Squirrel on path


Mammals are warm-blooded animals that bear their young alive and nurse them for a period of time. Parental care is much more extensive than it is among other animals with few exceptions. Mammal behavior is more complex and in most cases less purely reflexive, or instinctual than is true with other types of animals. Humans are mammals, of course.

Mammals probably evolved as small, insect eaters about the same time as did the dinosaurs. The dinosaurs became dominent, though, and mammals occupied only small niches on the fringes of the ecosystem. Apparently some differentiation into groups occurred even during the time of the dinosaurs. Genetic studies have shown divergence dating back to before the end of the Cretaceous, the time at which the dinosaurs all died off along with much of the other fauna and flora of the planet. Current evidence indicates a meteor strike and the aftermath (obscuring dust clouds and the resulting climatic change, etc.) caused the extinction and gave mammals a chance to develop into the wide variety we see today – including those writing and reading these words.

A large number of mammals are found in our part of the world, but most of them are obscure. With a few exceptions, they are hard to find and hard to identify, even visually, in many cases. The sounds they make are often similar or rarely heard. Nevertheless, it is worth listing them with important points about their habits.


Bats are the only mammals that truly fly. There are a hundreds of species world-wide. Of these, six have been seen in our area. Some bats hibernate. Some migrate. Some do both. Some roost during the day hanging from tree branches. Some hide in tree cavities, caves, or boxes put out by considerate humans, many of whom appreciate the vast quantities of biting insects bats consume in evening and night. The voices of bats are various squeeks, hisses, and grunts, rarely heard. Don’t worry about identifying bats; that is a job for experts. For the rest of us, it can drive you, well, er, bats. Just take an occasional moment during the evening hours to offer thanks to the little critters for all the bugs they eat. But don’t try to pet them. Some bats carry rabies, and many of them bite worse than the insects. Bats catch the insects by echo-location, a technique that may have led to the development of radar. The sounds they make are supersonic to us, so you won’t hear them.
Slowed down through an alalyzer (DVG), this is what they sound like.

The Bats

  1. Little brown bat (Myotis lucifugus) weighs 1/4 to 1/3 ounce and is brown. Roosts in caves, mine tunnels, hollow trees, or buildings. Migrates and hibernates.
  2. Keen myotis (Myotis keeni); same size and roosting habits of the above. Hibernates. Dark brown.
  3. Silver-haired bat (Lasionycteris noctivagans) weighs 1/3 to 2/5 ounce. Blackish-brown with back hairs tipped with white. Roosts in trees. Migrates.
  4. Big brown bat (Eptesicus fuscus) weighs 2/5 to 3/5 ounce. Dark brown. Caves, tunnels, hollow trees, buildings, woods. Some migrate, some hibernate.
  5. Red bat (Lasiurus borealis) weighs 1/3 to 1/2 ounce. Brick to rusty red. Roosts in trees. Migrates.
  6. Hoary bat (Lasiurus cinereus) weighs about an ounce. Shades of brown with white-tipped hairs. Roosts in trees. Migrates.

Shrews and Moles

Shrews are small, very small, animals. They are quite common despite the fact that most people know nothing of them. Many species are smaller than a mouse. They eat insects and generally have musk glands that produce a bad scent. Cats catch them because they dart around like mice, but find they can’t eat them once they have killed them. They eat insects. Moles tunnel under the ground and eat the grubs and insects they find there.


  1. Masked shrew (Sorex cinereus) is 2 to 2 one half inches long, tail included. Brownish-gray. Lives in all manner of wet country. Active day and night. Eats more than its own weight each day. Heartbeats more than 1200 per min.
  2. Smoky shrew (Sorex fumeus). 2 and one half to 3 inches. Uniform dull brown except tail and pale feet. Found in birch and hemlock forests with deep leaf mold.
  3. Longtail shrew (Sorex dispar). Tiny. 2 and three-quarters inches, most of which is tail. Gray. Cool moist habitats in deciduous or mixed woods.
  4. Northern water shrew (Sorex palustris). 3 and one third inch body, tail almost as long. Blackish-gray. Cold streams, bogs. Swims readily.
  5. Pygmy shrew (Microsorex hoyi). Length 2 to 2 and one half inches, at least half tail. Weighs one ninth to one seventh ounce. That’s what a dime weighs. May be smallest living mammal. Wooded areas.
  6. Shorttail shrew (Blarina brevicauda). Head and body 3 to 4 inches. Tail shorter. Lead color. Active day and night all year. Voracious. May even eat young mice.


  1. Starnose mole (Condylura cristata). Head and body 4 and one half to 5 inches, tail almost as long. Dark brown or black. Short fleshy projections or tenticles surrounding nose giving appearance of star. Active day and night. Low, wet ground near streams or lakes.
  2. Hairytail mole (Parascalops breweri). 4 and one half to 5 and one half inch body and head. Tail shorter. Slate color with sheen. Active day and night. Sandy loam with vegetative cover.


Rodents gnaw things. That’s what the name means, gnawers. Rodentia. They have large front teeth and small brains. Well, how much brain does it take to chew on things all day? Or all night. Most rodents are active at night at those whose walls have been invaded by some of these animals will attest. Most rodents utter small squeeks that are difficult to distinguish. However, several do make distinctive sounds and these will be outlined below.

Index to rodents

  1. Beaver and porcupine
  2. Beaver (Castor canadensis) 25 to 30 inch body, 9 to 10 inch flat tail, 30 to 60 pounds weight. It is the largest rodent in our area. Beavers live in lodges they build of logs they built in lakes that they may also have built. They chew down trees and section these into logs for dams and homes. They cut other pieces and store them under water to provide winter food; beavers eat the bark of trees. Favorite foods are aspen, birch, willow, alder, maple. When alarmed, beavers strike the water with their flat tails making a loud slapping sound. (DVG)
  3. Porcupine (Erethizon dorsatum). 25 to 30 inches including tail, heavy bodied, clumsy, coated in long hair that conceal long sharp spines. The main weapon is the tail which they can swing rapidly at an enemy. If you get porcupine spines in you see a doctor; they don’t come out easily and will work their way in deeper if not removed. Porcupines den in hollow trees. They are reportedly preyed on by fishers that flip them onto their backs to get at the unprotected bellies. Porcupines make grunts, groans, and high-pitched cries that can be heard for some distance. They are heard especially during the fall which is rutting season. Eat foliage and bark of trees, favoring hemlocks in our area. Can kill tree.


Not all squirrels live in trees. Woodchucks and chipmunks live primarily on the ground. Although vegetable matter is the main food of all rodents, some squirrels will also eat flesh or eggs.

  1. Woodchuck (Marmota monax). 20 to 25 inches including tail, 5 to 10 pounds. Hibernates October to February. Yellowish-brown to brown. Digs homes in the ground in open woods and brushy and rocky ravines. Voice is a shrill whistle, given often when alarmed.
  2. Eastern chipmunk (Tamias striatus) is 8 to 10 inches long including tail. Stripes on face, back, sides. Tail smaller than in other squirrels, runs with it straight up. Hibernates. Lives underground. Voice a sharp chuck-chuck-chuck. (DVG) Stores food. Deciduous forests and brushy areas.
  3. Red squirrel (Tamiasciurus hudsonicus). 11 to 14 inches including long, bushy tail. Reddish. Calls referred to as ‘rachet-like’. Can go on longer than you’d think anything that small had breath. Agressive. Tunnels in snow. Eats wide variety of substances. Stores seeds, nuts, cones. Mixed and coniferous forests. Nests in cavities or builds nest in branches.
  4. Eastern gray squirrel (Sciurus carolinensis). 15 to 20 inches including very bushy tail. Generally a shade of gray. Found in hardwood forests where nut trees are present, often along rivers. Stores acorns and nuts singly in small holes. Plants many trees that way. Nests in cavaties or builds in branches. Call a breathy bark.
  5. Northern Flying Squirrel (Claucomys sabrinus). 10 to 12 inches including long tail which is used for steering when gliding. Fold of skin between front and back legs serves as gliding platform. Glides from tree to tree. Nocturnal. Eats wide variety of foods. Voice high twitter or breathy squeek heard at night. Coniferous and mixed woods.

Rats and Mice

These creatures, while ecologically important, are rarely seen, heard, or detected in any way. Unless they chew on your walls while you are trying to sleep. Their trails in the snow may indicate their presence. Most have a tiny squeek as a voice.

  1. Deer mouse (Peromyscus maniuclatus) is a pretty little mouse 5 to 8 inches long, at least half of which is tail. Grayish buf to red prown with bicolored tail, lighter below. Wide variety of habitats. This is the creature that spread the hanta virus that caused the deadly four-corners disease among the Navajos a few years ago.
  2. Southern bog lemming (Synaptomys cooperi) 3 and one to 4 and one half inch body and very short tail. Heavy bodied. Brownish gray above, grayish below. Ears nearly concealed. Found in low damp bogs and heavily-vegetated meadows.
  3. Boreal redback vole (Clethrionomys grapperi) is 3 and one half to 4 and one half inches, heavy-bodied, and reddish on top with gray sides in our area. Tail 1 to 1 and one half inches. Common. Found in damp woodlands of all sorts.
  4. Meadow vole (Microtus pennsylvanicus). 3 and one half to five inches with 1 and a half to 2 and one half inch tail. Heavy body, dark brown above with variable belly. Heavily vegetated open areas near water.
  5. Muskrat (Ondatra zibethica). 10 to 14 inch head and body, 8 to 11 inch tail. Naked, scaly tail flattened on sides and used as a rudder in swimming. Build houses of marsh vegetation in variety of watery habitats. Feeds on aquatic vegetation. Adds fish, clams, and frogs to diet occasionally.
  6. Meadow jumping mouse (Zapus hudsoniius) and Woodland jumping mouse (Napaeoza insignis) are virtually identical and habitats overlap – meadow to woodland and brush. Two-toned olive body, large hind feet, and very long tail. Body and head 3 to 4 inches, tail 4 to 6 inches.
  7. In addition old world mouse and rat imports may be found nearby, not that anybody is really looking for them.


Carnivores are meat eaters. That’s what carnivore means. Bears, wild cats, wild dogs, weasels, skunks, raccoons – all these are classed as meat eaters and are found in our area. They are not the only animals that eat meat and some carnivores, especially bears, eat plenty besides meat. However, their teeth developed as meat-eating teeth.

Teeth are the hardest parts of an animal’s body and the most easily preserved in the fossel record. They may be the only record available of an animal who lived millions of years ago. Paleontologists are fond of the saying that their profession is the study of one set of teeth mating with another set of teeth to produce a slightly different set of teeth. All the animals in this group have meat-eating teeth, so they are classed as meat eaters.

  1. Black bear (Ursus americanus) is generally truly black in our area. 2 to 3 feet high at the shoulder and 5 to six feet in length. Usually small patch of white on breast. Weight 200 to perhaps 500 pounds. Shaggy fur. Hibernates. Primarily nocutnal. Eats berries, nuts, roots, insects and larvae, small mammals, eggs, honey, carrion, garbage, and anything else vaguely organic. Young are born in winter den, stay with mother a year. Voice a loud growl when angry, woofing to warn cubs, and various whines and whimpers. Found in forests and swamps. Dens usually under fallen tree, in hollow log, or sometimes cave.
  2. Raccoon (Procyon lotor). 18 to 28 inch head and body, 8 to 12 inch tail. Body ‘pepper-and-salt’. Black mask. Bushy ringed tail. Dens in hollow trees. This is another that will eat virtually anything. Wooded areas along stream and lake borders. Snarls when angry, twitters to young. Does not hibernate, but hides out during cold spells.
  3. Fisher (Martes pennanti) is weasel-like. In fact, it’s in the weasel family. 20 to 25 inches long plus a 13 to 15 inch tail. Dark brown to black rich, soft fur with frosted appearance due to white ends. Found in hardwood forests. Feeds on small mammals and some vegetable matter. One of few predators on porcupine.
  4. Shorttail weasel (Mustela erminea). 7 to 14 inches including 2 to 4 inch tail. Males larger than females. Dark brown with white underparts in summer, white in winter. Found in brushy or wooded areas not far from water. Voice a shril shriek when agitated or seizing prey.
  5. Longtail weasel (Mustela frenata). 8 to 10 and one half inches plus 3 to 6 inch tail. Males larger than females. Brown above, yellowish below in summer, white in winter with black tail tip. Found in any habitat near water. Eats mammals, or occasionally birds. Voice a shriek.
  6. Mink (Mustela vison) is 17 to 26 inches including tail. Males larger than females. Rich dark brown fur with white chin patch. Fur soft, thick. Found along streams and lakes and is an excellent swimmer. Eats small mammals, birds, and aquatic animals.
  7. River otter (Lutra canadensis) 38 to 48 inches long. Large, weasel-like, rich brown above with silvery sheen below. Feet webbed. Found along streams, lakes, but may travel miles to find another stream. Sociable and playful. Eats primarily aquatic animals. Dens in banks with entrance below water.
  8. Striped skunk (Mephitis mephitis) is 20 to 30 inches including very bushy tail. Black with varying amounts of white on long fur. Has scent gland at base of tail which produces familiar skunk smell. Permeates everything. Reportedly preyed upon only by great horned owls. Eats anything. Dens in variety of places. Sometimes chitters when angry. (DVG) Primarily nocturnal.
  9. Coyote (Canis latrans) is a recent additon to the fauna of this area. Hated by hunters who regard it as a competitor. Grayish, like a medium-sized dog. Pointed nose. Brushy tail. Found in open woodlands or cleared places in our area. Nocturnal. Primarily scavenger, though will hunt. Voice a series of yaps and yodels. Less vocal in our area than in the desert areas of the west.
    You hear it occasionally (DVG)
  10. Red fox (Vulpes fulva). Small dog-size with long, busy tail. Generally reddish, darkest on back, white on belly. Eats primarily small mammals, but also some fruits. Remember the fox and the grapes? Often makes spare dens for backup. Most active from late evening to early morning. Voice a vaguely dog-like yapping bark. Wide variety of habitats.
  11. Bobcat (Lynx rufus). Very large cat-size with short tail, black only on tip. Nocturnal and solitary. Found in swamps in forest. Eats small mammals and birds.

What, If Anything, is a Rabbit?

It was with that title that a taxonomist introduced a new theory of rabbit relationships. Previously, rabbits had been classed with rodents. Now they were put in their own order, Lagomorpha, which means nothing more profound than ‘rabbit-shaped’.

  1. Snoeshoe hare (Lepus americanus) looks and feels just like a very long-legged domestic rabbit. It turns white in winter. Distinguished from rodents by a second set of teeth behind incisors. Nocturnal. Found in forests and swamps. Will eat frozen meat. Population cycles of about 11 years.

Animals with Hooves

In our area, the only hooved animals are members of the deer family. Antlers are shed every year. Generally only males have antlers which are used in courting displays and battles, but there are some exceptions.

  1. Whitetail deer (Odocoileus virginianus). 3 to 3 and one half feet high. Weight varies from 50 pounds in small does to 400 in large bucks. Found in forests, swamps, and open brushy areas. Danger signal a loud, whistling snort. Browser eating twigs, shrugs, fungi, acorns. Gathers in groups in winter.
  2. Moose (Alces alces) is the size of a small to medium horse. In season, flat, hand-like antlers can spread up to 6 feet or more. It appears ungainly but runs and swims rapidly. It is found in forests, lakes, and swamps. Rarely heard voice: moos, grunts. Browser.

Identifiable Mammal Sounds

A few mammals do make readily identifiable sounds. Some can identify the animal as to species, others only as to group. A summary of these identification keys is presented here. Links are to the general guide to the group in which the animal is found.

image: Pixabay

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