The Differences Between Ferrets & Weasels

Ferrets and weasels are similar in many ways. They're both small, furry mammals with short legs and elongated bodies. They're both carnivorous, they're both very quick on their feet, and they both belong to the Mustelidae family, part of the Carnivora order. As such, confusing the two is actually quite common, but there are major differences between ferrets and weasels

The Mustelidae group comprises stoats, polecats, mink, fishers, wolverines, martens, badgers, otters, and weasels. This is where the first major difference between ferrets and weasels occurs. While the latter form one of the species in the Mustelidae family, ferrets are part of a subspecies: the polecat branch. A ferret is actually thought to be a domesticated version of the European polecat (Mustela putorius).  

While both ferrets and weasels belong to the same mammal family, then, they are very much two separate species and differ in numerous ways, from their appearance to their habits and diet. Here are all the major differences between ferrets and weasels.

One of the major differences between ferrets and weasels is that while the former have been domesticated for 2,500 years, weasels remain wild animals. Though there is speculation as to exactly when ferrets became domesticated, there is evidence from around 500 B.C. that humans were breeding and keeping polecats. The main reason for the domestication of these small mammals was to help in hunting, with ferrets proving particularly useful for tracking down and catching rabbits and rodents. Thanks to their small, lean bodies, ferrets are adept at chasing such creatures into burrows and down small holes — which is exactly why, in 6 B.C., Caesar sent the animals to the Balearic Islands in order to get a handle on rabbit plagues.

But domesticating these creatures proved to be worthwhile beyond hunting. After ferrets were introduced to the Americas in the early 17th century, they were widely used to defend grain stores in the American West. Thanks to their ability to "ferret out" rodents, they proved to be excellent guardians of these food stores, protecting them from hungry vermin. Since then, domesticated ferrets have become an increasingly popular pet, particularly since the 1980s. It's worth noting that while ferrets are typically thought of as domesticated animals, in the United States, there is a species that lives in the wild: the black-footed ferret. This animal is native to the U.S. and was, at one point, thought to have been wiped out, before their numbers rebounded.

Weasels, on the other hand, are most certainly not domesticated. Similarly to ferrets, weasels were introduced to the U.S. in the 1880s to control rabbits, but they quickly became known as pests themselves. Like ferrets, they are predators of birds, eggs, lizards, and insects but are known for attacking and preying on animals much larger than themselves. They are also known to be aggressive and territorial, and therefore never became domesticated.

Ferrets are the largest of the mustelids, weighing between 1.3 and 2.8 pounds and growing to lengths of between 8 to 20 inches. Weasels, meanwhile, are the smallest of the mustelid family, typically weighing between 0.13 and 0.26 pounds and ranging in size from 10 to 12 inches. This is the most obvious visual difference between the two animals, but there's also the tails. Ferret tails typically reach 5 inches while weasel tails can grow to almost twice as long as the animals' body. 

The two creatures also differ in terms of their coats. The most well-known ferret coats have a black-brown coloration mixed with cream or white. But there are actually multiple different ferret colors. In fact, the American Ferret Association identifies seven different ferret colors, ranging from albino to champagne, and seven different pattern standards. Weasels, on the other hand, typically have a brown or red-brown overcoat and creamy white underbelly. The differentiation between the weasel's brown or red fur and the cream fur is typically irregular and differs from animal to animal. Weasels are very similar in their coloration to stoats, another animal in the Mustelidae family (there are, however, major differences between weasels, stoats, and ferrets). Often, the black tip on a stoat's tail is the only way to tell the two apart.

In some places, weasels actually change color for the winter season. In Pennsylvania, for example, five of every six long-tailed weasel in the north of the animal's range stay brown in winter, but one out of every six will shed its brown fur in favor of an all-white winter coat. The weasel is thought to have developed this adaptation as protection against predators. Interestingly, some long-tailed and short-tailed weasels often turn white for the winter but will keep a small black patch at the tip of their tails to distract aerial predators such as hawks or owls from targeting more vital sections of their bodies.

Ferrets and weasels are often found in the same areas, but there are differences here, too. Ferrets reside in North America, North Africa, and Europe while weasels reside in North America, South America, Asia, Europe, and North Africa. However, specific habitats differ greatly between the two creatures, with weasels demonstrating much more adaptability than their Mustelid cousins. They can typically be found in woodlands, marshlands, moors, and grasslands but have also been found in more urban areas. The weasel will build a den in tree roots, hollow logs, under rocks, and even in rodent burrows, and will typically make their den a foot or so below ground. They also use dry vegetation, fur, and feathers to line the walls of their dens, which are then used to store food alongside providing shelter for the weasels.

In North America, the black-footed ferret has adaptations that make it the only ferret that usually lives in the wild. These animals live in burrows created by prairie dogs, which also keep them protected from aerial predators. They typically prefer grasslands and prairies, and survive on a healthy supply of prairie dogs. Otherwise, ferrets are domesticated animals, and are quite happy living in homes with their owners.

A major difference between ferret and weasel behavior is that the former are naturally crepuscular creatures, while weasels are not. That means ferrets are naturally active at dawn and dusk but otherwise sleep between 18 and 20 hours a day. However, since most ferrets are domesticated, they will actually adapt their schedules to their owners' routines, which means they can't be easily categorized as crepuscular, nocturnal, or diurnal. Essentially, ferrets are essentially happy to wake up and play whenever their owners are available. 

By contrast, weasels are both diurnal and nocturnal depending on the seasons. The animals don't hibernate, which means they remain active throughout the year, and while they are thought to be mainly nocturnal, certain times of the year, such as summer, will see them become more active in the daytime. Since they are domesticated, ferrets don't need to worry about hunting, but the wild black-footed ferret maintains a mainly nocturnal schedule, emerging from their burrows for just a few minutes during the early morning to hunt, find a new burrow, or mate.

In terms of diet, both weasels and ferrets are carnivores, but weasels are much more prolific in terms of the animals they hunt. These smaller mustelids eat everything from mice, voles, and rabbits to ducks, chickens, frogs, and fish. Weasels are also one of the animals that eat turtles, have been known to dine on hedgehogs, and even eat the eggs of their prey. Because they are such long animals and lose a lot of body heat, weasels actually need a lot of food to survive, and must eat roughly one-third of their body weight every day. Luckily, they are extremely adept hunters that have been known to take down animals much bigger than themselves, and store remains in their dens. 

Ferrets, having been domesticated for thousands of years, are well and truly catered for. Though they are obligate carnivores, there are plenty of dry food options produced for owners to feed their pets. The black-footed ferret, meanwhile, basically subsists on prairie dogs, which make up 90% percent of their diet. They also eat smaller animals such as mice, rats, squirrels, rabbits, and birds. 

A domestic ferret can expect to live for between five and seven years, while black-footed ferrets live for roughly four to five years. Lifespans of weasels differ more dramatically, however. In the U.K., weasels have a life expectancy of roughly two years while the long-tailed weasel is listed as having a lifespan of roughly five years. Elsewhere, the National Wildlife Federation states that weasels have life expectancy of just 18 months. What's more, life expectancy for weasels can differ between females and males, with the former often living longer than their male counterparts simply by virtue of the fact they are less likely to travel further to search for a mate, thereby giving predators less of a chance to strike.

Some weasel populations are also under threat. In 2021, the BBC reported on the dramatic decline of weasels in the U.K., with their numbers falling by half over the previous 50 years. Otherwise, weasel numbers in North America remain stable.

Domestic ferrets don't have any kind of conservation status, but sadly, the black-footed ferret is one of the most endangered mammals in North America. Though they were once thought to be extinct, their numbers rebounded after several were captured and bred before being reintroduced into the wild. However, the creature is now facing multiple threats such as habitat loss and disease.