Midwestern Mammals

All photos by Old Naturalist, unless noted

Download the Minnesota Mammals Activity. Answer the questions using the text below. MammalsStudentActivitySheet

Timber Wolf


Timber Wolf
photo by Alli Wade

The timber wolf is gray in color and is the size of a huge German shepherd. Wolves have a sense of smell 100 times stronger than humans.Wolves were once found throughout the United States, but were shot and trapped for over 200 years. In 1849, wolf bounty hunters were paid $3 per kill. Wolves are now restricted to a few remote areas of our country (northern Minnesota, Wisconsin, Wyoming, Montana and Alaska. The wolf population in Minnesota was as low as 750 animals in the 1950’s. In 1974, the timber wolf was declared an endangered species and given full protection. By 2009, the population had increased to over 3,000 wolves in our state and the wolf has been removed from the endangered species list.

Timber Wolf photo by Alli Wade

Timber Wolf
photo by Alli Wade

Wolves live in packs consisting of a dominant adult pair and family members of different ages. There is usually ten wolves in a pack. A wolf pack range (area they live in) may be over 150 square miles. Usually only a single pair of wolves will breed in the pack, so that their territory does not get over-populated.

In Minnesota, the main food of wolves is deer and moose. In summer, they eat other prey including beaver, mice and some wild fruits.

Red Fox

Red Fox

Red Fox

Red Fox are found throughout Minnesota in brushy woodland areas, as well as wetlands. They have few natural enemies and their population in Minnesota is high. Red fox weigh slightly more than a cocker spaniel (approx. 15 pound).

Fox are active during the winter. They do not hibernate. They develop a long winter coat, and fur even covers their paws to protect their feet from the cold.

            Fox pups photo by Steve Gordon

Fox pups
photo by Steve Gordon

The breeding season begins in February and the pups are born in May (four to ten per litter). Red fox keep the same mate throughout their life. Pupping season is the main time of year when foxes use their dens. The opening to the den is 10 inches. The burrow to the nest is 20 feet long and may get up 40 feet long. The nests consists of a single room
A fox’s favorite food is rabbits and mice. Their diet also includes pheasants, chipmunks, woodchuck, squirrels, and rats. Insect make up a part of a fox’s diet including, crickets, beetles, and grasshoppers. In the summer, they will also eat berries. Fox are capable of hearing a small mammal digging underground and will dig in the dirt or snow to catch their prey. Also, fox stalk their prey and get as close to them as possible before pouncing or chasing.

Black Bear

              Black Bear www.revelstokebearaware.org

Black Bear

Black bears are the largest carnivores in Minnesota, usually weighing 250-300 pounds. Black bears originally were found throughout Minnesota, but were killed off in southern Minnesota, but now occur in the northern forests. In 2008, the Minnesota DNR estimates that there 25,000 black bears living in Minnesota woods. The black bear population is stable in Minnesota, even though 3500 of them are killed by hunters each year.

Only 10 % of a black bear’s diet is meat. It is omnivorous eating both meat and plant material. Black bear feed on grasses, fruits, berries, buds, nuts, insects and dead things.

Black bears mate during the summer months and give birth during the winter months, while they are hibernating. Two cubs are the most frequent number in a litter, but there may be as many as five. At birth, a cub is hairless and weighs less than a pound. It will not open eyes for a month. But by the fall of their first year a rapidly growing cub will weigh 60 to 100 pounds. A black bear den may be in a tree, rocky crevices, or a hole that the bear dug.

Black bears usually try to avoid humans. But they can sometimes be a nuisance by getting into garbage, breaking into cabins or getting into a camper’s food. However, there are only three known attacks by black bears in Minnesota, and none of them were fatal.


Muskrat climbing on cattail house

Muskrat climbing on cattail house

Muskrats are rodents and larger than a cat. They have long hairless tails that they use for swimming. Trappers have hunted muskrat for their soft fur.

They build little beaver-like huts out of cattails and a family will spend the winter inside of it. Muskrats also dig out bank dens and live at the edge of ponds and rivers.

In the fall, muskrats start storing roots and underwater plants on the bottom of the pond where they live. In the winter, they remain active and swim beneath the ice from their den to their storage caches (where food is stored).

Female muskrats give birth to over a dozen young. The family spends the winter in the den. The following spring,
the young leave the shelter of their home and look for a new territory. It is at this time that many muskrats are hit by cars on highways.

Muskrat on cattail hut


The main enemies of muskrats are fox and mink. A mink will dig out a muskrat burrow, kill and eat all of the rats inside, then stay in the hut until it is ready to move on.


A groundhog feeding in early Spring.

A groundhog feeding in early Spring.

Groundhogs or woodchucks are rodents and are actually Minnesota’s largest squirrel. Although they are usually found on the ground, they can also climb trees. They are dark, plump and have skinny little tails.
Groundhogs are Minnesota’s longest hibernator. They go into their burrows in October with a lot of fat and they do not store any food to eat during the winter. While in hibernation, a groundhog breathes once every six minutes; the heart rate slows to 4 beats a minute; and the body temperature drops to 38° F.

Their woodland den is often on a hill and has a five inch opening. Groundhog day is February 2nd, but Minnesota’s groundhog does not emerge from its den until mid-March. When it finally does come out and start feeding, it has lost almost 40% of its weight in fall.


Beaver2Beavers are the largest rodent in North America, weighing up to 72 pounds. Their bodies are specialized for living in the water, since they have thick fur, a large flatten tail, and powerful hind feet that are webbed.

Beavers may have affected human history in North America more than any other wild mammal. In many cases, pioneer settlement of an area was based upon trapping beaver for the fur trade. In the 1800’s beaver skin hats were very fashionable in Europe and beaver were trapped to near extinction in Minnesota. However, beavers are survivors, and their populations have recovered.

Beaver feeding on water lily roots

Beaver feeding on water lily roots

Beavers mate for life and one family, adults and juveniles, lives together in a large lodge in the water. The lodge can measure 15 feet high and 40 feet across. Beavers are active all year round, swimming beneath the ice in the winter and feeding on sticks and branches stashed on the bottom of the beaver pond. Beavers must be able to hold their breath for several minutes as they swim from the lodge to the storage area and back.

Beavers also live in bank dens when the conditions are not right for a lodge. A bank den may be dug out over 20 feet away from the water.

In the summer, beavers feed on water plants including water lilies and trees close to shore. In the winter, they survive on freshly cut green trees that are stored beneath the water. Aspen, poplar and willow are commonly cut by beavers. An adult beaver can chew through a 6 inch tree in 15 minutes.

Many people do not like them because beaver dams tend to flood their property. But beavers are responsible for improving the wildlife habitat for many types of animals including: fish, ducks, muskrats, mink, moose, frogs and otters.




The chipmunk is easily identified by the two stripes that are on the back and over the eyes. Chipmunks also have cheek pouches, so they can carry extra food they have gathered (up to 70 sunflower seeds have been found in its cheek pouches). Chipmunk gets its name because in the spring they make a “chip” call, and in the fall, they make a “munk” call.

Chipmunks are found in wooded areas. Their burrows have a two inch wide opening and have long runways which gradually descend to 2 feet deep. The burrow consists of a nesting area and several food storage areas, as well as a toilet area. A chipmunk burrow has been found to hold over 10 quarts of food stored for winter survival. Chipmunks spend from November to March in their burrows. They usually sleep for 3-4 days, get up and eat and then go back to sleep.

Chipmunks eat mostly seeds and berries, including: acorns, sunflower seeds, and raspberries. In the summer, they eat grasshoppers and other insects.

Its enemies include: garter snakes, owls, hawks, foxes, mink and weasels.

Red Squirrel

Red Squirrel on a cold winter day (Aaron Wade)

Red Squirrel on a cold winter day (Aaron Wade)

Red squirrels are feisty little mammals that are common in any neighborhood with trees. They chatter and “boss” larger gray squirrels around and will also make pests of themselves by burrowing into the attics of homes. Their “chick-a-ree” call is common in neighborhoods. Red Squirrels are active only during the day and eat many types of seeds and cones: including pine cones, acorns, and sunflower seeds. They are excellent gymnasts and can race around trees as if they are on the ground. Red Squirrels make leaf nests (called a dray), that are usually found on the outer branches of a tree. However, their favorite type of home is a tree hole, 2-3 inches in diameter. Tree holes are usually made by woodpeckers, but are also created when a branch breaks off. Red Squirrels are active during the winter, except on very cold days when they hide out in their nests.

Flying Squirrel

A flying Squirrel gliding

A flying Squirrel gliding

Flying squirrels can not actually fly, but glide downward from one tree to the next. They stretch the loose folds of skin between their arms to glide. A flying squirrel usually glides 20 to 30 feet, but is capable of going as far as 150 feet. They are about the size of a chipmunk and weigh 2-3 ounces. Since they are nocturnal, they have very large eyes to help them see in the limited light.

Flying squirrels eat a variety of fruit, nuts, insects and small birds. They are common and frequently visit feeders. But since they are nocturnal, they are not usually seen by people.

Flying squirrels live in tree hollows that are usually made by woodpeckers. Their food is stored in their nests, and not on the ground like other squirrels. Also, they are the only nocturnal species of squirrel in Minnesota.

In the winter, flying squirrels do not hibernate, and will nest together in groups to stay warm.
Predators on flying squirrels include owls, fox, weasel, and small hawks.

Cottontail Rabbit

Cottontail Rabbit

Cottontail Rabbit

Cottontail rabbits are found throughout Southern Minnesota in brushy areas. During the summer they feed on grasses and clovers. But in winter they eat twigs, bark and like to hide in brush piles.

Cottontails are capable of producing many young each year. A female will give birth to six young in a shallow hole that is lined with fur. The young are born hairless and blind, but grow quickly. Within three weeks she may have another litter while the young from the first litter are weaned and must fend for themselves after only two weeks. A female will raise three to four litters during the spring and summer season.

Cottontails are active all year. They do not hibernate in winter, but may hide in a groundhog hole during very cold weather. They are most active in the at night between dusk and dawn.

Young cottontail hiding

A camouflaged young cottontail

Many types of animals eat cottontails including red fox, hawks, owls, weasels, and snakes. But they are able to avoid predators by running almost 20 miles/hour and dodging and turning quickly.

The grasses and twigs that cottontails eat are very hard to digest. To improve digestion, rabbits eat their droppings and re-digesting their food a second time.


Mink feeding on  dead carp in early spring

Mink feeding on dead carp in early spring

Mink are in the weasel family and have a long-thin body and tail (up to 28 inches). They are all dark with a white splotch under their chin. Mink are usually found near water, capable of swimming well, and their feet are partially webbed. In the spring, mink dens can be pretty “stinky”. Dens are usually “scent marked (urinate at the entrance) to let other mink know they have set up a breeding territory. Dens are along the edge of ponds or streams, usually under stumps or tree roots. Mink may use the bank den of a muskrat instead of digging their own den. A litter of 3-6 kits (young) are born in April or May in a den layered with soft feathers, fur and plant material. The kits are born hairless at birth, but quickly grow hair and open their eyes in less than a month. Weasel kits remain with their mother till fall.



Mink do not hibernate in the winter, and have been know to store food in their den. They are most active at night, but can be seen during the day too. Mink eat a variety of foods including: muskrat, fish, crayfish, snakes, frogs, and birds.

Mink have few enemies. Great horned owl, coyotes, and foxes have been known to kill small numbers of mink. Young mink are most susceptible to being killed after leaving the den in Fall.

Striped Skunk

Striped Skunk Dominique Braud

Striped Skunk
Dominique Braud

Skunks are another member of the weasel family and best known for the smelly scent they are capable of releasing. The scent glands are located near the anus and can be squeezed such that the fluid can shoot as far as 16 feet.

Skunks are nocturnal and are usually found in open grassy areas. Its sense of hearing and sight is poor. The sense of smell is moderate, and its sense of touch is excellent.

Skunks mate in early March and usually have four to six young in a litter. The young are born in May and stay with the female till August.

Striped skunks are omnivores, meaning they eat plant and animal foods including: insects, wild fruits, mice, worms, birds, nuts and garbage. In 1976, there was a drought (no rain) and skunks could not find enough to eat. The skunks living near Bemidji, MN invaded the town and ate garbage, spent the winter in the town, and raised their young there the following summer.

Their biggest enemies are great horned and barred owls. Owls have a poor sense of smell and can handle the putrid smell of skunk spray.

Skunks eat a lot of rodents that would usually cause damage to crops. However, skunks are one of the few mammals that carry rabies. The incidence of skunks with rabies in farming areas is fairly high.

Short Tailed Weasel

Short-tailed Weasel www.featheredphotography.com

Short-tailed Weasel

The short tailed weasel is active day or night. They are common, but seldom seen. Short tailed weasels are small (less than 13 inches) and thin bodied, allowing them to get into tight places. They are very skillful hunters, moving with lightning speed on the ground. A weasel will pounce on its prey with all four feet, biting through the neck and killing it. Its main diet is mice, but it also eats baby rabbits, frogs, snakes and grasshoppers. It is ferocious and a fearless hunter, capable of capturing prey larger than itself (young cottontail rabbits).

Weasels live in woodlands and brushy areas. Dens may be found around tree stumps, logs, or they may kill a chipmunk and then take over its den. A weasel may keep several dens in its territory, using them when they are needed. A male weasel has a territory that has several females living in it. The young are born in mid April and are hairless. But by late June they begin to kill their own prey.

Weasels are active all winter and do not hibernate. In the winter their coat changes from brown to white, while the tip of the tail remains black. The white coat camouflages the animal in winter, while the black tip of the tail wiggles back and forth and may fool a hungry owl into diving on to the tail and not the weasel’s body. The short tailed weasel or ermine, as it is called, is valuable to trappers for its white winter coat. Although fur coats have been not been in style for over a decade which has reduced hunting pressure on weasels.

River Otter

River Otter at Sunrise

River Otter at Sunrise

River otters are the largest member of the weasel family. They may be over five feet long and weigh up to 30 pounds.

Otters are found around rivers and lakes. They are expert swimmers and are very agile and fast. Their hind legs are webbed.

The den of an otter is well hidden, and may be located in a bank along a stream or lake, always with the main entrance under water and usually below the ice line. Otters may slide down steep hills and into a lake.

River Otter at Sunrise

River Otter female with pup.

River otters eat all types of animals that live in the water including: fish, crayfish, frogs, ducks, water beetles and larvae. They are active all winter long and are capable of hunting for food beneath the ice for over two minutes.

They have few enemies other than humans. Otters may get killed by cars as they move from one lake to another. Water pollution is another factor that has reduced otter populations. If an otters coat is fouled by motor boat oil, they may not be able to stay warm in the winter. Currently otters have been seen in the Minnesota River and Mississippi rivers. They are more common in northern Minnesota.

Marsupial Family


Opossum Mike Farrell

Mike Farrell

Twenty years ago the opossum was rarely seen, but it has recently expanded its range into Minnesota. They are found in the Twin Cities, but not in northern Minnesota. One limiting factor is they have a long bare tail and their ears are susceptible to frostbite on cold winter days.

The opossum is the size of a house cat. It has a prehensile tail which wraps around tree limbs as it climbs a tree.

Opossums are slow moving and usually hide in hollow logs during the day, and at night forage for food. They feed on frogs, snakes, rodents, fruit, insects and other foods.

An opossum is more closely related to kangaroos than any animal in Minnesota. The female has a pouch to carry its young. The young are born blind and hairless, and remain in the pouch for over 2 months. As they grow to mouse size, they will climb in and out of the pouch and up on to its mother back.

Predators on opossums include cars, dogs, fox, hawks and owls. Opossums try to survive a predator attack by “playing dead” and secreting a stinky smelling scent.

White-Tailed Deer

Deer  (Paul Gagner)

Deer (Paul Gagner)

The white-tail deer is the largest mammal that Minnesotans can easily see in their neighborhoods. They get their name from the large white-tail that they raise to warn other members of the herd, when danger is near.

The fawns are born in late May and early June. They weigh only 6-8 pounds at birth and grow to sixty pounds in six months.

Newborn fawns spend most of their day bedded on the forest floor. They are left alone by the doe, who needs to eat. Their best defense from predators is the spots on their backs that help camouflage them.

Deer are over-populated in Minnesota. In many cities, deer are being trapped and shot to reduce their numbers. After the fawns are born, there are roughly a million deer in Minnesota. The hunting season is important to keep the deer population from getting too high. Each year hunters kill roughly 200,000 deer.


Bull moose photo by Nancy Saslow

Bull moose
photo by Nancy Saslow


The moose is the size of a horse and is the largest member in the deer family, weighing up to 1200 pounds.

Moose feed on a variety of plants: willow, dogwood, birch and fir trees. In the summer, moose feed on water plants. They swim well and eat plants that are both above and below the water. Many of the plants that moose like are also eaten by deer. But the moose’s large size allows it to walk through deep snow easier. This makes it easier for moose to survive in snowy areas.

The antlers are dropped in January or February and can be six feet across. The antlers grow throughout the spring, then in the fall the furry “velvet” is shed from the antlers. The bulls use their antlers for fighting during the mating season.

Moose are found primarily in northeastern Minnesota. The population has been estimated by DNR biologists to be 4000 animals and the population has decreased in recent years. One cause of the decline is that researchers have found a parasite which attacks the moose’s liver. Also, higher summer temperatures in Northern Minnesota has caused stress in the population. This has a negative effect on moose during the cold winter months. As a result, there are fewer moose being born in the Minnesota northwoods.


Mike Farrell, of Susan Lindgren School St Louis Park, took the photo of the opossum.
Paul Gagner contributed the deer photo.
Dominique Braud, wildlife photographer, contributed the skunk photo.
Steve Gordon took the fox pup photo.
www.featheredphotography.com –  short-tailed weasel photo
true-wildlife.blogspot.com – flying Squirrel photo
www.revelstokebearaware.org – Black Bear photo

The following resources were also used:
Gilbert, Jim. Through Minnesota’s Seasons with Jim Gilbert. Chanhassen, MN. Minnesota Landscape Arboretum, 1987.
Jackson, Hartley, Mammals of Wisconsin. Madison, Wisconsin. University of Wisconsin Press, 1961.


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