Living Organisms / Animalia / Craniata / Mammalia / Carnivora / Mustelidae / Mustela / Species
Mustela erminea - Stoat (Click photographs/illustrations: full picture & further details)
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General and References

Alternative Names (Synonyms)

  • Ermine
  • Short-tailed weasel
  • Whittrel (Scotland)
  • Weasel (Ireland)
  • Hermine (French)
  • Hermelin (German)
  • Gro▀wiesel (German)

Alternative species names (the second part of the binomial species names): [Genus] alascensis; [Genus] algiricus; [Genus] anguinae; [Genus] angustidens; [Genus] arcticus; [Genus] audax; [Genus] bangsi; [Genus] ferghanae; [Genus] gulosa; [Genus] haidarum; [Genus] herminea; [Genus] hibernicus; [Genus] imperii; [Genus] initis; [Genus] invicta; [Genus] kadiacensis; [Genus] kanei; [Genus] labiata; [Genus] leptus; [Genus] lymani; [Genus] microtis;  [Genus] mortigena; [Genus] muricus; [Genus] nippon; [Genus] olympica; [Genus] polaris; [Genus] pusilla; [Genus] richardsonii;  [Genus] rixosa; [Genus] salva; [Genus] seclusa; [Genus] semplei;  [Genus] streatori; [Genus] vulgaris; [Genus] whiteheadi (B141).

Names for new-borns / juveniles

Names for males --
Names for females --

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General Appearance

Body long and slender, head small, legs short, tail black-tipped all year (B52, B142, B148).

Similar Species

Larger than Mustela nivalis - weasel, with relatively longer and black-tipped tail (B142).
Sexual Dimorphism Male considerably larger than female - weight of male about 150% that of female (B142).

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Species Author

Debra Bourne

Major References

B51, B52, B141, B142, B143, B144, B147, B148, B221

Husbandry references:

(UK Contacts)

(Further Reading)
Click image for full contents list of ELECTRONIC LIBRARY

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TAXA Group (where information has been collated for an entire group on a modular basis)

Parent Group

  • Mustelids

Specific Needs Group referenced in Management Techniques

  • Mustelids

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Husbandry Information


Individual Techniques linked in Wildpro

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Appearance / Morphology

Measurement & Weight

Length Head-body length: approx. 20-30cm (B142); up to 29cm (B148).
  • male 17-24cm in North America (B52), 7.6-13in/19-33cm (B144), Britain range 27.5-31.2cm, mean 29.7cm, Ireland mean 25.2cm (B142
  • female 6.8-11in/17-27cm (B144), Britain range 24.2-29.2cm mean 26.4cm, Ireland mean 20.8cm (B142).
Height --
Adult weight General Up to 350g in Britain and New Zealand (B52).
Male 5-12.5oz./140-350g (B144); about 320g (Britain mean 32.1g range 200-445g, Ireland mean 233g) (B142), 60-200g in North America (B52).
Female 3.9-8.4oz./110-235g (B144); about 220g (Britain mean 21.3g range 140-280g, Ireland mean 123g) (B142).
New-born weight 0.09-0.15oz./2.6-4.2g (B144); 3-4g (B142).
Growth rate British animals: males about 260g and females about 190g by July (B142).

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  • Small (B148).
  • Skull: Flattened (B142).
  • Nose: Muzzle black, with long brown or white whiskers (B142).
  • Ears: nearly flat to head. Small and rounded (B142).
Dentition (Teeth)
  • I3/3, C1/1, P3/3, M1/1
  • Teeth specialised for carnivorous diet. Upper carnassials long and narrow, upper molars transversely elongated.

(B52, B142)

Eyes Slightly protruding, round, black (B142).

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Legs and Tracks

  • Five toes on both hind and fore feet.
  • Furred between pads.
  • Not webbed.


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  • Moderate length.
  • Brush tip black all year.

(B142, B144)

Length: approximately 6-12 cm (B142); up to 10cm B148.

  • male 2-5in/5-13cm (B144), Britain range 9.5-12.7cm mean 11.0cm.
  • female 2-4.4in./5-11cm (B144); Britain range 9.5-14.0cm mean 11.7cm (B142).

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Coat / Pelage

Adult Female
  • Dorsal: russet to ginger brown (B142); cinnamon-brown to yellow (B144), browny red (B148) rich chocolate brown (B147).
  • Ventral: white to cream. N.B. clear straight demarcation line from dorsal brown.
  • Tail tip: black.
  • Whiskers: very long, brown or white.

(B52, B142, B144, B147, B148)

Variations (If present) Winter:
  • White in cold climates including northern Scotland.
  • Part-white also occurs in some conditions.
  • Development or otherwise of white coat depends not on daylength but on minimum temperature, snowline, frost, altitude.
  • Winter fur denser than summer coat
  • Females more often white than males.

Mustela erminea hibernica Irish subspecies:

  • Irregular dividing line on flank between dorsal and ventral colouration - ventral colour usually reduced to midline stripe only (B142).

(B52, B142, B147, B148)

  • Two moults per year.
  • Timing controlled by daylength.
  • Spring moult: slow, starts head, progresses across back to abdomen.
  • Autumn moult: faster and in opposite direction.


New-born / Juvenile
  • At birth: fine down, white or pinkish.
  • Three weeks: prominent brown mane (temporary).
  • Eight weeks: full coat.

(B142, B147)

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Neonate (New-born) Characteristics

  • Blind, deaf, toothless.
  • Unable to maintain body temperature under 5-7 weeks.
  • Huddle together when female away.
  • Below 10-12░C enter reversible cold rigor (reduced cardiac and respiratory functions, reduced sensitivity).


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Detailed Anatomy Notes
(Summary information provided for pertinent species-specific data cross-referenced in Wildpro)

  • Reproductive: 4-5 pairs of teats (only visible in adult females). Testes in furred scrotum (not very visible in first-year individuals). Uterus simple shape (B142)(B144).
  • Scent glands: Anal glands under tail. Large especially in males (B142).

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Life Stages / Natural Diet / Physiology

Reproductive Stages

Breeding Season Mate in late spring/early summer (B52, B142, B147).
Oestrus / Ovulation
  • Post-partum oestrus and induced ovulation in adult females (B142).
  • Polyoestrus (B147).
Gestation / Pregnancy
  • Initial development of blastocysts for 2-3 weeks.
  • Delayed implantation 9-10 months.
  • Implantation photoperiod controlled (occurs in March).
  • Gestation length 4 weeks following implantation.

(B52, B142, B144, B147)

Parturition / Birth April/May (B142); May- June B148. In nest (B52).
Neonatal development
  • Birth: blind, deaf, toothless, fine down.
  • Three weeks: prominent temporary brown mane, deciduous teeth erupt.
  • 4 weeks: take solid food.
  • 5-6 weeks: eyes open (females earlier than males).
  • 5-7 weeks: begin to develop ability to maintain body temperature.
  • 8 weeks: fur fully grown, able to maintain body temperature when ambient temperature 0░C.

(B52, B142, B147)

Litter size
  • 4-9, maximum 13 (B144).
  • Average 9 embryos (range 6-13) but may be some resorptions (B142).
  • 4-7 (B148).
  • 4-9, up to 18 (B52).
Time between Litters / Litters per year One litter per year (B147).
Lactation / Milk Production 7-12 weeks (B142).
Sexual Maturity
  • Males after one year (B52, B144).
  • Females at 2.5-3 weeks old while still blind, deaf and helpless (B52, B142).
  • Average about 1 year - 1.1 years in females, 1.4 years in males, Swedish study (B142, B144).
  • Maximum wild individuals may reach 6-8 years in temperate countries (B142).

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Natural Diet

  • Mainly small mammals, usually up to rabbit/water vole size.
  • Rabbits important in Britain.
  • Voles most important in continental Europe, former USSR, North America
  • Also other rodents including squirrels, mice, brown rats, hares.
  • Also birds, eggs, lizards, frogs, snakes, insects
  • Earthworms and fruit such as blackberries may be taken when less food available.
  • Minimum estimated food requirements:
  • British stoats: males 57g/day (23% of body weight), females 33g/day (14% of body weight).
  • German stoats (in captivity) males 19-23% of body weight, females 23-27% of body weight.
  • 2-3 times increase in requirement for lactating female.
  • 5-10 times increase for female while providing for dependant weaned juveniles.

(B52, B142, B144, B147, B148)

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Detailed Physiology Notes
(Summary information provided for pertinent species-specific data cross-referenced in Wildpro)

Temperature 38-40░C (B142).
Pulse Male average 402 (range 360-480), female average 421 (range 360-510) (B142).
Respiration 86-100 breaths per minute (B142).
Faeces 4-8cm long, thin, with hard black mucilage covering when dry (B142).
Haematology / Biochemistry --
Chromosomes 2n = 44 (B142).
Other --

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Feeding Behaviour

  • Hunt along familiar routes, alone or as family, in zigzag pattern.
  • Concentrate effort in most profitable areas.
  • Select larger prey when prey abundant.
  • Locate prey mainly be sight and sound.
  • Kill by rapid accurate bite at back of neck.
  • Larger prey do not die instantly - probably die from shock.
  • Cache surplus prey.

(B142, B147)

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Parental Behaviour

  • Cared for by female
  • Male plays no role in rearing offspring


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Social Behaviour / Territoriality

  • Variable territory size.
  • Sexes live separately.
  • Resident individuals defend territory against others of same sex.
  • Male territory may include territory of one or more females.
  • Territory size depends on available prey.
  • Male territoriality breaks down in spring, with dominant males ranging widely searching for mates.
  • "Hunting in packs" probably family of female and juveniles.
  • Scent mark by anal drag to mark resident territory.
  • Scent mark by body rubbing during agonistic interactions.
  • More frequent scent marking by dominant animals.
  • Male increases in dominance with: length of residence in area, age, size.
  • Dominant males outrank other males (younger and intruders) and all females except females with young.
  • Offensive behaviour more threats and chasing than actual fights.
  • Males usually disperse, females usually remain close to natal area.

(B142) (B144, B147)

Inter-specific --

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Sexual Behaviour

  • Males mate both adult females and juveniles in nest.
  • Dominant males may range widely looking for mates.
  • Young males may stay close to single resident female.


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Predation in Wild

Large carnivores, predatory birds (hawks, owls) (B142, B144),

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Activity Patterns

  • Mainly terrestrial.
  • Active for periods of e.g. 10-45 minutes, with periods of rest between.
  • Longer active periods and greater distances covered if prey scarce.
  • Travel along hedges/stone walls rather than across open spaces.
  • Use regular routes.
  • Remain under snow in very cold climates.
  • Climb well.
  • Swim well
  • Run down tree trunks head first.

(B142, B143, B147, B148)

  • Active at all hours although variation with season.
  • Mainly nocturnal autumn and winter
  • More diurnal activity spring and summer
  • Diurnal activity starts earlier in spring for males than for females


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Habitat and Range

General Habitat Type

  • Wide habitat range - anywhere with sufficient prey and cover.
  • e.g. tundra, farmland (pastures and arable), woodland (coniferous, mixed), moorland, marsh, mountains, riverbanks, lake shores.
  • Mature forests not good habitat as little ground cover, less small mammals available as prey.
  • Found up to 3,000m.

(B51, B142, B147)

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Nests / Burrows / Shelters

  • May be 2 to10 dens in a territory.
  • Dens formed from nests of prey, or in crevice, hollow log or tree roots.
  • Line with dry vegetation or fur from prey.
  • Also use temporary resting places.

(B142, B147)

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Distribution and Movement (Migration etc.)

  • Northern Holarctic.
  • South to about 40░N.
  • Central and northern Europe, Asia including Japan, northern North America (Alaska to northern New Mexico and Maryland), north-eastern Greenland.
  • Europe: Ireland and Scandinavia to north-eastern Siberia and western Himalayas. Not in Mediterranean or some north Atlantic islands.
  • Britain and Ireland: throughout mainland areas at all altitudes. Also many offshore islands greater than 60 square km.
  • Not resident on some remote larger islands or on smaller islands.

(B51, B52, B142, B143, B147, B148)

Occasional and Accidental Transient to smaller islands up to about 1km offshore (B142)

New Zealand (B51, B52, B142, B143)

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Intraspecific variation

Three subspecies recognised:
  • Mustela erminea erminea
  • Mustela erminea hibernica (Thomas & Barrett-Hamilton, 1895) Irish subspecies irregular dividing line on flank between dorsal and ventral colouration.
  • Mustela erminea minima Cavazza, 1912.

British form (larger than continental Europe) not sufficiently distinct for sub-specific status (former suggestion Putorius erminea stabalis Barrett-Hamilton 1904).

Islay and Jura form not recognised as subspecies (former suggestion Putorius erminea ricinae Miller 1907).

(B142, B143).

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Conservation Status

Wild Population -
  • Not rare, not endangered (B144).

  • In the UK: native, common but possibly declining. Pre-breeding population estimate of about 462,000, including 245,000 in England, 180,000 in Scotland, 37,000 in Wales. Population estimate was "based on a very limited amount of information for the species" although additional knowledge "may not necessarily have made a substantial difference to the estimate". (B221)

General Legislation
  • Legal protection in Ireland (Eire). (B142).
  • Bern Convention Appendix III (B143).
CITES listing --
Red-data book listing --
Threats May be affected by secondary poisoning by eating rodents which have been contaminated with insecticides or molluscicides (B221)
Captive Populations --
Trade --

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