The long-tailed weasel (''Neogale frenata''), also known as the bridled weasel, masked ermine, or big stoat, is a species of
weasel
Weasels are mammals of the genus ''Mustela'' of the family Mustelidae. The genus ''Mustela'' includes the least weasels, polecats, stoats, ferrets, and European mink. Members of this genus are small, active predators, with long and slend ...
found in
North
North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography.
Etymology
T ...
,
Central, and
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
. It is distinct from the
short-tailed weasel (''Mustela erminea''), also known as a "stoat", a close relation in the genus ''
Mustela'' that originated in
Eurasia
Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...
and crossed into
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
some
half million years ago; the two species are visually similar, having long, slender bodies and tails with short legs and a black tail tip.
Long-tailed weasels exhibit scale-dependent patterns of habitat selection, favoring forest patches, fencerows, and drainage ditches while avoiding agricultural fields.
[Gehring, T. M., & Swihart, R. K. (2021). Habitat use by Long-tailed Weasels in a Fragmented Agricultural Landscape. The American Midland Naturalist, 186(1), 136–149.] They typically make their habitats in forests and underground in burrows of other small mammals.
Taxonomy
The long-tailed weasel was originally described in the genus ''
Mustela'' with the name ''Mustela frenata'' by
Hinrich Lichtenstein
Martin H nrich Carl Lichtenstein (10 January 1780 – 2 September 1857) was a German physician, List of explorers, explorer, botanist and zoologist. He explored parts of southern Africa and collected natural history specimens extensively and ...
in 1831.
["Species , Accepted: ''Mustela frenata'' Lichtenstein, 1831"](_blank)
''Global Biodiversity Information Facility
The Global Biodiversity Information Facility (GBIF) is an international organisation that focuses on making scientific data on biodiversity available via the Internet using web services. The data are provided by many institutions from around th ...
''. Retrieved 19 May 2023.["BC Conservation Data Centre: Species Summary ''Mustela frenata'' Long-tailed Weasel"](_blank)
'' British Columbia Ministry of Environment''. 8 March 2005. Retrieved 19 May 2023. In 1993, the classification, ''Mustela frenata'', was accepted into the second edition of the ''
Mammal species of the world: a taxonomic and geographic reference'', which was published by the ''
Smithsonian Institution Press''.
The species, with classification and name ''Mustela frenata'', was accepted into the
Global Biodiversity Information Facility
The Global Biodiversity Information Facility (GBIF) is an international organisation that focuses on making scientific data on biodiversity available via the Internet using web services. The data are provided by many institutions from around th ...
.
Later, in a study published in 2021 in the ''Journal of Animal Diversity'', Bruce Patterson ''et al.'' reclassified the long-tailed weasel into the genus ''
Neogale
''Neogale'' (colloquially referred to as the New World weasels) is a genus of Carnivora, carnivorous, highly active small Mammal, mammals belonging to the Mustelidae family (which also contains badgers, weasels, martens, otters, and wolverines, ...
'' along with two other former ''Mustela'' species, as well as the two species formerly classified in ''
Neovison''.
Evolution

The long-tailed weasel is the product of a process begun 5–7 million years ago, when northern forests were replaced by open grassland, thus prompting an explosive evolution of small, burrowing rodents. The long-tailed weasel's ancestors were larger than the current form, and underwent a reduction in size to exploit the new food source. The long-tailed weasel arose in North America 2 million years ago, shortly before the
stoat
The stoat (''Mustela erminea''), also known as the Eurasian ermine or ermine, is a species of mustelid native to Eurasia and the northern regions of North America. Because of its wide circumpolar distribution, it is listed as Least Concern on th ...
evolved as its mirror image in
Eurasia
Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...
. The species thrived during the
Ice Age
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and g ...
, as its small size and long body allowed it to easily operate beneath snow, as well as hunt in burrows. The evolution of an elongated body shape maximizes the efficiency with which ''Mustela frenata'' can trap prey underground, as the majority of it lives in burrows and in tunnels.
[Frey, Jennifer K. ''Wild Carnivores of New Mexico''. Accessed April 24, 2025.] The long-tailed weasel and the stoat remained separated until half a million years ago, when falling
sea level
Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...
s exposed the
Bering land bridge
Beringia is defined today as the land and maritime area bounded on the west by the Lena River in Russia; on the east by the Mackenzie River in Canada; on the north by 72° north latitude in the Chukchi Sea; and on the south by the tip of the ...
, thus allowing the stoat to cross into North America. However, unlike the latter species, the long-tailed weasel never crossed the land bridge, and did not spread into Eurasia.
Description
The long-tailed weasel is one of the larger
weasel
Weasels are mammals of the genus ''Mustela'' of the family Mustelidae. The genus ''Mustela'' includes the least weasels, polecats, stoats, ferrets, and European mink. Members of this genus are small, active predators, with long and slend ...
s (comprising both ''Neogale'' and ''Mustela'') in
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
. There is substantial disagreement both on the upper end of their size and difference in size by sex by source: one indicates a body length of and a tail comprising 40–70% of the head and body length. It adds that in most populations, females are 10–15% smaller than males,
thus making them about the same size as large male
stoat
The stoat (''Mustela erminea''), also known as the Eurasian ermine or ermine, is a species of mustelid native to Eurasia and the northern regions of North America. Because of its wide circumpolar distribution, it is listed as Least Concern on th ...
s, according to a second source.
A third states they range from 11 to 22 inches (280–560 mm) in length, with the tail measuring an additional 3 to 6 inches (80–150 mm). It maintains the long-tailed weasel weighs between 3 and 9 ounces (85-267 g) with males being about twice as large as the females.
[LONG-TAILED WEASEL (Mustela frenata), Description; Northern State University, Aberdeen, South Dakota](_blank)
/ref>
The eyes are black in daylight, but glow bright emerald green when caught in a spotlight at night. The dorsal fur is brown in summer, while the underparts are whitish and tinged with yellowish or buffy brown from the chin to the inguinal region. The tail has a distinct black tip. Long-tailed weasels in Florida
Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
and the southwestern US may have facial markings of a white or yellowish colour. In northern areas in winter, the long-tailed weasel's fur becomes white, sometimes with yellow tints, but the tail retains its black tip. The long-tailed weasel moults twice annually, once in autumn
Autumn, also known as fall (especially in US & Canada), is one of the four temperate seasons on Earth. Outside the tropics, autumn marks the transition from summer to winter, in September (Northern Hemisphere) or March ( Southern Hemisphe ...
(October to mid-November) and once in spring (March–April). Each moult takes about 3–4 weeks and is governed by day length and mediated by the pituitary gland
The pituitary gland or hypophysis is an endocrine gland in vertebrates. In humans, the pituitary gland is located at the base of the human brain, brain, protruding off the bottom of the hypothalamus. The pituitary gland and the hypothalamus contr ...
. Unlike the stoat, whose soles are thickly furred all year, the long-tailed weasel's soles are naked in summer. The long-tailed weasel has well-developed anal scent glands, which produce a strong and musky odour. Analysis of a dichloromethane extract of the anal gland secretion showed it contained 2,2-dimethylthietane, 2,4-dimethylthietane, 2,3-dimethylthietane, 2-propylthietane, 3,3-dimethyl-1,2-dithiolane, 3-ethyl-1,2-dithiolane, indole and 2-aminoacetophenone. Unlike skunk
Skunks are mammals in the family Mephitidae. They are known for their ability to spray a liquid with a strong, unpleasant scent from their anal glands. Different species of skunk vary in appearance from black-and-white to brown, cream or gi ...
s, which spray their musk, the long-tailed weasel drags and rubs its body over surfaces in order to leave the scent, to mark their territory and, when startled or threatened, to discourage predators.
Habitat
Habitat type
Long-tailed weasels are found in a variety of habitats, but have been found to make use of both coniferous
Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...
and deciduous
In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...
forests in a mix of mid-successional and early-successional stages. They prefer open forests, wooded areas, or shrub lands as they offer optimal cover for habitation and hunting. Long-tailed weasal habitats range in altitude from sea level to alpine meadow. Typically, long-tailed weasels are not present in dry brush, shrub, and scrub habitats such as deserts
A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the l ...
. It is assumed that long-tailed weasels are susceptible to habitat fragmentation, as they avoid habitation of areas used for farming.
Habitat size and distribution
The home range of the long-tailed weasel is estimated to range between 10-20 ha (25-50 ac) with densities of 1 weasel/km² (2.6/mi²), with the maximum number of weasels being 7 weasel/km² (18/m²). Long-tailed weasels are solitary in nature and prefer distance between themselves and members of their own species.
Identification
Tracks and scat
The footprint of a long-tailed weasel is about 1 inch (25 mm) long. Although they have five toes, only four of them can be seen in their tracks. The only exception to this is when walking in the snow or mud, all five of their toes are shown. Their footprints will also appear heavier if the weasel is carrying food. Another way to determine the presence of a weasel is by looking for wavy indents made by their tails in the snow.
The long-tailed weasel uses one spot to leave their feces. This spot is usually near where they burrow. They'll continuously use this spot for their droppings until it gets covered by environmental changes.
Distinguishing features
A black-tipped tail, yellowish-white belly fur, and brown fur on its back and sides are distinguishing for the long-tailed weasel. Additionally, the long-tailed weasel has long whiskers, a long narrow body, short legs, and a long tail that is approximately half the length of the body and head of the weasel.["Long-tailed Weasel Facts"](_blank)
''Washington Nature Mapping Program''. Retrieved 3 June 2021.[NatureWorks]
'' NHPBS''. Retrieved 3 June 2021.[Montana Field Guide]
"Long-tailed Weasel — Mustela frenata"
''Montana Natural Heritage Program and Montana Fish, Wildlife and Parks''. Retrieved 3 June 2021. The long-tailed weasel has a triangular-shaped head, which is accentuated by small, round ears towards the back of the head. Males can be up to double the weight of females due to the size of the skull. Female long-tailed weasels have narrower skulls, which allows for more efficient hunting within the burrows of their rodent prey. Compared to the short-tailed weasel the long-tailed weasel lacks a white line on the insides of its legs.
Behaviour
Reproduction and development
The long-tailed weasel mates in July–August, with implantation of the fertilized egg on the uterine wall being delayed until about March. The gestation period
In mammals, pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation. It begins when a fertilized zygote implants in the female's uterus, and ends once i ...
lasts 10 months, with actual embryonic development taking place only during the last four weeks of this period, an adaptation to timing births for spring, when small mammals are abundant. Litter size generally consists of 5–8 kits, which are born in April–May. The kits are born partially naked, blind and weighing , about the same weight of a hummingbird
Hummingbirds are birds native to the Americas and comprise the Family (biology), biological family Trochilidae. With approximately 366 species and 113 genus, genera, they occur from Alaska to Tierra del Fuego, but most species are found in Cen ...
. The long-tailed weasel's growth rate is rapid, as by the age of three weeks, the kits are well furred, can crawl outside the nest and eat meat. At this time, the kits weigh . At five weeks of age, the kit's eyes open, and the young become physically active and vocal. Weaning begins at this stage, with the kits emerging from the nest and accompanying the mother in hunting trips a week later. The kits are fully grown by autumn, at which time the family disbands. The females are able to breed at 3–4 months of age, while males become sexually mature at 15–18 months.
Denning and sheltering behaviour
The long-tailed weasel dens in ground burrows, under stumps
In cricket, the stumps are the three vertical posts that support the bails and form the wicket. '' Stumping'' or ''being stumped'' is a method of dismissing a batsman.
The umpire ''calling stumps'' means the play is over for the day.
Part of ...
or beneath rock piles. It usually does not dig its own burrows, but commonly uses abandoned chipmunk
Chipmunks are small, striped rodents of subtribe Tamiina. Chipmunks are found in North America, with the exception of the Siberian chipmunk which is found primarily in Asia.
Taxonomy and systematics
Chipmunks are classified as four genera: '' ...
, ground squirrel, gopher, mole, and mountain beaver holes. The diameter nest chamber is situated around from the burrow entrance, and is lined with straw and the fur of prey.
Defense
The enemies of the long-tailed weasel are usually coyotes, foxes
Foxes are small-to-medium-sized omnivorous mammals belonging to several genera of the family Canidae. They have a flattened skull; upright, triangular ears; a pointed, slightly upturned snout; and a long, bushy tail ("brush").
Twelve species ...
, wildcats, wolves
The wolf (''Canis lupus''; : wolves), also known as the grey wolf or gray wolf, is a canine native to Eurasia and North America. More than thirty subspecies of ''Canis lupus'' have been recognized, including the dog and dingo, though gr ...
, and the Canadian lynx. The weasel will give off its musky odor, however, this is not primarily used when encountering other creatures. When leaving an area they were just in, they will leave their odor behind. This is done by the weasels taking themselves and hauling their bodies across surfaces they just interacted with. The long-tailed weasel does this to "discourage predators" from coming back to the area, possibly indicating that the weasel considers this a safe haven for return. This type of reaction is also reserved for when the weasel feels it is in danger, or when it is looking for a mate. Tree-climbing is another type of defense mechanism that long-tailed weasels utilize against predators on the ground. These weasels will climb up a reasonable height of a tree when they sense that they are in danger. They will then sit silent and "motionless", while looking at their presumed predator. These weasels keep their guard up like this until the predator leaves, and when the weasel considers itself no longer in danger.
Another common defense of long-tailed weasels is its black-tipped tail, which differs in color from the rest of the body. When the long-tailed weasel becomes more white in the winter
Winter is the coldest and darkest season of the year in temperate and polar climates. It occurs after autumn and before spring. The tilt of Earth's axis causes seasons; winter occurs when a hemisphere is oriented away from the Sun. Dif ...
, this defense mechanism is especially used. The black-tipped tail distracts predators from the rest of the body, as it is more visible to the eye of a predator. This causes the visibility of the actual weasel to be rather difficult and makes the predator attack the tail instead of the weasel. The weasel is allowed to escape the predator because of this.
Diet
The long-tailed weasel is a fearless and aggressive hunter which may attack animals far larger than itself. When stalking, it waves its head from side to side in order to pick up the scent of its prey. It hunts small prey, such as mice
A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
, by rushing at them and killing them with one bite to the head. With large prey, such as rabbit
Rabbits are small mammals in the family Leporidae (which also includes the hares), which is in the order Lagomorpha (which also includes pikas). They are familiar throughout the world as a small herbivore, a prey animal, a domesticated ...
s, the long-tailed weasel strikes quickly, taking its prey off guard. It grabs the nearest part of the animal and climbs upon its body, maintaining its hold with its feet. The long-tailed weasel then manoeuvres itself to inflict a lethal bite to the neck.
The long-tailed weasel is an obligate carnivore which prefers its prey to be fresh or alive, eating only the carrion stored within its burrows. Rodent
Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...
s are almost exclusively taken when they are available. Its primary prey consists of mice
A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
, rat
Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include '' Neotoma'' (pack rats), '' Bandicota'' (bandicoo ...
s, squirrel
Squirrels are members of the family Sciuridae (), a family that includes small or medium-sized rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrel ...
s, chipmunk
Chipmunks are small, striped rodents of subtribe Tamiina. Chipmunks are found in North America, with the exception of the Siberian chipmunk which is found primarily in Asia.
Taxonomy and systematics
Chipmunks are classified as four genera: '' ...
s, shrew
Shrews ( family Soricidae) are small mole-like mammals classified in the order Eulipotyphla. True shrews are not to be confused with treeshrews, otter shrews, elephant shrews, West Indies shrews, or marsupial shrews, which belong to dif ...
s, moles and rabbits. Occasionally, it may eat small bird
Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...
s, bird eggs, reptile
Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...
s, amphibian
Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
s, fish
A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...
, earthworm
An earthworm is a soil-dwelling terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class (or subclass, depending on the author) Oligochaeta. In classical systems, they we ...
s and some insect
Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
s. The species has also been observed to take bat
Bats are flying mammals of the order Chiroptera (). With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most birds, flying with their very long spread-out ...
s from nursery colonies. It occasionally surplus kills, usually in spring when the kits are being fed, and again in autumn. Some of the surplus kills may be cached, but are usually left uneaten. Kits in captivity eat from a quarter to half of their body weight in 24 hours, while adults eat only one fifth to one third. After killing its prey, the long-tailed weasel laps up the blood, but does not suck it, as is popularly believed. With small prey, also the fur, feathers, flesh and bones are consumed, but only some flesh is eaten from large prey. When stealing eggs, the long-tailed weasel removes each egg from its nest one at a time, then carries it in its mouth to a safe location where it bites off the top and licks out the contents or if they have babies in the den they may hold it in their mouth all the way back to them.
Subspecies
, 42 subspecies are recognised.
Cultural meanings
In North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
, Native Americans (in the region of ) deemed the long-tailed weasel to be a bad sign; crossing its path meant a "speedy death".
References
Notes
Bibliography
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External links
{{Authority control
Weasels
Carnivorans of North America
Carnivorans of Central America
Carnivorans of Brazil
Mammals of Canada
Mammals of Colombia
Mammals of Ecuador
Mammals of Mexico
Mammals of Peru
Mammals of the United States
Mammals of Venezuela
Least concern biota of North America
Least concern biota of South America
Mammals described in 1831
Taxobox binomials not recognized by IUCN
Taxa named by Hinrich Lichtenstein