Are Weasels Rodents or Mustelids? How Are They Classified?

Weasels are little mammals with short legs, small heads, and long necks and bodies, and they can be found all over the world.

Weasels are not rodents, they are related to minks, ferrets, polecats, and ermine (all Mustela genus members) and belong to the Mustelids family (together with wolverines, otters, and badgers).

Due to their small size and appearance, weasels are often confused with rodents. In this article, I give a breakdown of their classification, and will explain what a rodent and mustelid is, and what are the main differences.

What Is a Rodent?

Rodents are mammals with lower and upper pairs of constantly growing incisor teeth. Their powerful and roughly divided masseter muscles connected to their skull and jaw in different orders provide gnawing and chewing power. They constitute about half the number of all mammal species and can be found in every continent except Antarctica.

This large order of animals comprises 27 families, including the mice and rats (family Muridae) and diverse groups like the marmot, chinchillas, beavers, porcupines, pocket gophers, and squirrels.

Rodents may be nocturnal, diurnal, or often active part of the night and day. Although a few species are herbivorous, most diets include animal and vegetable matter. Others are specialized predators of arthropods and vertebrates.

They can eat food where gathered or carry them to burrows for storage. Species living in oceanic islands and arid habitats are able to get their water needs from their food. These mammals may be active throughout the year or enter dormancy periods or deep hibernation.

What Is a Mustelid?

Mustelid is a family (Mustelidae) of carnivorous mammal species, including ferrets, martens, the wolverine, badgers, skunks, polecats, and the weasel family. These fur-bearing carnivores inhabit aquatic and terrestrial regions throughout the globe, except Antarctica, Australia, and oceanic islands.

Most mustelids are small. The smallest weasel measures about 4 to 10 inches and weighs about 25 grams is the smallest mustelid. Sea otters are the largest at about 3 feet long and weighing between 25 and 45 kg.

Most mustelids have long tube-shaped bodies, a small head with a thick neck, and short legs. They also have powerful anal scent glands, and the five digits of each foot come with sharp non-retractile claws. Females are usually smaller than males; some female weasels are not up to half the male size.

Although mustelids are carnivorous, a few add plant matter, mostly berries or fruits, to their diet. They have sharp premolars and molars and strong canine teeth. A few of them have specialized diets. Clawless otters specialize in mollusks and crustaceans, whereas other otters primarily feed on fish.

Mustelids are usually solitary except for sea otters, Eurasian badgers, and a few northern river otters. Association between females and males of solitary species during the mating period is brief. Most species reproduce annually, except the least weasel (two litters annually).

Are Ferrets and Weasels Related?

Ferrets and weasels are two identical animals that are confusing to differentiate unless you take a very close look. They are closely related (cousins), and both have long tubular body lengths, although in varying dimensions.

They both belong to the Mustelidae (parental scientific name)—weasels are among the ten species under this order, while ferrets belong to the polecat subspecies (from the Mustelid family).

Weasels have longer tails with long bodies, though their bodies are not as long as the ferrets’ (with 24-inch body length and up to 5-inch tail).

Ferrets hunt during the night, while weasels hunt mostly during the day. Weasels are hardly used as pets because of their aggressive behavior, while ferrets have been domesticated for more than 2000 years.

These creatures are carnivores; hence, they can eat small animals, including snakes, birds, rats, rabbits, mice, and more. They also both have thick furs and are very quick to enter small openings while hunting for prey.

Members of the Weasel Family

Weasels belong to the Genus Mustela family, which includes 17 species. Here are the members of the weasel family:

• Amazon weasel and tropical weasels (Mustela africana) from northern South America
• Mountain weasels (Mustela altaica), are mostly found in montane forests in Asia
• Colombian weasels (Mustela felipei)
• Long-tailed weasels (Mustela frenata) are the largest weasels found in North America. They have delayed implantation and white coats during winter.
• Japanese weasel (Mustela itatsi)
• Yellow-bellied weasels (Mustela kathiah) common in Asia
• Indonesian mountain weasel/Java weasel (Mustela lutreolina)
• Least weasels (Mustela nivalis) are the smallest weasels, mostly common in European forests and northern Africa.
• Malayan/bare-footed weasels (Mustela nudipes), mostly found in the tropical forests of Asia.
• Egyptian weasels (Mustela subpalmata)
• Back-striped weasels (Mustela strigidorsa)
• Siberian weasels (Mustela sibirica)

Other Mustela genus species are relatively larger than the true weasels. They include the endangered and rare black-footed ferret, the ferret or polecat, and the Eurasian mink.

Wrapping Up

Weasels are not rodents. They’re small mammals closely related to ferrets but with different physical looks and behaviors.