbed by the polecat due to hybridisation. 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 minks are declining. 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 (2.47–3.849 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). 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. 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 indicate the 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 diets overlap more with those of polecats, and will eat a larger proportion of rodents than in the summer, though they still rely heavily on frogs and rarely scavenge ungulate carcasses as the polecat does.
Predators of the European mink include the European polecat, the American mink, the golden eagle, large owls and the red fox. Red fox numbers have increased greatly in areas where the wolf and Eurasian lynx have been extirpated, as well as areas where modern forestry is practised. 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.
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