What Are Mustelids?

Page last updated: 21/09/2023
Global geographic range of mustelids.
Introduced range in New Zealand.

Mustelidae (pronounced: muh·steh·luh·dai) is the largest family within the order Carnivora, and also one of the most successful—with distribution on all continents save for Antarctica and Australia, as well as Madagascar and oceanic islands.(1)

Through adapting to niches in a vast variety of environments the mustelids have taken on an equally wide range of forms, while still having kept parts of the original design. Studying mustelids and how they function offers a rare glimpse into ancient times and evolution in effect.

According to current consensus, the family Mustelidae comprises eight subfamilies(2)

► Guloninae

The fisher (Pekania pennanti), tayra (Eira barbara), wolverine (Gulo gulo), and martens.

► Helictinae


► Ictonychinae

The striped polecat (Ictonyx striatus), Saharan striped polecat (Ictonyx libycus), marbled polecat (Vormela peregusna), African striped weasel (Poecilogale albinucha), Patagonian weasel (Lyncodon patagonicus), and grisons.

► Lutrinae


► Melinae

True badgers

► Mellivorinae

Ratel, a.k.a. honey badger (Mellivora capensis)

► Mustelinae

True weasels

► Taxidiinae

North American badger (Taxidea taxus)

For the record, not all are weasels

Most people know what otters are and maybe even a badger or two, but as for ferret-badgers, martens, the tayra, wolverine, etc., are all of these mustelids just weasels? Not exactly. In fact, many of these animals form their own genus and are considered distinct species in the family Mustelidae, and although this family is often loosely referred to as the so-called “weasel family”, fewer than half of the approximately 70 distinct mustelid species are weasels.

Scientifically speaking, true weasels comprises those belonging to the genera Mustela and Neogale (a.k.a. subfamily: Mustelinae).(3)(4)(5)(6) While seemingly harmless, labelling all mustelids weasels can not only potentially spread behavioural misconceptions about non-weasel species, given the historical stigma associated with the word, such a broad generalisation can also in a sense undermine the family’s evolutionary differences and unique struggles.

Some have misleading common names

With the black-footed ferret (Mustela nigripes) having “ferret” in its name despite not being an actual ferret (Mustela [putorius] furo), the fisher (Pekania pennanti) being called a “fisher cat” when it is neither a cat nor catches fish, the wolverine (Gulo gulo) being nicknamed a “glutton” when they are not particularly gluttonous, and ferret-badgers being called… well, “ferret-badgers”, it is easy to understand why so many people unfamiliar with mustelids are confused over what they are and their nature. While we understand that these are just common names and nicknames, certain misnomers (especially when used in popular culture) have contributed to a giant confusing mess with often little to no clarity for those who seek it.

To be clear, we respect cultures and do not believe in telling others what they should call an animal. However, that does not change the reality that many common names and nicknames for mustelids in English are not only confusing, they can potentially be harmful when they lead to behavioural misconceptions or mistaken identity. While scientific names are helpful for clarity, it is unrealistic to expect the average person to pay attention to them or use them in casual conversation, especially since they are not always provided in media or arguably that memorable or pronounceable. This is why regardless of the reason a mustelid was given a particular name, on this website we feel it is important to let people know certain names can be misleading, so they can be better informed and help lesson much of the avoidable confusions.

A tip regarding “American” in mustelid common names

Whatever the definition or opinion of what it means to be an American, when it comes to mustelid common names in English, it is safe to say the term usually refers to the continent of North America. This is because the often so-called American marten (Martes americana), American mink (Neogale vison), and American stoat (Mustela richardsonii) are native to both the United States and Canada, with species like the American badger (Taxidea taxus) also being native to these countries and Mexico.

Many native English speakers only associate the term American with the United States, so it can mislead some into thinking these species are exclusively native to or found in said country. Of course there would be more clarity if these species simply had North added to their common names to undoubtedly refer to the continent (or northern half of the Americas), but this is usually not the case outside of our website. However, for some reason an exception is made for Lontra canadensis, which is often called the North American river otter.

They possess anal scent glands for communication

With the exception of the sea otter (Enhydra lutris),(7) all mustelids possess well-developed anal glands that produce a strong-smelling secretion for scent marking.(8) There is a common conception that the word Mustela is in reference to this musky odour, when it probably derives from the Latin words mus (mouse) and telum (spear),(9) among other possibilities.

The term mustelid also has nothing to do with scent. In fact, despite popular belief, musk is not something that is unique to mustelids. Ever smelled a red fox (Vulpes vulpes) or lesser anteater (Tamandua tetradactyla)? When not just comparing them to dogs or cats, most mustelids are not that much muskier than many other mammals.

They make a range of sounds

Most mustelids are stealthy and rarely make noise to give their location. However, when under threat or socialising, we may hear some of their unique vocalisations. There is a tendency for some to generalise all mustelids as “dookers”, when this is far from the case. Dooking is usually in reference to the chuckling vocalisation made by an excited ferret (Mustela [putorius] furo). Other mustelids are known to make similar to considerably different types of sounds when excited such as purring/clucking/barking (martens),(10) zheeping/low trilling/chattering (wild weasels),(11) and purring/humming/barking (otters).(12) It is uncertain if these sounds are universal to species of their type.

There is more on the menu than eggs, poultry, and fish

Similar to the misconception in popular culture that mice only eat cheese and bears only honey, the diet of weasels and weasel-like species is sometimes stereotyped as only consisting of eggs, poultry, or rodents, as well as all otter species exclusively consuming fish. Many mustelids are opportunistic feeders and will eat a variety of foods depending on the season, their location, and perhaps even individual taste. The following are just a few foods certain subfamilies have been reported to consume (view our references for specific species certain foods apply to):

Melinae, Helictinae, Mellivorinae, and Taxidiinae: Amphibians, small reptiles, rodents, gastropods, invertebrates, eggs, fruits, nuts, seeds, roots, insects, mushrooms, and honey.(13)(14)(15) In the case of the ratel (Mellivora capensis), in some areas they will sometimes prey upon other small or young carnivores.(16)

Mustelinae, Ictonychinae, and Guloninae: Amphibians, small reptiles, crustaceans, invertebrates, rodents, birds, fish, moles, shrews, rabbits, hares, eggs, fruits, nuts, seeds, insects, mushrooms, honey, other small to large herbivores, and sometimes other small or young carnivores.(17)(18)(19)(20)(21)(22)

Lutrinae: Amphibians, small reptiles, crustaceans, invertebrates, fish, insects, birds, and small mammals.(23)(24)

Their struggles are often overlooked

Sometimes the constant focus on the predation habits of most mustelids in various media is not only arguably monotonous, it can also lead some people to assume that these animals have it easy and are practically invincible in the wild. Often not enough attention is given to their daily struggles.

For instance, many mustelids sometimes put their lives at risk when trying to catch a meal and can sustain a paralysing or fatal injury from their prey, or even the surrounding elements. The hunt is not always successful. Many are also prey to a number of predators such as wolves, bobcats, coyotes, foxes, and birds of prey, with humans in particular being the greatest threat to nearly all species when it comes to habitat encroachment and destruction, overhunting, road traffic accidents, unregulated fur trade, and illegal trafficking. Like most wildlife, mustelids have to be very cautious animals to survive, and the often regurgitated assertion that they are “fearless” inaccurately implies they are too foolhardily to acknowledge danger.

Some scientists believe climate change is affecting the mortality of weasel species that change white for winter due to camouflage mismatch.(25)(26) Several species are also susceptible to morbidity and mortality due to canine distemper, amyloidosis, pulmonary and gastro-intestinal helminths, and bacterial respiratory infections.(27)(28) Most mustelids also live predominantly solitary lives with the female being solely responsible for rising their young—boldly and tirelessly risking their lives for the many mouths that depend on them for nourishment and protection.

If all the above was not enough, many species have both a high basal metabolic rate (BMR) and short gastrointestinal (GI) tract. So while they may be quick and efficient hunters, the trade off is that they are metabolically inefficient and will perish if they do not eat within a few hours throughout the day.(29) For some species, they are constantly on the brink of starvation in winter.(30)


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  3. Koepfli, Klaus-Peter, Kerry A. Deere, Graham J. Slater, Colleen Begg, Keith Begg, Lon Grassman, Mauro Lucherini, Geraldine Veron, and Robert K. Wayne. Multigene phylogeny of the Mustelidae: resolving relationships, tempo and biogeographic history of a mammalian adaptive radiation“. BMC biology 6.1 (2008): 10.
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  13. Shefferly, N. 1999. Taxidea taxus (On-line), Animal Diversity Web. Accessed 22 July, 2020.
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  23. Pagacz, Stanisław; Witczuk, Julia (2010). “Intensive exploitation of amphibians by Eurasian otter (Lutra lutra) in the Wolosaty stream, southeastern Poland” (PDF). Annales Zoologici Fennici. 47 (6): 403–410. doi:10.5735/086.047.0604. S2CID 83809167.
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  28. Akdesir, E., Origgi, F.C., Wimmershoff, J. et al.Causes of mortality and morbidity in free-ranging mustelids in Switzerland: necropsy data from over 50 years of general health surveillance. BMC veterinary research 14.1 (2018): 1-19.
  29. King, Carolyn M. The Advantages and Disadvantages of Small Size to Weasels, Mustela Species”. Carnivore behavior, ecology, and evolution. Springer, Boston, MA, 1989. 302-334.
  30. Turbak, Gary. 01 February, 1992. Living Hungry. The National Wildlife Federation. Accessed 05 January, 2023.

What Are Mustelids?

Badgers | Ferret-Badgers | Fisher | Grisons | Martens | Otters | Tayra | Weasels | Wolverine