What Are Mustelids?

Global range of mustelids

For starters, not all are weasels

Most of us know what otters and badgers are, but as for martens, polecats, the tayra, American mink, wolverine, etc… Why are there so many different names for a “weasel”? That’s because many of these animals form their own genus and distinct species, most of which—despite being members of the loosely termed  “weasel family”—aren’t truly weasels at all. Technically, weasels are their own subfamily of the genus Mustela,(1) so the term “weasel” can be somewhat of a generalised misnomer when casually applied to every mustelid; undermining the family’s evolutionary differences.

A brief history

Mustelidae is the largest family within the order Carnivora and also one of the most successful, with distribution on all continents except Antarctica and Australia, as well as Madagascar and oceanic islands.(2) They’re also among the most primitive, having been around for some 15 million years and undergone few anatomical changes from the first carnivorans that appeared about 40 million years ago. This does not by any means indicate they underdeveloped—on the contrary, 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.

Clever, feisty and incredibly diverse


They possess anal scent glands for communication

With the exception of the sea otter (Enhydra lutris),(3) all mustelids possess well-developed anal scent glands that produce a strong-smelling secretion for sexual signaling, identification, defense, and marking territory.(4) There’s a common misconception that the word “Mustela” is in reference to this musky odour, when it actually derives from the Latin words mus (mouse) and telum (spear).(5)

They make a range of sounds

Mustelids are very stealth animals and rarely make noise to give their location. However, when under threat or socialising, we may hear some of their unique vocalizations. There’s a tendency to stereotype all mustelids (particularly those that are weasel-like) as “dookers”, when this is far from the case. “Dooking” refers to the chucking vocalization made by an excited domestic ferret. Other mustelids are known to make similar to considerably different types of sounds when excited such as purring/barking (martens), zheeping/low trilling (weasels), and purring/squealing (otters).

More than just predators

We often hear mustelids being described as super predators, but where is the attention to them also being super mothers? These animals will go above and beyond to provide for their young; boldly and tirelessly risking their lives for the many mouths that depend on them for nourishment. Not only that, but they also must pass down their experience to their young, so they too will have the skills needed to survive. Another overlooked fact that is that many of the smaller mustelids are prey to a number of larger predators such as wolves, bobcats, coyotes, foxes, and birds of prey.

  1. Koepfli, Klaus-Peter, et al. “Multigene phylogeny of the Mustelidae: resolving relationships, tempo and biogeographic history of a mammalian adaptive radiation.” BMC biology 6.1 (2008): 10.
  2. Wund, M. 2005. Mustelidae (On-line), Animal Diversity Web. Accessed December 30, 2020.
  3. Kenyon, Karl W. (1969). The Sea Otter in the Eastern Pacific Ocean. Washington, D.C.: U.S. Bureau of Sport Fisheries and Wildlife. p. 4.
  4. Hutchings, Michael R., and Piran CL White. Mustelid scent‐marking in managed ecosystems: implications for population management. Mammal Review 30.3‐4 (2000): 157-169.
  5. King, Carolyn M., and Roger A. Powell. The natural history of weasels and stoats: ecology, behavior, and management. Oxford University Press, 2006.

American Mink | Badgers | Ferret-Badgers | Fisher | Grisons | Martens | Otters | PolecatsTayra | Weasels | Wolverine