There are over 50 species worldwide in the Mustelidae family. In North America, there are only 11 species.
- American Badger
- American Marten
- American Mink
- Black-footed Ferret
- Least Weasel
- Long-tailed Weasel
- River Otter
- Sea Otter
The family of Mustelidae consists of some of the most diverse groups of carnivores; however, they have similarities.
Male members are generally larger than females. Their fur is either spotted, striped, or colored.
Most family members’ bodies are generally long and thin, although the wolverine and badger are more extensive and stockier. Most species have short ears and limbs.
Mustelids are diurnal or nocturnal and live in crevices and caves. Many members of the family sit up to look around.
Being carnivores, mustelids mainly eat other animals. Some occasionally feed on plants, and some are omnivorous. They have great senses of sight and hearing but hunt by smell.
Mustelids have anal glands that secrete in a defensive measure. Skunks were once members of this family but have now been recategorized.
Mustelids have been around since the early Oligocene in North America.
The American badger is one of many carnivorous North American mammals. Its color is dark gray with a white stripe on its back, white patches on its eyes, and a white underbody.
The American badger measures from 60 to 75 cm and weighs from 6.3 to 8.6 kg. This carnivore eats mice, squirrels, groundhogs, moles, marmots, and prairie dogs.
They live in grasslands, prairies, marshes, and farms. Their lifespan is four to fourteen years in the wild and twenty-six in captivity.
The American marten is a small, solitary, and nocturnal member of the Mustelidae family.
Their color ranges from yellowish-brown to black. They measure 32 to 54 cm and weigh from 0.5 to 1.3 kg.
The American Marten eats smaller animals such as squirrels, birds, and mice but will also eat fruits and nuts.
They are widely scattered in northern, mature conifer forests throughout the continent. They can be found on the ground and in trees, with an estimated lifespan of fewer than fifteen years.
The American mink can be found in the northern regions of North America. The color varies from brown to black, with a white patch on the throat.
They measure from 31 to 45 cm and weigh 400 to 1580 g. Their lifespan is three to four years in the wild and ten years in captivity.
American mink are carnivores eating muskrats, snakes, mice, fish, rabbits, chipmunks, birds, and frogs. They live in wet areas like swamps and marshlands or near water bodies.
The black-footed ferret is also referred to as the American polecat or prairie dog hunter. They are a mustelid species native to North America and listed as endangered animals.
They were previously considered extinct, but a captive-breeding program successfully reintroduced this species to their native habitat.
Their body length is between 500 to 533 mm with a tail of 114 to 127 mm, and they weigh between 650 to 1400 grams.
They have slender and long bodies with black feet, ears, tails, and part of their faces. Their neck is long, and they have stout, short legs.
Their pelage is yellowish-blond. The black-footed ferret is nocturnal and solitary. They feed mainly on prairie dogs, which they hunt in their burrows.
The ermine is a solitary weasel in the continent’s northern part.
Their color is dark brown on the back and white on the underbody during the summer. In winter, their color changes to almost pure white.
The ermine measures from 17 to 32 cm and weigh about 260 g. The ermine is a carnivore that mainly eats rodents, birds, fish, amphibians, small reptiles, and insects.
They live in taigas and tundras, with a lifespan of four to six years in the wild.
The fisher is a small, solitary, mainly nocturnal, aggressive, and elusive weasel. They are related to the American marten.
Their color varies from dark brown to black, with a lifespan of seven years in the wild and, in rare cases, up to 14 years in captivity. They measure from 75 to 120 cm and weigh 2 to 6 kg.
The fisher is a carnivore that eats mice, snowshoe hares, birds, cats, poultry, shrews, porcupines, and squirrels.
Even though they move on the ground most of the time, they are also excellent climbers.
They live in forests in the southern part of Canada and the northern and western parts of the United States.
The least weasel is also known as the common weasel or little weasel. They are the smallest member of the genus Mustela.
They are native to North America but also Eurasia and North Africa. Their bodies are slender and elongated, with relatively short tails and legs.
The average body length is around 130 to 260 mm, and they weigh 36 to 250 grams, with males slightly more significant than females.
The color of the least weasels’ pelage varies according to the geographical location, but the underparts are usually white, and the back, limbs, and tail are brown.
Their diet consists mainly of small rodents. Males mark their territory with olfactory signs and are strongly territorial and dominant weasels.
Least weasels may have aggressive encounters with each other. The least weasel occupies a wide range of different habitats.
The long-tailed weasel is a fearless, aggressive hunter. They are also known as the bridled weasel or the big stoat.
Their color is reddish-brown with a light yellow underbody, but they are entirely white in cold northern regions.
The long-tailed weasel measures 23 to 35 cm and weighs 85 to 267 g. They are carnivores and can attack animals that are twice their size.
They eat primarily mice, voles, rabbits, chipmunks, birds, eggs, and insects.
They live in grasslands and thin forests in sub-tropical areas with mild temperatures in the southern states of North America. Their lifespan is up to five years.
Are weasels dangerous to pets? What do they eat? Please find out more in this article I wrote.
Northern River Otter
The river otter is an intelligent, semiaquatic mammal in the northern states.
The river otter has short, very dense fur. Their colors vary from gray to brown, with a lighter underbody.
They measure from 66 to 107 cm and weigh 5 to 14 kg.
River otters are carnivores eating fish, turtles, frogs, crayfish, and insects.
They live in aquatic habitats in the northern part of North America. Their lifespan is eight to nine years in the wild and fifteen to twenty years in captivity.
The sea otter is a mammal on the northern and eastern North Pacific Ocean coasts. They usually weigh between 14 and 45 kilograms and are about 1.2 to 1.5 meters in total body length.
They are considered the most prominent members of the weasel family but are among the smallest marine mammals.
Their primary form of insulation is a thick coat of fur, and they can live exclusively in the ocean.
They feed primarily on marine invertebrates such as urchins, mollusks, crustaceans, and fish species.
In the past, sea otters were hunted extensively for their fur, which significantly decreased their population. However, conservation efforts and reintroduction programs have successfully re-establish sea otters’ presence in their natural habitat. They are still listed as endangered species.
Their pelage is usually brown. Diurnal animals tend to rest together in single-sex groups called rafts. A raft might contain from 10 to 100 individuals. Male rafts are generally more prominent than female ones.
They can be found in areas protected from the most severe ocean winds, such as rocky coastlines and barrier reefs.
The wolverine resembles a small bear but is the most prominent member of the Mustelidae family.
They are ferocious and have tremendous strength for their body size. They are the size of a medium dog but can take down prey many times their size, such as elk.
They live in cold climates, with thick, oily fur resistant to frost. They are dark in color, with a light mask on their face and a bushy tail.
They have been called the skunk bear due to the scent glands to mark their territory.
Bryan Harding is a member of the American Society of Mammalogists and a member of the American Birding Association. Bryan is especially fond of mammals and has studied and worked with them around the world. Bryan serves as owner, writer, and publisher of North American Nature.