QuestionLeast weasel
What Is the Smallest Carnivore? The Least Weasel Explained
The smallest carnivore in the world is the least weasel (Mustela nivalis). The tiniest individuals, which live in North America and Siberia, weigh only about 25–60 g (0.9–2 oz), as much as two or three mice. No other member of the order Carnivora, the group that includes cats, dogs, bears and weasels, is as small.
Contents
What “carnivore” means here
The word carnivore has two meanings. In everyday speech, it means any animal that eats meat. In biology, it also names an order of mammals, Carnivora, which includes the cat, dog, bear, weasel, raccoon, mongoose, hyena and seal families. Members of this order share features such as special shearing cheek teeth called carnassials.
When biologists call the least weasel the smallest carnivore, they mean the smallest member of the order Carnivora. If you count every mammal that eats other animals, shrews win easily: the Etruscan shrew weighs only about 1.8 g (0.06 oz). But shrews belong to a different order, Eulipotyphla, along with moles and hedgehogs.
How small is the least weasel?
The least weasel varies hugely in size across its range, more than almost any other mammal. Northern populations are tiny, while those in North Africa and Central Asia can be about four times heavier.
| Least weasel population | Typical weight |
|---|---|
| North America and Siberia (smallest forms) | About 25–60 g (0.9–2 oz) |
| Britain and central Europe | Males about 100–130 g (3.5–4.6 oz); females about 55–70 g (1.9–2.5 oz) |
| North Africa and Central Asia (largest forms) | Males up to about 250 g (8.8 oz) |
Across the species, the head and body measure about 11–26 cm (4.5–10 in), and the tail is short, about 1.2–8.7 cm (0.5–3.4 in). Females are much smaller than males, so the very smallest carnivores of all are female least weasels from the far north.
How it compares with other small carnivores
Several other carnivores are famous for being small, but none comes close to the least weasel in weight.
| Animal | Family | Typical adult weight |
|---|---|---|
| Least weasel | Weasels (Mustelidae) | About 25–250 g (0.9–8.8 oz) |
| Stoat | Weasels (Mustelidae) | About 100–450 g (3.5–16 oz) |
| Common dwarf mongoose | Mongooses (Herpestidae) | About 210–350 g (7–12 oz) |
| Fennec fox | Dogs (Canidae) | About 0.7–1.6 kg (1.5–3.5 lb) |
| Rusty-spotted cat | Cats (Felidae) | About 0.9–1.6 kg (2–3.5 lb) |
| Asian small-clawed otter | Weasels (Mustelidae) | About 1–5 kg (2–11 lb) |
The common dwarf mongoose of Africa is the smallest carnivore on that continent, and the fennec fox is the smallest member of the dog family (see what is the smallest fox?). The rusty-spotted cat of India and Sri Lanka is usually named the smallest wild cat. The stoat, the least weasel’s closest look-alike, is noticeably larger and has a black tail tip; see stoat vs weasel.
Why is the least weasel so small?
The least weasel’s size is an adaptation for one job: hunting small rodents inside their homes. A weasel can pass through any hole a vole or mouse can use, roughly 2.5 cm (1 in) across, and chase its prey through burrows, under logs and inside stone walls. In winter, it follows voles and lemmings through their tunnels under the snow.
Fossils suggest weasels shrank over millions of years as grasslands spread and small burrowing rodents became abundant. Animals that could follow rodents underground had a big food supply that few competitors could reach. Small size also lets weasels survive on a single vole for a meal.
The smallest least weasels live in the coldest places, which is unusual. Many mammals are bigger in the north, but for weasels the main food in the north is voles and lemmings under the snow, and only the smallest hunters can get to them.
The cost of being tiny
Being so small has a price. A least weasel’s long, thin body loses heat very quickly, and there is little room to store fat. To stay alive it must eat about a third of its body weight every day, roughly one or two voles. It hunts by day and night in short bursts and rests in a nest lined with fur from its prey.
Small size also makes the weasel vulnerable. Owls, hawks, foxes, stoats, snakes and domestic cats all kill least weasels, and most wild weasels live only one or two years. They make up for it by breeding fast, with litters of about six kits after a pregnancy of only about five weeks.
Fierce for its size
Despite its size, the least weasel is a bold, efficient predator. It kills small prey with a quick bite to the back of the skull and can sometimes tackle animals much larger than itself, such as young rabbits and birds. When threatened, it hisses, shrieks and releases a strong musk. To learn more about how it hunts, see what do weasels eat?, and for other record-breaking small creatures, browse our list of the smallest animals in the world.
Frequently asked questions
What is the smallest carnivore in the world?
The least weasel (Mustela nivalis) is the smallest member of the order Carnivora. The smallest individuals, from North America and Siberia, weigh around 25–60 g (0.9–2 oz) and are about 11–18 cm (4.5–7 in) long without the tail.
What is the smallest meat-eating mammal?
If you count every mammal that eats animals, shrews are smaller than any weasel. The Etruscan shrew weighs only about 1.8 g (0.06 oz) and eats insects and other small invertebrates, but shrews are not in the order Carnivora.
Is a weasel smaller than a mouse?
No, but the smallest weasels are not much bigger. A tiny North American least weasel may weigh about as much as two house mice, which is why it can follow mice into their burrows.
What is the smallest wild cat?
The rusty-spotted cat of India and Sri Lanka is usually named the smallest wild cat, at about 0.9–1.6 kg (2–3.5 lb). The African black-footed cat is similarly small. Both are many times heavier than a least weasel.
What is the smallest carnivore in Britain?
The least weasel, usually just called the weasel in Britain, is the country's smallest carnivore. British males weigh around 100–130 g (3.5–4.6 oz) and females roughly half that.
Sources and further reading
- Animal Diversity Web (University of Michigan), "Mustela nivalis"
- IUCN Red List of Threatened Species, "Mustela nivalis"
- King, C. M. and Powell, R. A., The Natural History of Weasels and Stoats, 2nd edition (2007)
- Macdonald, D. W. (ed.), The Princeton Encyclopedia of Mammals (2009)
Cite this page
“What Is the Smallest Carnivore? The Least Weasel Explained.” Animal Atlas, https://animals.bigworldlist.com/questions/what-is-the-smallest-carnivore/.
