There are 16 Palearctic and 10 Nearctic subspecies recognized.
Ermine have keen senses of smell, vision, hearing, and touch that help them to locate prey. Most mustelids are fairly quiet animals, but some vocalizations may be used in intra-specific communication. Chemical cues are probably the main means of communicating reproductive readiness to potential mates.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Ermine are not considered threatened or endangered, although hunting pressure in some areas may impact populations severely.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Ermine, and other Mustela species can take domestic fowl when they can gain access to them.
Humans trap thousands of ermine each season, but the demand for pelts has recently decreased. The white winter fur has long been used in trimming coats and making stoles. Ermine are excellent mousers, which makes them valuable to humans.
Positive Impacts: body parts are source of valuable material; controls pest population
Ermine are important predators on small mammal communities in the ecosystems in which they live.
Many ermine die from a parasitic nematode (Skrjabingylus nasicola) that infects the nasal passage, distorting the sinuses. Eventually the skull is perforated and pressure is exerted on the brain, causing death. Shrews are believed to be the carrier hosts of this parasite.
Commensal/Parasitic Species:
Ermine are carnivores that hunt primarily at night. They are specialist predators on small, warm-blooded vertebrates, preferably mammals of rabbit size and smaller. When mammalian prey is scarce, ermine eat birds, eggs, frogs, fish, and insects. In severe climates, ermine frequently hunt under snow and survive entirely on small rodents and lemmings. Daily meals are essential to meet the ermine's exhorbitant energy and heat production demands. Ermine cache leftover meals as a way of dealing with these demands.
Once a potential prey is identified, the ermine approaches as closely as possible. With incredible speed it grasps the back of the victim's head and neck with sharp teeth, and wraps its body and feet around the victim. The victim dies from repeated bites to the base of the skull. Ermine have keen senses that help them locate prey. Hares and rodents are mainly followed by scent, insects by sound, and fish by sight.
Animal Foods: birds; mammals; amphibians; fish; eggs; insects
Foraging Behavior: stores or caches food
Primary Diet: carnivore (Eats terrestrial vertebrates)
Ermine have a circumpolar distribution. They are found in the north temperate regions of Eurasia and North America. In the New World, they range from east to west in a broad belt from the Arctic Ocean and adjacent islands of the Canadian Archipelago southward into the northern United States. Ermine are absent from the Great Plains.
Biogeographic Regions: nearctic (Native ); palearctic (Native )
Other Geographic Terms: holarctic
Ermine prefer riparian woodlands, marshes, shrubby fencerows, and open areas adjacent to forests or shrub borders. Although ermine are primarily terrestrial, they climb trees and swim well. Tree roots, hollow logs, stone walls, and rodent burrows are used as dens. Dens are usually around 300 mm below ground. Ermine line their nests with dry vegetation, and fur and feathers from prey. Side cavities of burrows are used as food caches and latrines.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: tundra ; taiga ; savanna or grassland ; forest ; scrub forest ; mountains
Other Habitat Features: riparian
The average life span of an ermine is 1 to 2 years; the maximum is 7 years.
Range lifespan
Status: wild: 7 (high) years.
Typical lifespan
Status: wild: 1 to 2 years.
Average lifespan
Status: wild: 1-2 years.
Range lifespan
Status: captivity: 12.5 (high) years.
At full adult size total body length from head to rump is 170 mm to 330 mm. Males are generally twice as large as females, with males weighing from 67 to 116 grams and females from 25 to 80 grams. The tail length is about 35% of the total body length, ranging from 42 mm to 120 mm. Ermine have the typical weasel form: long body, short legs, long neck supporting a triangular head, slightly protruding round ears, bright black eyes, and long whiskers. Their short, moderately fine fur is white in the winter and the tip of the tail is black. In the summer, the dorsal fur is chocolate brown while the ventral fur extending to the upper lip is yellowish white.
Range mass: 25 to 116 g.
Range length: 170 to 330 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Average basal metabolic rate: 1.276 W.
Ermine are fierce and aggressive, although diminutive, animals. Potential predators are larger carnivores including red fox, gray fox, martens, fishers, badgers, raptors, and occasionally domestic cats.
Known Predators:
Ermine are a polygynous-promiscuous species, with males and females mating opportunistically.
Mating System: polygynandrous (promiscuous)
Ermine mate in late spring to early summer. Females are polyestrous, but produce only 1 litter per year. Young are born in April or May after an average gestation period of 280 days, which includes an 8 to 9 month period of developmental delay. Longer days beginning in March trigger the resumption of fetal development. Litter size ranges from 3 to 18 offspring and averages 4 to 9. The sex ratio is unequal. Young are blind and helpless. They are covered with fine white hair, and a prominent dark mane of dense fur develops around the neck by the third week (function unknown). The young grow quickly and are able to hunt with their mother by their eighth week. Although females do not reach adult size until a least 6 weeks after birth, they are able to mate when they are 60 to 70 days old, often before they are weaned. Males do not breed or gain adult dimensions until their second summer.
Females in nature may survive for at least 2 breeding seasons, while males generally do not survive this long. Reproductive success is highly dependent on food availability.
Breeding interval: Ermine generally breed once yearly.
Breeding season: Ermine mate in late spring to early summer.
Range number of offspring: 3 to 18.
Average number of offspring: 4-9.
Average gestation period: 280 days.
Average weaning age: 8-10 weeks.
Average age at sexual or reproductive maturity (female): 60-70 days.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous ; delayed implantation ; embryonic diapause
Average birth mass: 2.3 g.
Average gestation period: 43 days.
Average number of offspring: 6.77.
Average age at sexual or reproductive maturity (male)
Sex: male: 365 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 95 days.
Females exclusively care for their offspring, nursing and protecting them until they become independent. The young are born blind and helpless.
Parental Investment: no parental involvement; altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
