Weasels and related mammals
Weasels and related mammals belong to the family Mustelidae, which is part of the order Carnivora. This diverse family includes a variety of species such as weasels, otters, skunks, badgers, and wolverines, totaling around seventy species worldwide, except for Antarctica, Australia, and the Sahara Desert. Mustelids are adapted to various habitats, from Arctic regions to tropical rainforests, and exhibit a range of physical characteristics, including long, slender bodies and sharp claws for hunting and burrowing. Their diet is primarily carnivorous, with many species known for their proficient hunting skills and distinct musk used for marking territory and self-defense.
Some notable members include the black-footed ferret, which is endangered in North America, and river otters, known for their playful nature. Skunks are easily recognized by their striking black and white fur and potent defensive spray, while badgers are burrowing specialists with robust bodies. Wolverines are powerful animals that can take on prey much larger than themselves. Conservation efforts are in place for many mustelid species, reflecting concerns about their survival due to habitat loss and hunting pressures. Overall, mustelids are fascinating creatures with unique adaptations that contribute to their roles in various ecosystems.
Weasels and related mammals
Mustelid Facts
Classification:
Kingdom: Animalia
Subkingdom: Bilateria
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Carnivora
Family: Mustelidae
Subfamilies: Mustelinae (weasels and allies, ten genera, thirty-three species), Mephitinae (skunks, three genera, thirteen species), Lutrinae (otters, six genera, twelve species), Melinae (badgers, six genera, eight species), Mellivarinae (honey badger)
Geographical location: Worldwide, except Antarctica, Australia, and the Sahara
Habitat: From the Arctic to tropical rainforests; most live on the ground, some live in trees, and still others inhabit rivers or oceans
Gestational period: From one to nine months
Life span: From one to up to twenty-five years
Special anatomy: Paws with sharp digging and grasping claws, luxurious fur, webbed feet in otters
About seventy species belong to the weasel family (Mustelidae). These furry mammals weigh from three ounces (85 grams) to 100 pounds (45 kilograms) and make up the largest family in the order Carnivora. Included are weasels, minks, martens, wolverines, otters, skunks, and badgers. Mustelids live worldwide, except for Antarctica, Australia, and the Sahara Desert. Their habitats range from the Arctic to tropical rainforests. Some live on the ground, others live in trees, and still others inhabit rivers or oceans.
Most weasel family members have long, slender bodies and all have short legs. Each mustelid paw has five toes, with sharp claws for grasping prey and burrowing. The smallest mustelids, least weasels, weigh three ounces. River otters, the largest mustelids, are four to six feet long (with tails) and weigh up to seventy pounds. Sea otters can weigh ninety to one hundred pounds. Beautiful, luxurious mustelid fur is sought for use in fur garments.
All mustelids have perineal glands which make unpleasant-smelling musks, causing their characteristic odors. Musks mark territory or are used for self-defense. The odor of mustelid musk is most offensive in skunks, which use it for self-defense.
Male and female mustelids often live alone, except when mating. Mating seasons vary with species and habitat. Pregnancy for mustelids ranges from one to nine months. Litters contain one to ten young, depending on species and food availability. Life spans of mustelids that reach old age are one to twenty-five years.
Weasels
Weasels, like most mustelids, are carnivores. They eat other animals, carrion, and insects. All weasels have keen eyesight, keen smell, and are excellent hunters. They are bloodthirsty, often killing for fun and leaving prey carcasses uneaten. Humans hunt weasels in response to their bloodthirsty natures and for their beautiful, soft fur. This is especially true of weasels that live in cold climates and grow white winter coats that collectively provide ermine.
Weasels are known for their unpleasant odor, from musk made in perineal glands. The long-tailed weasel is the best-known North American species. It has a white belly, a brown back, and a black tail tip. Males and females are 1.5 and 1 foot (45 centimeters and 31 centimeters) long, respectively. The least weasel, also North American, is the smallest known carnivore, only six to eight inches (15 to 20 centimeters) long.
Martens and Fishers
Martens are carnivorous mustelids, genus Martes. They occur in northern forests of the eastern and western hemispheres. Martens are long and graceful, with short legs and sharp-clawed toes. They live in hollow trees and take over woodpecker or squirrel holes. They eat rabbits, squirrels, birds, mice, eggs, and carrion. They mate in July and August. Nine months later, one to five young are born.
The most common North American marten is the pine marten (American sable). Pine martens are most plentiful in the northern Rockies, Canada, and Alaska. They also occur as far south as the Adirondacks, and west to Colorado. A pine marten is twenty-four to thirty inches long, including a six-inch (15-centimeter) tail. Its brown fur is thick and soft, with orange or white throat and chest patches. Pine martens are hunted for their valuable fur. Their enemies are lynx, owls, and humans. Similar animals, the baum and stone martens of Europe and Asia, have yellow and white throats, respectively.
Another important marten is the fisher, a pine marten subspecies and the largest of martens. Fishers are 4.5 feet (137 centimeters) long, including 16-inch (41-centimeter) tails, and weigh up to 15 pounds (seven kilograms). Their luxuriant fur is medium to dark brown, with gold or silver head and shoulder tops and creamy chest patches. Fisher fur is also quite valuable. The fisher habitat range is like that of pine martens, but not as far north. Fishers are the only animals that kill and eat porcupines without being hurt. Otherwise, their diets are like those of other martens.
Otters
Otters are mustelids that live mostly in water, either in rivers or oceans. River otters are found worldwide, except for Australia, New Zealand, and Antarctica. River otters of Europe, Asia, and North America have thick, four-foot-long, flexible bodies and tails about two feet long. Otter heads are broad and flat, with round ears and blunt snouts. Their nostrils are closed when diving. Beautiful otter fur is dark brown and desired for fur garments. As in other mustelids, otter legs are short. Otter feet are both webbed and powerfully clawed.
River otters live in waterside dens with underwater entrances. Their gestation period of two months produces two to three offspring, which stay with their mother for a year. These otters are rapid swimmers and expert divers. They eat fish, crayfish, snails, shellfish, frogs, insects, birds, and small water animals. River otters are friendly and playful.
Sea otters inhabit the Pacific coasts of Asia and North America. They live mostly in the water. Sea otters are 2.25 to 4 feet (76 to 123 centimeters) long and live on a diet of sea urchins, crabs, snails, and shellfish. They have one or two offspring per litter. Red-brown to black sea otter pelts may cost over two thousand dollars each. Sea otters have been so hunted that they are very cautious. They are protected species in US waters.
Skunks
Skunks are found throughout the United States, in Mexico, and in southern Canada. Cat-sized, these stocky mustelids have long, pointy noses, arched backs, and short legs. Skunk fur is long, thick, shiny, and black, with white stripes down the back. Stripe patterns differ among species. Skunks have white forehead patches and long bushy tails, black on top and white underneath. Striped (common) skunks have long black fur and white stripes running from head to tail. They breed in late winter or early spring and have three to five offspring, after a 2.5-month gestation. Offspring suckle for two months, and then their mother teaches them to hunt.
Skunk self-defense uses paired perineal glands on either side of its anus, near the tail. These glands are found in all other mustelids. In skunks, they are relatively large and contain terrible-smelling liquid musk. Frightened skunks squirt musk distances up to twelve feet (four meters). The horrible odor keeps enemies away. Animals that are sprayed smell bad for days. Skunks inhabit hollow trees or burrows and eat rodents, birds, lizards, eggs, insects, honey, and bees.
Badgers
Badgers are two-foot-long mustelids with short, strong legs, squat, broad bodies, and forelegs having claws that are efficient burrowing tools. They are nocturnal, heavily furred, and very strong. Badgers live in deep burrows on and in prairies, woods, or hills. Like other mustelids, they have perineal glands which make fetid musk. Their pelts are valued garment furs. American badgers are found in western North America, east to Ohio and north to southern Canada. Their shaggy fur mixes gray, black, and brown hair. They eat field mice, squirrels, and gophers, digging animal prey out of underground homes.
European badgers are like American badgers in size and color, but have teeth designed for omnivorous diets. They live in forests in deep burrows, and their litter size is four or five young. These badgers eat fruits, nuts, eggs, birds, rodents, frogs, snails, worms, and insects, and love honey and wasp or bee larvae. Shaggy hair protects them from being stung. All badgers are quarrelsome. Caged together, they fight continually. They are also very brave and fight savagely, if cornered.
Wolverines
Wolverines are mustelids of the genus Gulo. They are among the most powerful animals of their size. Wolverines live in the northern woods of North America, Europe, and Asia. They have long, tapering heads, heavy 2.5-foot-long bodies (76 centimeters), bushy 8-inch tails (20 centimeters), short legs, and large feet with sharp claws. Wolverine teeth are long and sharp. Their powerful jaws can crush the bones of prey. Wolverines look like small bears, and their dark, white-marked pelts make fine fur garments. This has made them rare, after ruthless hunting. Males and females can weigh 55 and 30 pounds (25 and 14 kilograms), respectively.
Wolverines are solitary, except for mating in spring and summer. Nine months later, females give birth to around four offspring. Offspring nurse for ten weeks and stay with their mothers for a year. Wolverines do not stalk or chase. They pounce from trees or rocks and kill animals much larger than themselves, such as reindeer. Wolverines also eat smaller animals, birds, and carrion. Wolverine predators are bears, pumas, and humans. When attackers get near wolverines, they spray smelly musk. If this warning does not work, the wolverines fight attackers fiercely.
Mustelid Preservation
Several animal protection groups, such as the World Wildlife Fund and Friends of Animals, have long feared that many animal species will soon be extinct and that making and wearing fur garments is cruel. Thanks to their actions, the US Congress passed an Endangered SpeciesConservation Act (1973) and its convention (1977). Therein, the United States and eighty other nations designed ways to control and monitor the import and export of fur of imperiled species. Endangered species were defined as in danger of extinction, while threatened species are likely to be endangered soon. Among the covered animals are otters and badgers. Other mustelids may be added soon. Under the act and convention, participant countries must stop fur movement in intercountry or interstate commerce unless they have proof that species involved are not threatened or endangered. In 2024, six species of mustelid were listed as vulnerable, seven were listed as endangered, one, the European mink, was listed as critically endangered, and the sea mink was listed as extinct.
Principal Terms
Carrion: Dead, partly decomposed animal bodies
Ermine: Valuable white fur made from weasel pelts taken in winter
Gestation: Time period for carrying developing mammalian offspring in the uterus
Musk: Bad-smelling liquids animals make to mark territory or for self-defense
Omnivorous: Able to eat both plants and animals
Perineal: Located between scrotum and anus in males or the equivalent region in females
Bibliography
"15 Animals Similar to Weasels." Nature Nibble, 5 Apr. 2022, naturenibble.com/animals-similar-to-weasels. Accessed 9 Oct. 2024.
Hirschi, Ron, and Galen Burell. One Day on Pika’s Peak. Dodd, Mead, 1986.
King, C. M., and Roger A. Powell. The Natural History of Weasels and Stoats: Ecology Behavior and Management. 2nd ed. Oxford University Press, 2007.
Kollias, George V., and Jesus Fernandez-Moran. "Mustelidae." Fowler's Zoo and Wild Animal Medicine, Volume 8, 2015, pp. 476-491. ScienceDirect, doi.org/10.1016/B978-1-4557-7397-8.00048-7. Accessed 9 Oct. 2024.
MacQuitty, Miranda. Discovering Weasels. Bookwright Press, 1989.
Ward, Hannah. "Are Weasels Rodents?" A-Z Animals, 13 Apr. 2022, a-z-animals.com/blog/are-weasels-rodents. Accessed 10 July 2023.
Wright, Patrick G. R., et al. "A Global Review of the Conservation Threats and Status of Mustelids." Mammal Review, vol. 52, no. 3, 2022, pp. 410-424. Wiley Online Library, doi.org/10.1111/mam.12288. Accessed 9 Oct. 2024.
Wund, Matt. “Mustelidae.” Animal Diversity Web, animaldiversity.org/accounts/Mustelidae/. Accessed 9 Oct. 2024.