European mink Mustela lutreola – a native species that urgently needs protection

Poland has become an important refuge for several charismatic species, at one point extinct in the wild here. We are talking not only about the European bison and Baltic sturgeon, but also about the moose, beaver and cephalopod. Another faunal gem worth restoring to our nature is the European mink (“otter”) Mustela lutreola. Few Europeans realize how common and economically important it was in centuries past. And how close it is today to irreversible extinction.

The just-established Lower Oder Valley National Park could become the next reintroduction site for this critically endangered mammal. Scientists and activists from the University of Szczecin/Pol. Tow. Conservation Genetics LUTREOLA, especially Dr. J. Skorupski, have been working on its return for years. They sequenced her genome as leaders of an international consortium. Rewilding Oder Delta e.V. is in favor! [2, 7, 8, 9, 11, 13]

European mink – a species on the verge of extinction

It is widely believed that the European mink became extinct almost everywhere for two reasons: overharvesting and competition with the American mink ( vison) Neogale vison. Vison breeders point to a number of uncertainties about the mechanisms and dates of our M. lutreola’s disappearance. They also prove the innocence of specimens escaped from their breeding, while admitting that some other American mink populations may have been at fault. Nevertheless, active protection of our mink almost always means mass extermination or trapping of their American cousins [1, 2].

Analysis of past work points to a number of further mechanisms for the disappearance of “otter”, which include:

1. The presence of the vison (American mink) – competition and more;
2. habitat loss;
3. overfishing;
4. The extinction of Europe’s native crayfish;
5. expansion of the common polecat;
6. An increase in fox activity;
7. Restoration of great owl and eagle populations;
8. The temporary extinction of the beaver;
9. extermination as a polecat or otter [1, 2, 4, 7, 11].

It is worth devoting a few extra sentences to each of them.

Presence of vison (American mink)

The ecological niches of similar, related species usually overlap quite a bit. Hence, competition between them is sometimes fierce and can lead to either niche separation or extinction of the weaker species in a given area. For decades, the debate has not been silent as to whether the visons occupied the abandoned ecological niches after the extinction of the European mink a few decades earlier or whether they killed off the sparse populations of M. lutreola with their competition. Let’s not forget that the presence of American mink meant more than just direct competition with our species. It also meant new diseases and parasites brought from North America and attempts at hybridization, in this case leading to increased mortality of M. lutreola females due to perinatal complications after fertilization by Neogale vison males .

American and European mink are undoubtedly different species and even genera: Mustela (which also includes polecats, ferrets, ermine and weasels)and Neogale (which includes several species from the Western Hemisphere, including one extirpated in the 19th century). Therefore, their co-occurrence did not result in a swarm of hybrids, fertile as in the case of wildcat and domestic cat, or infertile as in the hybridization of various trout [1,2,7].

Habitat loss

Interference with and destruction of natural habitats in this case meant regulating small rivers and draining the wet forests developing over them. Add to this the end of the Little Ice Age, the steppification of many regions of Europe and urbanization [4].

Overfishing

This is an obvious candidate for the main culprit of today’s quantitative state of the “otter”. Hunters do not always act rationally, and contrary to the well-known opinions of Herodotus, Plato, etc. this applies not only to Homo sapiens. The first to die are the victims on islands. However, this applies not only to islands in the literal sense, but also in the broader interpretation of McArthur and Wilson’s “environmental islands.” The detached, island nomen omen positions of M. lutreola fit the latter’s definition. During the New Economic Policy of 1921-28, it was reported that the USSR was harvesting 40-60,000. specimens per year, thus much higher than the current total of all wild and farmed specimens combined. Harvests in Romania in the 1960s were equally high. In the 1970s. [1, 4]

Extinction of Europe’s native crayfish

European crayfish were an important part of M. lutreola‘s diet. When they were affected by industrial contamination of rivers in the 19th century, and later by the crayfish plague, they were replaced by species from across the Great Water. Therefore, today the presence of these crustaceans does not at all prove the extraordinary cleanliness of the water. Scientists have long noted that the European mink has never reached where the “cobbler” (river crayfish) and “tailor” (river crayfish) do not reach, that is, east of the Urals and in some areas of Karelia. Also, the mass extinction of crayfish that continued in Finland from the 1920s to the 1940s coincided with the rapid decline of the European mink [4].

Expansion of the common polecat Mustela putorius

The warming of the climate in the 20th century. caused the range of the common polecat to shift prominently northward. The last wild European mink may therefore have dissolved into the gene pool of the polecat, rather than the distantly related American mink. Hybrids between M. putorius and M. lutreola have been observed for a long time: hunters called them chor-tumaks, and furry people called them chonorics. They are characterized by a coloration intermediate between both parental species: a faint mask, yellowish ears and long, dark brown guard hairs. They swim as well as mink, and they burrow their own and penetrate others’ burrows as efficiently as polecats.

In summer, their diet is more like that of mink, i.e. consisting mainly of frogs; in winter, rather like that of the polecat, i.e. with a predominance of rodents. Males will always be infertile, at least as large as polecats, and females will be poorly fertile. In the Soviet Union, they have been created deliberately since the late 1970s. In the 1970s. For the purpose of obtaining fur. Over time, however, this has become unfeasible due to the lack of new European mink for crossbreeding. Hybridization in the wild has increased wherever M. lutreola has declined [1, 4, 6, 12]. There are no records of mink interactions with the steppe polecat M. eversmanni. However, such interactions cannot be ruled out also in places where the two species may have come into contact, for example, in the Lublin region.

Increase in fox activity

The fox was one of the most important natural enemies of the “otter.” The numbers and activity of the “mycita” increased significantly after the extirpation of the wolf and lynx, changes in poultry breeding (the disappearance of truly free range, where poultry grazed close to forests), and finally the inclusion of this red-headed canine in health care programs (rabies vaccine drops) [4].

Recovery of great owl and eagle populations

European mink have fallen prey to some of the Old World’s most magnificent owls and raptors. The gradual recovery of golden eagle, bald eagle and/or eagle owl populations may have killed some relict populations of this species [1,4].

The temporary extinction of the beaver

European mink, like muskrats today, lived not only in burrows, but also in feeding grounds and beaver dams. The disappearance of these largest rodents of Eurasia began as early as the Middle Ages. It cannot be ruled out that the absence of the “beaver-developer” in the 17th-20th centuries. translated into the extinction of their weasel-like sub-occupant [10]. Note that a similar crisis affected many secondary hollows in Europe after only the woodpeckers disappeared. In turn, the absence of gophers, or more precisely their burrowing owls, translated into the extinction of Poland’s largest steppe bumblebees: the giant, steppe and dorsal bumblebee.

Extermination of M. putorius and the otter Lutra lutra as a common polecat

Cowards, as the name suggests, have never enjoyed the sympathy of humans. Their merits in the fight against rats and mice were underestimated. They were fiercely exterminated as a threat to poultry, pheasants, rabbits or nutria. The valuable fur was an added bonus. To this day, they are allowed to be hunted year-round in places where grouse or black grouse are protected, as well as in places where partridges, pheasants and hares reside. The otter has been given protection (under the Habitat Directive, often also as a species, e.g.: in Poland), as it was previously heavily depleted as a fishing pest. Therefore, it cannot be ruled out that the European mink fell prey to the fight against the polecat and the otter [10].

Let’s learn from others’ mistakes

The restoration of the Polish-German population of European mink on the Oder River can benefit from American experience on the restoration of the black-headed polecat Mustela nigripes. In 1996, the last wild specimens in the US died. Slightly earlier, in 1987, at most 18 specimens held in captivity were counted, in Wyoming. It’s worth collecting European mink sperm and oocytes in advance, taking advantage of the fact that mammalian ova and embryos are easier to store alive than, say, fish or frog oocytes.

On the other hand, the quality of sperm in male minks and polecats kept in captivity declines in each generation. Starting in 2020. cloning of black-tailed polecats is underway. The sustainability of reintroduced populations is hard to maintain when they are simultaneously deprived of their food base as part of the fight against prairie dogs [3, 5]. It’s a tip for us to precede the introduction of European mink with the restoration of populations of crayfish, fish and amphibians, groups particularly affected by golden algae blooms.

In the article, I used, among other things. z:

1. Heptner, V. G., Sludskii, A. A. (2002). Mammals of the Soviet Union. Vol. II, part 1b, Carnivores(Mustelidae and Procyonidae). Smithsonian Institution Libraries and National Science Foundation, Washington, D.C.
2. Karáth, K. (2017). Scientists think they can save the European mink – by killing its ruthless rivals. Science https://www.science.org/content/article/scientists-think-they-can-save-european-mink-killing-its-ruthless-rivals [16 .05.2024].
3. Macdonald, D. (1992). The Velvet Claw: A Natural History of the Carnivores. Parkwest, New York.
4. Maran, T., Henttonen, H. (1995). Why is the European mink, Mustela lutreola disappearing? – A review of the process and hypotheses. Annales Fennici Zoologici 32: 47-54.
5. Santymire, R., Lonsdorf, E.,…Kreeger, J., Howard, J. (2019). Inbreeding causes decreased seminal quality affecting pregnancy and litter size in the endangered black-footed ferret. Animal Conservation 22 (4): 331-340.
6. Sidorovich, V. (2001) Finding on the ecology of hybrids between the European mink Mustela lutreola and polecat M. putorius at the Lovat upper reaches, NE Belarus . Small Carnivore Conservation 24: 1-5.
7. Skorupski, J. (2016). Nature conservation and invasion of the American mink(Neovison vison) in Poland-a critical analysis. Sylvan, 160(1), 79-87.
8. Skorupski, J. (2022). Characterisation of the complete mitochondrial genome of critically endangered Mustela lutreola (Carnivora: Mustelidae) and its phylogenetic and conservation implications. Genes, 13(1), 125.
9. Skorupski, J., Brandes, F., Seebass, C., Festl, W., Smietana, P., Balacco, J., … & Jarvis, E. D. (2023). Prioritizing Endangered Species in Genome Sequencing: Conservation Genomics in Action with the First Platinum-Standard Reference-Quality Genome of the Critically Endangered European Mink Mustela lutreola L., 1761. International Journal of Molecular Sciences, 24(19), 14816.
10. Sommer, R., & Benecke, N. (2004). Late-and Post-Glacial history of the Mustelidae in Europe. Mammal Review, 34(4), 249-284.
11. Suminski, P., Goszczyński, J., Romanowski, J. (1993). Mammals of prey of Europe. PWRiL, Warsaw.
12. Tumanov, I. L. & Abramov, A. V. (2002) A study of the hybrids between the European Mink Mustela lutreola and the Polecat M. putorius. Small Carnivore Conservation 27: 29-31.
13. https://lutreola.pl/aktualnosci/1/31-szy-marca–dzien-norki-europejskiej/ [17 .05.2024]