Category Archives: Mammals

Meadow vole – Microtus pennsylvanicus

General: Meadow voles (Microtus pennsylvanicus), sometimes called the field mouse or meadow mouse, are a small, common rodent that inhabits much of North America.  They are prolific breeders whose populations tend to irrupt every few years.  They are of the order Rodentia and family Cricetidae.  Their presence can be determined by their unique tendency to construct nests that are surrounded by systems of runways. 

Description: Meadow voles reach a mature length of 3.5” to 5”.  Their tails, which are scaly and have little hair, may reach 1.4” to 2.6” in length, nearly 40% of their complete body length.  Their mature weight is between 1oz. to 2ozs.  Meadow voles can be identified by their compact bodies, large, slightly angular heads and small noses.  Their ears, relative to other rodents, are small and lay fairly flat against the sides of the head. 

Meadow voles have coarse dark brown or reddish brown hair mottled with black and lighter or white undersides.  In the winter, their hair tends to be duller.  There are no noticeable physical variations between males and females.

Meadow voles tend to be active throughout the day (usually above ground,) but become more diurnal during the cold months and nocturnal during warmer months.  Because meadow voles do not hibernate, they spend the majority of their time throughout the year in search of food.  They are skilled diggers and swimmers1.  

Meadow voles generally build 6” to 8” round nests2 above ground but sometimes construct them within shallow burrows, using dry vegetation.  During cold months, mixed-age and mixed-gender groups of non-reproducing voles may share a nest to conserve body temperature.  The nest is the epicenter of a system of runways, used as sheltered passageways and typically littered with vegetation cuttings and droppings3. 

Breeding females tend to be territorial of their home ranges (which are distinct from other females’ ranges,) while males are mobile and have ranges that are generally three times the size of females’ ranges.  If more than one female occupies a range, the females tend to be a mother-daughter pair (and in this case, the mother typically prevents the daughter from breeding.) 

Meadow voles may become aggressive if they are cornered or caught, stomping their feet and attacking to avoid danger.  They use their runways (that are often covered in vegetation) for protection from predators, including birds of prey, snakes, bullfrogs, snapping turtles, foxes, weasels, shrews, raccoons, and cats4.  The meadow vole is a major component of the diets of many of its predators.

Meadow voles have highly developed senses of hearing and smell, and communicate using chemical markers (droppings and urine are used to determine identity, sexual readiness, and proximity,) physical gestures, and vocalizations (including growls, squeals, and chatters.)  The young emit ultrasonic signals.  The majority of vocalizations are created in response to threats5.

Meadow voles are commonly preyed upon and often do not live more than one year in the wild, although they have been known to live as long as 2.7 years6.

Habitat: Meadow voles are predominantly found in low-lying fields, meadows, grassy marshes, grasslands, orchards, open woodlands (deciduous and mixed forests,) and occasionally in low wetlands, flooded marshes, and along river or lake shores. 

Location: Meadow voles thrive throughout most of North America, from central Alaska, south to New Mexico and Georgia, as far west as the Rockies and east to the Atlantic coast7.

Diet: Meadow voles consume nearly 60% of their own body weight daily, feeding on a varied diet that consists mainly of grass, succulent vegetation, herbs and sedges found within their geographic ranges during warm months.  During the fall, their diets consist mainly of seeds and grains and in the winter, meadow voles subsist on the roots and inner bark of trees and shrubs, which they harvest through girdling.  They may also eat fruit, tubers, bulbs, flowers, leaves, insects, and at times, flesh. 

Meadow voles do not generally store food, except for some small caches in preparation for the winter8.  Because of their lack of food hoarding, meadow voles spend the majority of their time feeding.

Reproduction: Meadow voles are prolific breeders capable of having more than twelve litters in one year, determined by climate, food supplies, population densities of meadow voles and predators, and individual behavior.  Breeding may occur during any month but is more frequent during warm months when food is readily available.  Unless their populations are controlled or the carrying capacities of their environments are met, their populations may irrupt every three to five years9.  Typical population densities average forty to eighty voles per acre10.

Females in estrous fiercely defend their territories and are sought out by males, who may aggressively compete with each other or establish temporary hierarchies to determine mating rights.  After mating, females drive males away. 

After a twenty-one day gestation period, the female gives birth to a litter of one to eleven pink, blind, hairless young that weigh just over 2 grams each.  After eight days, their eyes open, within twelve to fourteen days, the young are weaned and by three weeks old the young are independent.  Females reach sexually maturity within one month (at which point they are capable of having a litter nearly every three weeks for the rest of their lives,) and males reach sexual maturity within thirty-five days11.

Notes of Interest: Meadow voles are considered to be pests because of the destruction they cause in orchards and forestry initiatives12.














American mink – Neovison vison

General: The American mink (Neovison vison) is a medium-sized, semi-aquatic mammal that is a member of the mustelid family.  The American mink is native to the United States and Canada and has been introduced to several non-native habitats as a fur-bearer and game animal.  The American mink is best known for its glossy, thick, dark coat and long, lean body.  Humans pose the biggest threat to this species.           

Description: American mink are recognizable because of their long, slender bodies that are covered in thick, dark fur.  Full-grown, males are 22.5” to 27.5” in length, while females are smaller, reaching a mature length of 18” to 22.5”.  Their thick tail may make-up half their body length.  Similarly, mature males tend to be about 20% heavier than females, weighing 2 to 3.5lbs. while mature females weigh 1.5 to 2.5lbs.  Their length is emphasized by short sturdy legs and a long neck.  American mink have flat faces and conical heads with petite eyes and ears.  Because mink are semi-aquatic, their toes are webbed1.

American mink may be best known for their luxurious dark brown to black fur (made-up of a dark brown undercoat and long, oily guard hairs that waterproof the coat2.)  Their thick, shiny, soft coat is accented by patches of white fur on the chin, neck and chest. 

Mink don’t hibernate and are most active at dawn and dusk.  A semi-aquatic mammal, mink are skilled swimmers and tend to spend much of their time in and about the water searching for food.  They are capable of swimming up to 100’ underwater and diving up to 15’ below the surface.  Because of their dependency on the water for hunting, mink locate their subterranean burrows along the banks of bodies of water, or take residence in the abandoned burrows of other animals.  These dens are dug out then lined with dried vegetation and fur.  American mink tend to use each den for only a limited time before building a new den.

Because of their aggressive and defensive nature, American mink tend to be solitary animals.  Males are especially territorial and mark their home ranges with secretions from their anal glands (similar to skunks.)  Mink also use chemical secretions to communicate their sexual status.  Mink are known to be aggressive when faced with a threat from a predator.  However, mink are skilled at avoiding confrontations because of their agility, sly nature and dark coloration that blends well with their surroundings.

In addition to chemical cues, American mink communicate using visual and auditory cues, since they have highly developed senses of hearing, vision and smell3.  Mink are capable of making a limited range of sounds, including a pur when content4.

Mink may live up to 10 years old.

Habitat: American mink exist in a variety of habitats, including grasslands, forests, and marshes, but tend to prefer forested areas that offer access to water (near ponds, streams, or lakes,) and areas with brush or rock cover for protection5.

Location: American mink populations can be found across the United States and Canada (except for the southwestern United States, Hawaii, coastal areas of Canada along the Arctic and some Canadian islands.)  Populations have been introduced to Newfoundland and the British Isles (where mink were accidentally released or escaped from fur farms6.)

Diet: The American mink is carnivorous and consumes a diverse diet that changes throughout the year.  During warm months, their diets include aquatic animals (frogs, crayfish, and fish,) and small mammals (such as rabbits, muskrats, mice, chipmunks, and shrews.)  During cold, winter months their diets consist mainly of small mammals.

American mink have been known to store extra food within their dens7.

Reproduction: American mink are promiscuous and mate annually during the winter.  Fertile females may mate with multiple males.  After a gestational period of 40 to 75 days, the female gives birth in the late spring to a litter of one to eight young, within a fur-lined nest.  At birth, the young weigh 8 to 10g, are blind and wrinkled, and have a coat of fine white hair all over their bodies.  Their eyes open around 25 days old and by six weeks they are fully weaned (although the young may remain with their mother into their first fall.)  By 6 to 10 months old, the young become independent and leave their mother to establish their territories.  By 10 months old, American mink reach sexual maturity8.

Notes of Interest: Humans pose the greatest threat to the American mink (because of the high value of their fur.)  Mink are also hunted by coyotes, bobcats, birds of prey and other carnivores.  Common to other mustelids, minks are fearless and defend themselves aggressively when faced with a threat, although their coloration and allusive nature help protect them before these threats present themselves.

Limited trapping seasons for the American mink exist in forty-seven states and in all of the Canadian provinces9.

Due to the high demand for their fur, mink are bred on fur farms.  Through selective breeding, a broad spectrum of hide colors has been established, ranging from black to white.  These colors have become established in some wild populations (including some in South America, Europe and Newfoundland,) because of mink that have escaped from farms or been released from farms (by animal activist groups.)

Tens of thousands of mink were intentionally released into the Soviet Union over the coarse of several decades to provide a new game animal for hunters.  However, this introduction caused a severe shift in local eco-systems and had negative impacts10.












Fox Squirrel – Sciurus niger

General: The fox squirrel is the largest of the American tree squirrels. They are “tree squirrels” which means they are associated with other climbing squirrels that spend time and nest in trees. Fox squirrels usually have more than one nest. Their nests can be leaf nests much like those of gray squirrels or they may use hollowed out sections of tree branches or trunks. I have read that they have introduced into certain areas of the western continental USA – if so I would consider them to be an invasive species.

Description: There are three geographical color phases of fox squirrels: in most areas the animals are brown-grey to brown-yellow with the belly pale yellow to orange in color (as the picture of the squirrel standing on its hind legs indicates). The Tufts behind the ears and the tips of its tail are yellowish-brown. The tail itself is a reddish-orange with a mixture of dark gray or black hairs throughout. A second coloration phase in eastern regions such as the Appalachians are more strikingly-patterned dark brown and black with white bands on the face and tail. In the south they can be found in isolated communities with uniform black coats.

These are good sized tree squirrels with body length measuring 18” – 24” and their tail measuring between 8” – 13”, almost ½ of the total length. Average weight for these tree squirrels is between 17oz. – 38 oz. (1 lb. – 2 ¼ lbs.)

Habitat: The primary habitat of the fox squirrel is in woodlot country of agricultural lands, in suburban communities and open forest with clear understories they are not found in stands with dense undergrowth.. As with other squirrels, fox squirrels will be found where timber provides food and broken stands of middle aged and mature trees for dens.

Location: The fox squirrel’s natural range extends throughout the eastern United States, excluding New England, north into the southern prairie provinces of Canada, and west to the Dakotas, Colorado, and Texas.

Diet: Just like other squirrels, fox squirrels eat various types of nuts – hickory, oak, beech, pine, etc. They also eat fruits such as blackberry, dogwood, cherry and grape. They will eat farm produce such as corn, squash (the picture of the fox squirrel standing was taken as it was eating a pumpkin). In spring they will eat buds of maple (as well as the seeds) elm and willow. Fox squirrels are also known to eat insects, young birds as well as the eggs. They will also eat fungi, mushrooms etc. Audubon mentions that fox squirrels actually carry out a beneficial role in forest life by spreading certain fungi spores – for more information go to Audubon.

Reproduction: Female eastern fox squirrels come into estrus in mid-December or early January then again in June. Male fox squirrels initiate the chase of the female that leads to mating. Fox squirrels are polygamous, meaning the male will mate with more than one female and the female may mate with more than one male. Fox squirrels can have 2 litters per year. One litter occurs in late winter/early spring, the second litter in late summer.

Gestation period is approximately 45 days after which 2 – 4 young are born. The young are born with their eyes closed and will not open them for approximately 1 month. They will depend on the female for about seven weeks and become independent after three months. (Audubon)

Notes of Interest:

When nuts are available, squirrels will harvest as many as they can typically burying them in the ground. They will return when hungry and dig them up.

Like gray squirrels, fox squirrels use two types of nests: leaf and den. Leaf nests are constructed from leaves and twigs and are located in the crotches of tree branches. Dens are formed in hollow tree trunks or branches. Nests are used for shelter and rearing young.

Fox squirrels are a prey species for all predators and especially for those that hunt in or on trees.

According to Minnesota DNR, “hunters harvest about 160,000 of these rodents”.
In captivity, eastern fox squirrels have been known to live 18 years.

Learn about squirrel hunting by clicking here.

Bighorn Sheep – Ovis Canadensis

Bighorn sheep get their name from the large, curved horns on the males, or rams. They are legendary for their ability to climb high, steep, rocky mountain areas.

Bighorn Sheep – Ovis canadensis


Bighorn sheep get their name for the large, curved horns on the rams. The ewes have horns but they are shorter with less curvature. The males are called rams while the females are called ewes.

Bighorn sheep are known for the male head-to-head combat during mating season. They charge each other at speeds of more than 20 mph. This is done to establish dominance hierarchy and access to ewes for mating.

Bighorn sheep live in herds or bands of about 5 to 15 ewes, lambs, yearlings, and two-year olds. Groups of males are much smaller, usually numbering two to five. In the winter, the ewe herds join to create bands of as many as 100 animals.


As their name implies, male bighorn sheep have large curved horns that can weigh up to 30 lbs.
Bighorn sheep range in color from light brown to grayish or dark, chocolate brown, with a white rump and lining on the backs of all four legs. Males typically weigh 127 – 316 lbs. with an occasional ram from the Rocky Mountains reaching 500 lbs. Females typically weigh between 75 – 188 lbs. In height, the males are approximately 36” – 41” tall at the shoulder and 69” – 79” long. Females are approximately 30” – 36” tall and 54” – 67” long.

Habitat:Females have their babies on a cliff that's hard to access. They have one baby. Lambs are woolly and white and have little horns. They can walk and climb by the first day.

Bighorn sheep generally inhabit alpine meadows, grassy mountain slopes, and foothill country near rugged, rocky cliffs and bluffs. Since bighorn sheep cannot move though deep snow, they prefer drier slopes, where the annual snowfall is less than about 60 inches a year. A bighorn’s winter range usually lies at 2,500–5,000 feet in elevation, while its summer range is tends to be at 6,000–8,500 feet.


Bighorn sheep were once widespread throughout western North America. By the 1920’s, bighorn sheep were eliminated from Washington, Oregon, Texas, North Dakota, South Dakota, Nebraska, and part of Mexico. Today, populations have been re-established through transplanting sheep from healthy populations into vacant places.


Bighorn sheep are herbivores and as such graze on grasses and browse shrubs, particularly in fall and winter, and seek minerals at natural salt licks. During the summer, they subsist on grasses or sedges. During the winter they eat more woody plants, such as willow, sage and rabbit brush. Desert bighorn sheep eat brushy plants such as desert holly and desert cactus.

Interesting facts:

Recent genetic testing indicates three distinct subspecies:
1.    Rocky Mountain bighorn sheep (O. c. canadensis), occupying the U.S. and Canadian Rocky Mountains and the northwestern U.S.
2.    Sierra Nevada bighorn sheep (O. c. sierrae), formerly California bighorn sheep, a genetically distinct subspecies that only occurs in the Sierra Nevada
3.    Desert bighorn sheep (Ovis canadensis nelsoni), occurring throughout the southwestern desert regions of U.S. and Mexico.

By 1900, the population had crashed to several thousand, due to diseases introduced through European livestock and overhunting. Conservation efforts (in part by the Boy Scouts) have restored the population.

Bighorn sheep are highly susceptible to certain diseases carried by domestic sheep. The National Park Service in Yellowstone,, references an outbreak of pinkeye, a disease associated with domestic sheep, that caused a sharp decline in the Park’s bighorn sheep population in the early 1980’s.

Predation primarily occurs with lambs, which are hunted by coyotes, bobcats, lynxes and golden eagles. Bighorn sheep of all ages are threatened by bears, wolves and especially cougars

The lifespan of rams is typically 9–12 years, and 10–14 years for ewes.

The Rocky Mountain bighorn sheep is the provincial mammal of Alberta and the state animal of Colorado and as such is incorporated into the symbol for the Colorado Division of Parks and Wildlife.

They are legendary for their ability to climb high, steep, rocky mountain areas.


Back to Mammals

Coyote – Canis Latrans

General: The scientific name of the coyote is Canis latrans which means “barking dog”. If you have ever been out in the woods while coyotes were present and heard their high-pitched howls, yips, yelps, and barks, you will understand the nature of their name.

The coyote is one of the animals that were been able to enlarge their range and thrive due to human population growth. It originally ranged primarily in the western half of North America and they were preyed on by wolves and mountain lions. In fact wolves have kept coyote populations in check. Many studies conducted by researchers have concluded that the introduction of wolves in Yellowstone Park reduced the coyote population. With the absence of apex predators coyotes have been able to expand their range throughout the entire contiguous 48 states and Canada.

Without natural control, wolves etc., coyote populations and densities rarely are reduced or even controllable by humans through hunting and trapping. In fact, studies have shown an increase in reproductive rates in areas where coyotes were intensively removed – females may even come into heat twice a year in such conditions. And, unlike wolves, the really is no alpha male and female coyote, most female coyotes will mate. It has been estimated that over 65% of a coyote population (adults and young) would have to be removed annually to overcome their reproductive potential and lead to an overall population decline.
Coyotes become sexually mature usually the first breeding season; however, the proportion of juvenile animals (less than 1 year old) participating in breeding depends on environmental conditions, food availability, and population density. In general, 60% – 80% of adults and 20% – 25% of juvenile females breed and bear young each year (Parker 1995). Non-breeding females tend to be individuals that do not hold a territory. (3)

Common names of coyote groups are a band, a pack, or a rout. The group is many times a ‘family unit’. Each family unit is made up of the adult pair and their pups from the current year. A family unit will defend a territory of 6 to 15 square miles against other coyotes.

A study by the Genome Research Project has identified that as coyotes have moved into new areas they have acquired DNA of both domestic dogs and wolves. The chart below summarizes these findings.

Coyote Dog Wolf Total
Western Coyote





Northeastern Coyote





Midwestern Coyote





Southeastern Coyote






1. Northeastern population location as name indicates are the New England states including eastern New York

Eastern coyote genetics and skull morphology shows that remnant wolf populations in Canada hybridized with coyotes expanding north of the Great Lakes, thereby contributing to the evolution of coyotes from mousers of western grasslands to deer hunters of eastern forests. The resulting coy-wolf hybrids are larger, with wider skulls that are better adapted for hunting deer.  (1)

A study showed that of 100 coyotes collected in Maine, 22 had half or more wolf DNA and one was 89% wolf. The large eastern coyotes in Canada are proposed to be actually hybrids of the smaller western coyotes and wolves that met and mated decades ago, as the coyotes moved toward New England from their earlier western ranges. (2)

2. Midwestern population Ohio south into Mid-Atlantic out to the Mississippi boundary

3. Southern population below Mid-Atlantic to Florida out to the Mississippi boundary

4. Western population west of Mississippi River

As the chart show, coyotes and dogs can interbreed. The offspring are referred to as ‘coydog’. The problem has been the offspring have a reproductive cycle of dogs, not coyotes, and will give birth at times of the year (January) when the pups cannot possibly survive in northern climate. With that said, domestic dog DNA is present in much of the coyote population.

Interesting Facts:

During pursuit, a coyote may reach speeds up to 43 mph and can jump a distance of over 13 ft

Coyotes have been known to live a maximum of 10 years in the wild and 18 years in captivity

Litter size ranges from one to 19 pups; the average is six.

Identification:   Coyotes typically grow to 40” – 50” in length – including the tail which measures about 10” – 16” and stand about 20” – 26” at the shoulder. Depending on region, coyotes can weigh from 15 lbs. – 50 + lbs.

Fur Color is variable and can be blonde or reddish blonde to dark tan washed with black. Coyote legs, ears and cheeks usually reddish in color. Black patches on base and tip of tail help distinguish from dogs

Habitat: Territory:  found throughout North and Central America, ranging from Panama in the south, north through Mexico, the United States and Canada. It occurs as far north as Alaska and all but the northernmost portions of Canada.

Diet:  Coyotes are opportunistic omnivores which is part of their success resulting in increased range and population. They will eat anything. In the wild they prey on small indigenous animals depending on the season. They primarily eat small animals such as mice, squirrels, prairie dogs, rabbits, ground squirrels, birds, snakes, lizards, insects, fish, deer, domestic livestock, trash and the family pet. They will consume large amounts of carrion. Fruits and vegetables are a significant part of the coyote’s diet.

Acting as a pack coyotes have taken down deer, large domestic dogs and should be considered dangerous to humans.

Attacks on humans: Coyote attacks on humans are uncommon but they do occur. Data from USDA Wildlife Services, the California Department of Fish & Game, and other sources show that while 41 attacks occurred during the period of 1988–1997 and 48 attacks were verified from 1998 through 2003. There are only two recorded fatalities in North America from coyote attacks.



2 IF&W in collaboration with Paul Wilson, Trent University


Eastern Cottontail Rabbit

General: The eastern cottontail rabbit, as with all rabbits, are prolific animals. A female may give birth and within hours after giving birth, be bred again. Three weeks later she will have another litter. The young of the first litter fend for themselves when the second litter arrives.

Eastern cottontail rabbit feces is typically round and approximately 1/4″ in diameter. There is typically a small grouping of pellets together. The picture below is of eastern cottontail feces.

Almost all predators including rattlesnakes, hawks, mink, foxes, bobcats, fishers, weasels, coyotes, dogs, cats, skunks, raccoons, and wolves eat cottontails.

The cottontail breeding season typically begins in late February and lasts through September. Gestation lasts 27-32 days. The female will breed and multiple litters will be born each year – a female will have anywhere from 1 – 6 litters each season!!

When pregnant, the female (doe) will dig a nest cavity. The nest measures 5” – 7” wide and approximately 7” deep (see picture). She will line the nest with grass and leaves and then with her fur. Typically, after the nest is complete, the opening is covered up.

At birth, kits are hairless, sightless, and virtually helpless. There are typically 3-6 young in each litter. They weigh about an ounce. Kits leave the nest after three weeks.

The pictures of the cottontail in the flowers shows how the nest is built, what the excavation looks like and finally when complete, how the doe camouflages the opening. It only took the rabbit approximately 10 minutes from start to finish. Several weeks later my wife watched the doe breast feeding the kits. Two weeks later the nest was abandoned. Reproductive maturity occurs at about 2 to 3 months of age.

A disease that is deadly to rabbits is tularemia. Tularemia is caused by a bacterium, Pasteurella tularensis, which is transmitted to the rabbit by ticks or fleas. A number of wildlife species and humans can contract the disease, but it usually occurs in rabbits and rodents. The disease is always fatal to the rabbit, with most succumbing to the illness within 10 days following onset. As mentioned, humans can contract the disease. However, it responds quickly to antibiotics and is not considered a serious health threat if treated promptly. The following precautions will greatly reduce your risk of exposure:








•Do not harvest rabbits that appear sluggish or do not run.
•Wear rubber gloves when dressing rabbits.
•After removing the gloves, wash your hands with antibacterial soap.
•Cook rabbit meat thoroughly. Do not eat rare or undercooked rabbit meat.

Identification: The eastern cottontail is chunky red-brown or gray-brown in appearance with large hind feet, long ears and a short fluffy white tail. Its underside fur is white. There is a rusty patch on the tail. Its appearance differs from that of a hare in that it has a brownish-gray coloring around the head and neck. The body is lighter color with a white underside on the tail.

The average adult weighs about 2 – 4 lbs with the female tending to be heavier. They are between 12” – 16”.

Habitat: Optimal eastern cottontail habitat includes open grassy areas, clearings, and old fields supporting abundant green grasses and herbs, with shrubs in the area or edges for cover.

Eastern cottontails can be found on farms, fields, pastures, open woods, thickets, fencerows, forest edges, and suburban areas. They are also found in swamps and marshes and usually avoid dense woods. Trick here is to look for food and cover.

They are seldom found in deep woods.

Territory:  The eastern cottontail has a wide distribution and is found throughout most of the eastern United States. They range from eastern and south-central United States, southern Canada, eastern Mexico, Central America and northernmost South America. Originally, it was not found in New England, but it has been introduced there and now competes for habitat there with the native New England Cottontail.

Diet: Cottontails eat green plants, twigs, tree bark, fruits, buds, flowers and seeds. I have watched eastern cottontail rabbits eat fallen bird seed during winter.  Eastern cottontails produce two types of fecal pellets one of which is consumed. The digestion of fecal pellets increases the nutritional value of dietary items. They are a pain in the ass in the garden. They have eaten my bean plants, carrot tops, beet greens, cabbages, etc. During winter they have gone after my blue berry plants.