Least weasel

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Least weasel
Temporal range: Late Pleistocene – Recent
Least weasel at the British Wildlife Centre, Surrey, England

Least Concern  (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Mustelidae
Genus: Mustela
Species:
M. nivalis
Binomial name
Mustela nivalis
Global range of the least weasel

The least weasel (Mustela nivalis), little weasel, common weasel, or simply weasel is the smallest member of the

IUCN, due to its wide distribution and large population throughout the Northern Hemisphere.[1]

The least weasel varies greatly in size over its range. The body is slender and elongated, and the legs and tail are relatively short. The colour varies geographically, as does the

pelage
type and length of tail. The dorsal surface, flanks, limbs and tail of the animal are usually some shade of brown while the underparts are white. The line delineating the boundary between the two colours is usually straight. At high altitudes and in the northern part of its range, the coat becomes pure white in winter. Eighteen subspecies are recognised.

Small rodents form the largest part of the least weasel's diet, but it also kills and eats rabbits, other mammals, and occasionally birds, birds' eggs, fish and frogs. Males mark their territories with olfactory signals and have exclusive home ranges which may intersect with or include several female ranges. Least weasels use pre-existing holes to sleep, store food and raise their young. Breeding takes place in the spring and summer, and there is a single litter of about six kits which are reared exclusively by the female. Due to its small size and fierce nature, the least weasel plays an important part in the mythology and legend of various cultures.

Taxonomy and evolution

The least weasel was given its scientific name Mustela nivalis by Carl Linnaeus in his

type locality was Västerbotten in Sweden.[3]: 1  As an animal with a very wide distribution, the morphology of the least weasel varies geographically. The species was reviewed by Reichstein in 1957 and again by van Zyll de Jong in 1992 and Reig in 1997. Youngman (1982) placed it in the subgenus Mustela while Abramov (1999) considered it should be included in the subgenus Gale. Based on skull characteristics, Reig (1997) proposed that the taxon should be split into four species, M. subpalmata, M. rixosa, M. vulgaris and M. eskimo. Abrimov and Baryshinikov (2000) disagreed, recognising only M. subpalmata (the Egyptian weasel) as a separate species.[4] However, Rodrigues et al. (2016) recognized M. subpalmata as a distinct population of nivalis rather than a distinct species.[5]

Within the genus Mustela, the least weasel is a relatively unspecialised form, as evidenced by its

Bering land bridge 200,000 years ago.[8]

Subspecies

The least weasel has a high geographic variation, a fact which has historically led to numerous disagreements among biologists studying its systematics. The least weasel's subspecies are divided into three categories:[9]

Subspecies Trinomial authority Description Range Synonyms
Common least weasel
M. n. nivalis

(

Nominate subspecies
)

Linnaeus, 1766 A medium-sized subspecies with a tail of moderate length, constituting about 20–21% of its body length. In its summer fur, the upper body is a dark brownish or chestnut colour, while its winter fur is pure white. It is probably a transitional form between the small pygmaea and the large vulgaris.[10] The middle regions of
Hokkaidō
. 		caraftensis (Kishida, 1936)

kerulenica (Bannikov, 1952)
punctata (Domaniewski, 1926)
yesoidsuna (Kishida, 1936)

Allegheny least weasel
M. n. allegheniensis 		Rhoads, 1901 Similar to M. n. rixosa, but is larger, has a broad skull and darker coat, and is more adapted to live in deciduous forests[11] The northeastern United States (Michigan, Pennsylvania, New York, Virginia, North Carolina, Ohio, Illinois, Wisconsin, West Virginia, and Indiana)
Transcaucasian least weasel
M. n. boccamela

Bechstein, 1800 A very large subspecies, with a long tail constituting about 30% of its body length. In its summer fur, the upper body is light brownish or chestnut with yellowish or reddish tints, with some individuals having a brownish dot on the corners of the mouth and sometimes on the chest and belly. The winter fur is not pure white, being usually dirty white with brown patches.[12]
Asia Minor and probably western Iran
 italicus (Barrett-Hamilton, 1900)
Plains least weasel
M. n. campestris 		Jackson, 1913 The Great Plains of the United States (South Dakota, Iowa, Nebraska, and Kansas)
Caucasian least weasel
M. n. caucasica 		Barrett-Hamilton, 1900 dinniki (Satunin, 1907)
Alaskan least weasel
M. n. eskimo 		Stone, 1900 A small subspecies. Resembles M. n. rixosa, but has a duller colour, a larger skull and a shorter tail.[13] Alaska, the Yukon, and the Northwest Territories
Turkmenian least weasel
M. n. heptneri 		Morozova-Turova, 1953 A very large subspecies with a long tail constituting about 25–30% of its body length. In its summer fur, the upper body is very light sandy brown or pale-yellowish. The fur is short, sparse and coarse, and does not turn white in winter.[14] The deserts and semi-deserts of southern
Koppet Dag, Afghanistan and northeastern Iran
Japanese least weasel
M. n. namiyei 		Kuroda, 1921 Smaller than M. n. rixosa and paler than M. n. eskimo. Resembles M. n. pygmaea, but the head and body are longer and the tail considerably longer.[15] Northern
Honshū (Aomori, Akita and Iwate
Prefectures)
Mediterranean least weasel
M. n. numidica

Pucheran, 1855 The largest subspecies
Azores Islands and Corsica
 albipes (Mina Palumbo, 1868)

algiricus (Thomas, 1895)
atlas (Barrett-Hamilton, 1904)
corsicanus (Cavazza, 1908)
fulva (Mina Palumbo, 1908)
galanthias (Bate, 1905)
ibericus (Barrett-Hamilton, 1900)
meridionalis (Costa, 1869)
siculus (Barrett-Hamilton, 1900) subpalmata Hemprich & Ehrenberg, 1833

Montane Turkestan least weasel
M. n. pallida 		Barrett-Hamilton, 1900 A medium-sized subspecies with a tail constituting about 24% of its body length. The colour of the summer fur is light-brownish, while the winter fur is white.[16] The montane parts of
Hindukush
Siberian least weasel
M. n. pygmaea 		J. A. Allen, 1903 A very small subspecies, with a short tail which constitutes about 13% of its body length. In its summer coat, the dorsal colour is dark brown or reddish, while the winter fur is entirely white.[17] All of
Korean Peninsula; all of Mongolia (except for the eastern part), and probably northeastern China
 kamtschatica (Dybowksi, 1922)
Bangs' least weasel
M. n. rixosa

Bangs, 1896 The smallest subspecies and the smallest living mammalian carnivore in the world. In its summer coat, the fur is dark reddish-brown, while the winter fur is pure white.[18] Nunavut, Labrador, Quebec, Minnesota, North Dakota, Montana, Saskatchewan, Alberta, and British Columbia
Middle European least weasel
M. n. vulgaris 		Erxleben, 1777 A somewhat larger subspecies than nivalis with a longer tail, which constitutes about 27% of its body length. In its summer fur, the upper body varies from being light brownish to dark chestnut, while the winter fur is white in its northern range and piebald in its southern range.[19] Southern European Russia from the latitude of southern Voronezh and Kursk districts,
Ciscaucasia, and the northern slopes of the main Caucasus, eastward to the Volga. Outside the former Soviet Union, its range includes Europe southward to the Alps and the Pyrenees. Introduced to New Zealand.[20][21]
 dumbrowskii (Matschie, 1901)

hungarica (Vásárhelyi, 1942)
minutus (Pomel, 1853)
monticola (Cavazza, 1908)
nikolskii (Semenov, 1899)
occidentalis (Kratochvil, 1977)
trettaui (Kleinschmidt, 1937)
vasarhelyi (Kretzoi, 1942)

Description

Skull of a least weasel
Least weasel at the British Wildlife Centre
Skulls of a long-tailed weasel (top), a stoat (bottom left) and least weasel (bottom right), as illustrated in Merriam's Synopsis of the Weasels of North America

The least weasel has a thin, greatly elongated and extremely flexible body with a small, yet elongated, blunt-muzzled head which is no thicker than the neck. The eyes are small in relation to their head size and are bulging and dark colored. The legs and tail are relatively short, the latter constituting less than half the body length. The feet have sharp, dark-coloured claws, and the

cranium and shortened facial region.[24] The skull is, overall, similar to that of the stoat, but smaller, though the skulls of large male weasels tend to overlap in size with those of small female stoats.[25]
There are usually four pairs of nipples but these are only visible in females.

The weasel has a stronger bite force than a lion, tiger, hyena, or even a bear, relative to body size. A combination of shorter jaws, powerful muscles, and the placement of its teeth allows the weasel to have tremendous power when it snaps its jaws shut.[26]

The baculum is short, 16 to 20 mm (0.6 to 0.8 in), with a thick, straight shaft. Fat is deposited along the spine, kidneys, gut mesentries and around the limbs. The least weasel has muscular anal glands under the tail, which measure 7 by 5 mm (0.3 by 0.2 in), and contain sulphurous volatiles, including thietanes and dithiacyclopentanes. The smell and chemical composition of these chemicals are distinct from those of the stoat.[25] The least weasel moves by jumping, the distance between the tracks of the fore and hind limbs being 18 to 35 cm (7 to 14 in).[27]

Skeleton, as illustrated in Lydekker's The New Natural History

Dimensions vary geographically, to an extent rarely found among other mammals. Least weasels of the boccamela group, for example, may outweigh the smaller races by almost four times. In some large subspecies, the male may be 1.5 times longer than the female. Variations in tail length are also variable, constituting 13 to 30 percent of the length of the body. Average body length in males is 130 to 260 mm (5 to 10 in), while females average 114 to 204 mm (4.5 to 8.0 in). The tail measures 12 to 87 mm (0.5 to 3.4 in) in males and 17 to 60 mm (0.7 to 2.4 in) in females. Males weigh 36 to 250 g (1.3 to 8.8 oz), while females weigh 29 to 117 g (1.0 to 4.1 oz).[28]

The winter coat is conspicuous when there is no snow on the ground

The winter fur is dense, but short and closely fitting. In northern subspecies, the fur is soft and silky, but coarse in southern forms. The summer fur is very short, sparser and rougher. The upper parts in the summer fur are dark, but vary geographically from dark-tawny or dark-chocolate to light pale tawny or sandy. The lower parts, including the lower jaw and inner sides of the legs, are white. There is often a brown spot at the corner of the mouth. The dividing line between the dark upper and light lower parts is usually straight but sometimes forms an irregular line. The tail is brown, and sometimes the tip is a little darker but it is never black. In the northern part of its range and at high altitudes, the least weasel changes colour in the winter, the coat becoming pure white and exhibiting a few black hairs in rare circumstances.[24][29]

Fossil record

Fossilised remains of the least weasel are known from Denisova Cave.[30]

Behaviour and ecology

Reproduction and development

The least weasel mates in April–July and there is a 34- to 37-day

fecund in February–October, though the early stages of spermatogenesis do occur throughout the winter months. Anestrus in females lasts from September until February.[31]

The female raises its kits without help from the male. They are 1.5 to 4.5 g (0.05 to 0.16 oz) in weight at birth. Newborn kits are born pink, naked, blind and deaf, but gain a white coat of downy fur at the age of 4 days. At 10 days, the margin between the dark upper parts and light under parts becomes visible. The

milk teeth erupt at 2 to 3 weeks of age, at which point the young start to eat solid food, though lactation can last 12 weeks. The eyes and ears open at 3 to 4 weeks of age, and by 8 weeks, killing behaviour is developed. The family breaks up after 9 to 12 weeks.[31] There is a single litter each year and least weasels can live for 7 or 8 years.[29]

Territorial and social behaviours

Two least weasels fighting

The least weasel has a typical mustelid territorial pattern, consisting of exclusive male ranges encompassing multiple female ranges. The population density of each territory depends greatly on food supply and reproductive success, thus the social structure and population density of any given territory is unstable and flexible.

faeces, urine and anal and dermal gland secretions, the latter two of which are deposited by anal dragging and body rubbing. The least weasel does not dig its own den, but nests in the abandoned burrow of another species such as a mole or rat.[33] The burrow entrance measures about 2.5 cm (0.98 in) across and leads to the nest chamber located up to 15 cm (5.9 in) below ground. The nest chamber (which is used for sleeping, rearing kits and storing food) measures 10 cm (3.9 in) in diameter, and is lined with straw and the skins of the weasel's prey.[34]

The least weasel has four basic vocalisations; a guttural hiss emitted when alarmed, which is interspersed with short screaming barks and shrieks when provoked. When defensive, it emits a shrill wail or squeal. During encounters between males and females or between a mother and kits, the least weasel emits a high-pitched trilling. The least weasel's way of expressing aggression is similar to that of the stoat. Dominant weasels exhibit lunges and shrieks during aggressive encounters, while subdominant weasels will emit submissive squeals.[33]

Diet

Taxidermy exhibit showing a least weasel attacking a European hare, in the Natural History Museum of Genoa

The least weasel feeds predominantly on

field vole (Microtus agrestis). These have fluctuations in population size, and in years of abundance may form up to 54% of the weasel's diet. In years of scarcity, birds form a greater proportion of the diet and female least weasels may fail to breed.[36]

Despite its small size, the least weasel is a fierce hunter, capable of killing a rabbit five to 10 times its own weight.[37] Although they are commonly taken, the rabbits are usually young specimens, and become an important food source during the spring, when small rodents are scarce and rabbit kits are plentiful. Male least weasels take a higher proportion of rabbits than females, as well as an overall greater variety of prey. This is linked to the fact that being larger, and having vaster territorial ranges than females, males have more opportunities to hunt a greater diversity of prey.[38]

The least weasel forages undercover, to avoid being seen by foxes and birds of prey. It is adapted for pursuing its prey down tunnels, though it may also bolt prey from a burrow and kill it in the open.

blood loss or circulatory shock.[38] When food is abundant, only a small portion of the prey is eaten, usually the brain. The average daily food intake is 35 g (1 oz), which is equivalent to 30–35% of the animal's body weight.[35]

Predators and competitors

Least weasels driven from a mountain hare carcass by a stoat, as illustrated in Barrett-Hamilton's A History of British Mammals

The least weasel is small enough to be preyed upon by a range of other predators.

copperhead.[34] Aside from its smaller size, the least weasel is more vulnerable to predation than the stoat because it lacks a black predator deflection mark on the tail.[39]

In areas where the least weasel is sympatric with the stoat, the two species compete with each other for rodent prey. The weasel manages to avoid too much competition by living in more upland areas, feeding on smaller prey and being capable of entering smaller holes. It actively avoids encounters with stoats, though female weasels are less likely to stop foraging in the presence of stoats, perhaps because their smaller size allows them to quickly escape into holes.[41]

Diseases and parasites

Ectoparasites known to infest weasels include the louse Trichodectes mustelae and the mites Demodex and Psoregates mustela. The species may catch fleas from the nests and burrows of its prey. Flea species known to infest weasels include Ctenophthalmus bisoctodentatus and Palaeopsylla m. minor, which they get from moles, P. s. soricis, which they get from shrews, Nosopsyllus fasciatus, which they get from rodents and Dasypsyllus gallinulae which they get from birds.[39]

Taenia.[39] Least weasels are commonly infected with the nematode Skrjabingylus nasicola, adults of which are found in the nasal sinuses and can damage the skull. There is no evidence that this has serious detrimental effects on even heavily infested animals.[42]

Distribution and habitat

Alaskan least weasel (M. n. eskimo)

The least weasel has a

Mediterranean islands.[43] It also occurs on Honshu and Hokkaido Islands in Japan and on Kunashir, Iturup, and Sakhalin Islands in Russia.[1]

The least weasel occupies a similar type of habitat as the stoat, but it frequents wet places less often. It can be found in fields, open woodland, bushy or rocky areas, parks and gardens, and at altitudes of up to about 3,000 metres (9,800 ft).[29]

Conservation status

The least weasel has a very wide circumboreal range and a large total population and is therefore listed by the

least concern". Its chosen habitat is in areas of coarse vegetation and in some regions its numbers may be decreasing because of changes in agricultural practices, but altogether its population trend is thought to be steady. It is relatively common in Eurasia but less abundant in North America and is thought to be rare in the southeastern United States. It is subject to considerable variations in numbers in areas where its main rodent prey is liable to large population fluctuations. In years of rodent population booms, the least weasel numbers may rise by up to ten-fold, only to slump again as prey becomes scarce again in the following years.[1]

In folklore and mythology

Macedonian and Greek culture

17th century print of a least weasel confronting a basilisk

The

Macedon, women who suffered from headaches after having washed their heads in water drawn overnight would assume that a weasel had previously used the water as a mirror, but they would refrain from mentioning the animal's name for fear that it would destroy their clothes.[citation needed
]

Similarly, a popular superstition in southern Greece had it that the least weasel had previously been a bride, who was transformed into a bitter animal which would destroy the wedding dresses of other brides out of jealousy.[44] According to Pliny the Elder, the least weasel was the only animal that was capable of killing the basilisk:

To this dreadful monster the effluvium of the weasel is fatal, a thing that has been tried with success, for kings have often desired to see its body when killed; so true is it that it has pleased Nature that there should be nothing without its antidote. The animal is thrown into the hole of the basilisk, which is easily known from the soil around it being infected. The weasel destroys the basilisk by its odour, but dies itself in this struggle of nature against its own self.[45]

Ojibwe and Inuit culture

The Ojibwe believed that the least weasel could kill the dreaded wendigo by rushing up its anus.[46]

In

Inuit mythology, the least weasel is credited with both great wisdom and courage, and whenever a mythical Inuit hero wished to accomplish a valorous task, he would generally change himself into a least weasel.[47]

See also

References

Citations

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  6. ^ Heptner & Sludskii 2002, p. 972
  7. ^ Kurtén 1968, pp. 102–103
  8. ^ Macdonald 1992, p. 205
  9. ^ a b c d Heptner & Sludskii 2002, pp. 975–978
  10. ^ Heptner & Sludskii 2002, p. 982
  11. JSTOR 4062685
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  12. ^ Heptner & Sludskii 2002, p. 980
  13. JSTOR 1373581
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  14. ^ Heptner & Sludskii 2002, p. 981
  15. JSTOR 1373554
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  16. ^ Heptner & Sludskii 2002, p. 984
  17. ^ Heptner & Sludskii 2002, p. 978
  18. ^ Merriam 1896, pp. 14–15
  19. ^ Heptner & Sludskii 2002, p. 983
  20. ^
    ISBN 9780643099166
  21. ISBN 0-19-558477-5
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  22. ^ Fergus, Chuck. "Weasels" (PDF). Pennsylvania Game Commission. Retrieved 8 November 2017.
  23. ^ Heptner & Sludskii 2002, pp. 967–969
  24. ^ a b Heptner & Sludskii 2002, p. 969
  25. ^ a b Harris & Yalden 2008, p. 468
  26. ^ "The Most Powerful Bite | Weasels: Feisty & Fearless | BBC Earth". YouTube.
  27. ^ Heptner & Sludskii 2002, p. 991
  28. ^ Heptner & Sludskii 2002, pp. 970–972
  29. ^
    ISBN 978-0-00-212080-7
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  30. doi:10.1016/j.quaint.2020.08.038
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  31. ^ a b Harris & Yalden 2008, p. 474
  32. JSTOR 3543948
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  33. ^ a b Harris & Yalden 2008, pp. 471–472
  34. ^ a b Merritt & Matinko 1987, p. 277
  35. ^ a b c Heptner & Sludskii 2002, pp. 987–988
  36. JSTOR 4182
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  37. ^ Macdonald 1992, p. 208
  38. ^ a b c Harris & Yalden 2008, pp. 472–473
  39. ^ a b c d Harris & Yalden 2008, p. 475
  40. ^ Heptner & Sludskii 2002, p. 992
  41. ^ Harris & Yalden 2008, p. 469
  42. doi:10.1111/j.1469-7998.1977.tb04157.x
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  43. S2CID 20057808
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  44. ^ Abbott, G. A. (1903), Macedonian Folklore, pp. 108–109, Cambridge University Press
  45. ^ Pliny the Elder (1855). John Bostock; Henry Thomas Riley (eds.). "The Natural History". Retrieved 23 August 2022.
  46. ISBN 0-299-07314-9
  47. ISBN 1-4179-8416-3

General and cited references

Further reading

External links

Look up least weasel in Wiktionary, the free dictionary.
Wikimedia Commons has media related to Mustela nivalis.
Wikispecies has information related to Mustela nivalis.
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