---
title: "What the sources say about the Least Weasel | AnimalTracks.wiki"
description: "65 claims from the Least Weasel profile, each beside the words of the source that backs it."
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# What the sources say about the Least Weasel (*Mustela nivalis*)

> 65 claims from the Least Weasel profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Least Weasel](https://animaltracks.wiki/animals/least-weasel/)

## Mustela nivalis (least weasel). Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Mustela_nivalis/

| The page says | The source says |
| :--- | :--- |
| Weighing as little as 30 grams | Range mass 30 to 100 g (note: tagline; prey and weight clauses are the next two claims) |
| kills prey larger than itself | weasels frequently kill prey larger than themselves |
| can eat over half its own body weight in a day | Weasels can consume over 50% of their body weight every day |
| Grassland, forest, tundra and farmland across the Northern Hemisphere | Least weasels are widespread and abundant throughout the Northern Hemisphere (note: stats.habitat) |
| Grassland, forest, tundra and farmland | They are found in prairie grasslands, coniferous and deciduous forests, open tundra, bushy taiga (note: stats.habitat) |
| farmland | such as those found in prairie habitats or on agricultural lands (note: stats.habitat) |
| Voles and mice | Field voles , wood mice , and bank voles constitute much of a least weasel’s diet in more southern populations (note: stats.diet) |
| lemmings in the Arctic | Rodents, especially collared lemmings in the northern arctic regions, are vitally important (note: stats.diet) |
| birds' eggs | least weasels will also feed upon birds’ eggs, lizards, amphibians, small fish, and invertebrates (note: stats.diet) |
| Kills prey larger than itself | weasels frequently kill prey larger than themselves (note: stats.superpower; weight clause is the claim above) |
| long, tubular body and short limbs | a typical mustelid body shape: a long, tubular body, with short limbs |
| it moves easily through leaf litter, underground tunnels and subnivean tunnels, which are the ones beneath the snow | maneuvering easily through both leaf litter, subterranean, and subnivean tunnels (note: 'beneath the snow' is the definition of subnivean (term gloss, not a source claim)) |
| It does not dig its own den. It uses dens abandoned by its prey or other burrowing animals. | do not burrow or dig dens; they use the abandoned dens from prey or other fossorial species |
| Across its range a least weasel weighs 30 to 100 grams | Range mass 30 to 100 g |
| Tiny: 30 to 100 grams | Range mass 30 to 100 g (note: FAQ 1; the length clause is the next claim) |
| measures 165 to 217 millimetres including the tail | Range length 165 to 217 mm (note: ADW's text says total lengths include the tail) |
| including the tail | can reach total lengths (including the tail) over 217 mm |
| males are the bigger sex | Sexual Dimorphism male larger |
| Individuals from warmer climates tend to be bigger | individuals from warmer climates tend to have larger body sizes and masses than those from colder climates |
| populations in North Africa can weigh over 70 grams | such as individuals from populations of North Africa, which can weigh over 70 grams |
| North American weasels average about 45 grams and about 190 millimetres | The smallest weasels are in North American populations and weigh, on average about 45 grams, and average about 190 mm in length (including the tail) |
| native from Alaska through Canada and the northern United States, and in Europe outside Ireland | native to North America, from Alaska, south throughout Canada and the northern United States, and Europe (excluding Ireland, Greenland, and Iceland) |
| In northern populations the coat turns pure white in winter, but it always lacks the black tail tip that stoats and long-tailed weasels carry. | The pelage color changes seasonally in northern populations, but not in more southerly populations. In the winter, the coat is pure white, but always lacking the black tail tip found in two similar species |
| stores little fat, has very high metabolic demands | Because least weasels are so small, have limited abilities in storing fat, and have such high metabolic demands |
| must eat very regularly to avoid starving | Least weasels must eat very regularly to avoid starvation and death |
| more than half its body weight in food every day, and more still in winter | Weasels can consume over 50% of their body weight every day and even more so in the winter months. |
| it is often out foraging day or night | are often found foraging at all hours, day or night |
| Field voles, wood mice and bank voles make up much of the diet in southern populations, and when rodents are plentiful they can be almost 100 percent of it. | almost 100 percent of a weasel's diet is made up of rodents if they are abundant |
| In the Arctic, collared lemmings are vitally important for breeding success. | Rodents, especially collared lemmings in the northern arctic regions, are vitally important for weasel reproductive success. |
| When rodents are scarce, a weasel will switch to birds' eggs, lizards, amphibians, small fish and invertebrates, and it will not turn down carrion. | When rodents are scarce, least weasels will also feed upon birds’ eggs, lizards, amphibians, small fish, and invertebrates. |
| it will not turn down carrion | will not overlook an easy meal, such as carrion |
| A weasel often takes down animals bigger than itself, but each meal is only a few grams of meat. | weasels frequently kill prey larger than themselves, yet they only eat a few grams of meat per meal |
| The leftovers are cached, hidden near the den entrance for later. | Caches are concealed around the den entrance |
| Kits are born hairless and helpless. | Kits are born hairless and helpless |
| Gestation lasts about a month. | Gestation lasts approximately one month |
| By about 47 days they can kill prey for themselves. | At about 47 days, the kits are able to kill prey for themselves |
| Killing is an innate behaviour: captive kits with no experience of prey still kill it, though kits that stay with their mother have higher success rates. | killing is an innate behavior and kits in captivity kill prey with no previous experience or exposure to prey; however, kits that remain with their mother and gain practical hunting experience have higher success rates |
| a litter can reach 15 kits and a female can have up to three litters in a year | up to 15 offspring can be born, and up to three litters per year can occur |
| When prey is plentiful, as when Arctic lemming numbers boom | During years of high prey abundance and in areas such as the Arctic, where lemming populations can reach astronomical numbers |
| Owls, falcons, eagles and hawks typically prey on adults | adults are typically preyed upon by owls, such as tawny owls , and other birds of prey, such as falcons, eagles, and hawks (note: foxes and snakes are juvenile predators in ADW; larger weasels follows) |
| snakes and foxes often take the young | Juvenile mortality is common from predation by snakes and foxes |
| larger weasels such as the stoat may also eat least weasels | Least weasels may also be preyed upon by other larger weasel species, such as ermines and long-tailed weasels |
| camouflage, hiding, biting and noise | Least weasels can counteract predation events by using their camouflaged pelage to blend in with substrate and aggressive behavior, such as vocalizations and biting, and by hiding in shelters |
| when cornered or startled it can discharge a foul-smelling fluid from its anal glands | When cornered or startled, anal gland secretions can be discharged, which release a foul-smelling fluid that can deter an antagonist. |
| weasel war dance, a series of leaps and twists with an arched back and stiff limbs, often with bark-like calls | “weasel war dance”, a colloquial term used to describe a intermittent series of leaps and twists, often accompanied by bark-like vocalizations, stiff limbs, an arched back |
| It is thought to perplex prey, but that is one hypothesis | One hypothesis is that the war dance is thought to perplex prey and to give the weasel a hunting advantage |
| there is no solid scientific evidence explaining it, and weasels have been seen dancing without an audience | at this time, there is no solid scientific evidence explaining this behavior ... there are cases where the weasels perform this “dance” lacking an audience |
| 165 to 217 millimetres from nose to tail tip | Range length 165 to 217 mm (note: FAQ 1; ADW's total lengths include the tail) |
| a least weasel in winter white always lacks the stoat's black tail tip | In the winter, the coat is pure white, but always lacking the black tail tip found in two similar species |
| Built for Tunnels | maneuvering easily through both leaf litter, subterranean, and subnivean tunnels |
| Eating Half Its Weight | Weasels can consume over 50% of their body weight every day |
| Musk and the War Dance | “weasel war dance”, a colloquial term (note: heading; musk: ADW 'anal glands, or musk glands', claimed in the body) |
| North American animals are the smallest, averaging about 45 grams | The smallest weasels are in North American populations and weigh, on average about 45 grams |
| The menu is mostly rodents. | Least weasels are highly specialized rodent predators and as such, they rely heavily upon rodent species for food. |
| Born Ready | killing is an innate behavior |
| Prey numbers have a dramatic effect on how many litters and young a female has. | Prey density has a dramatic effect on the number of litters per year and the number of young per litter. |
| A weasel this size is prey for plenty of animals. | Known Predators red foxes ( Vulpes vulpes ) grey foxes |
| The stoat is a larger weasel species that can prey on least weasels | Least weasels may also be preyed upon by other larger weasel species, such as ermines and long-tailed weasels (note: FAQ 2; ermine is the stoat (ADW: 'ermines, or stoats')) |
| The least weasel's war dance is a series of leaps and twists with an arched back and stiff limbs, often with bark-like calls | “weasel war dance”, a colloquial term used to describe a intermittent series of leaps and twists, often accompanied by bark-like vocalizations, stiff limbs, an arched back (note: vibe.reason) |
| tags: agile | maneuvering easily through both leaf litter, subterranean, and subnivean tunnels (note: task #1246; Agile tag kept: quick manoeuvring over tangled ground and through tunnels; the war dance in the body is the other half.) |

## Mustela nivalis. AnAge: The Animal Ageing and Longevity Database.

https://genomics.senescence.info/species/entry.php?species=Mustela_nivalis

| The page says | The source says |
| :--- | :--- |
| In captivity the oldest recorded least weasel reached 9.1 years. | Maximum longevity 9.1 years (captivity) |
| The AnAge database gives a maximum longevity of 9.1 years in captivity. That is a captive figure, not a wild one. | Maximum longevity 9.1 years (captivity) |
| weightKg: 0.0469 | Adult weight 46.9 g (note: task #1246; AnAge adult weight; Micro class (under 100 g). Name guess would have been Medium.) |

## Abramov (2025). Mustela nivalis. The IUCN Red List of Threatened Species 2025: e.T70207409A215863028.

https://doi.org/10.2305/iucn.uk.2025-1.rlts.t70207409a215863028.en

| The page says | The source says |
| :--- | :--- |
| Least Concern | IUCN Red List category: Least Concern (LC). (note: stats.conservationStatus; category read through GBIF's copy of the Red List (assessment DOI cited)) |
| The International Union for Conservation of Nature rates the species Least Concern. | IUCN Red List category: Least Concern (LC). |