Weasels, Martens, Otters, Minks, and Ermines of New York

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About Weasels

River Otter

Weasels and all their variants make up the Mustelidae family, a large and diverse branch of carnivorous mammals that ranges from the tiny Sea Otter to the Wolverine. Characterized by their long slender bodies, short limbs, short, round ears, thick fur, and sharp teeth, these efficient predators are can be found all over the world (with the exception of Australia and Antarctica), and vary in habitat, from primarily aquatic species, such as the Sea Otter on the west coast of the US to the arboreal Marten, which can be found in our region. Mustelids are primarily carnivorous although some have been known to supplement their diets with plant matter. Oddly enough the smaller of the weasels often attack and kill prey, such as rabbits and birds, much larger in size.

Mustelid fur is prized for its thickness and texture. The Mink, also found in this region, being one of the most prized for its coat. Trapping weasels for fur has been a human tradition since prehistoric times, was one of the biggest economies during colonial America, and still continues today, legally and illegally, in New York State.

Some Interesting Facts:

♦ A common household pet, the ferret, is a Mustelid, domesticated 2,500 years ago in Europe.

♦ Weasels have been brought into many non-native habitats and a non-destructive means for controlling rabbit populations.

♦ A group of weasels can be called a boogle, gang, pack, and confusion. Isn’t English grand?!

♦ Weasels are mostly nocturnal, active at night, resting by day.

♦ Weasels have glands that excrete a foul-smelling substance when they are under attack. Their nimble bodies also help them avoid predators, which is how we have the saying “weasel out of” something.

♦ Despite many websites stating otherwise, weasels are not poisonous and do not have venomous saliva. That is a myth. But if you are bitten, you should seek medical attention because of the potential for salmonella or rabies.

Weasel / Otter Books and Field Guides

Identification Guide for Weasel-like Animals of New York

American MartenAmerican MartenFind more images

American Marten
(Martes americana)

AKA: Pine Marten (incorrectly)

Identifying characteristics: A small, weasel-like mammal (long body, short legs, long neck, triangular head, protruding ears, long whiskers) that is usually a light to dark brown with paler gray head, buff throat and cream under parts. The legs and long bushy tail tend to be a darker color than the rest of the body. The fur is generally shiny. The head and face appear cat-like and have dark lines that run from the muzzle past the inner corners of their eyes. Their ears are large and the snout is pointed.

Size: Up to 12-24 inches in length (not including their tails, which is 30% of their total length) and weigh up to 3 pounds. Males are larger than females by more than 20%.

Habitat: Mature forests, pine forests with plenty of debris and little outside disturbance. Their dens are usually in hollow trees, woodpecker holes or abandoned burrows.

Food: Omnivorous. Small mammals, birds, insects, fruits, nuts, carrion, with voles and red squirrels being their preferred food. Often found hunting or scavenging on the ground for rodents. Martens often cache leftover food.

Vocalization: Huffs, chuckles, pants, screams, whines, eeps.

Predators: Humans for pelts, possibly owls.

Reproduction: Litter size averages 3 with only 1 litter a year. Mating season is in summer.

Other Info.: Primarily nocturnal and solitary. Martens are arboreal, spending a lot of time in trees, where they can move quite impressively. Martens will often chase and catch red squirrels around the tree tops in an amazing display of acrobatics. A Marten’s territory may reach 3 square miles.

Distribution

Distribution

Northern-most counties and old growth forests.

Status: none

Tracks

Martin Tracks

Marten tracks, like other Weasel-family tracks are twin prints. The prints tend to overlap when walking and form a straight line when running. Prints are 1.4-1.6, with a walking stride of 6-9 inches. Claws are present and during the winter fur grows in between the toes, possibly obscuring the pads. Trails are usually zigzags, with leap gaps. Irregular track patterns are almost always present due to the animal’s erratic foraging strategy.

ErmineErmine winter coatFind more images

Ermine
(Mustela erminea)

AKA: Stoat, Short-tailed weasel

Identifying characteristics: A small, weasel-like mammal (long body, short legs, long neck, triangular head, protruding ears, long whiskers) with brown fur on top and white fur on the the undersides including the neck and lower jaw. In winter they tend to turn completely white, except for the black tips of their tail.

Size: From 6 to 12 inches in length (not including their tails, which make up 35% of their total length) and weighing up to 4 ounces. Males are roughly double the size of females.

Habitat: Coniferous and other forests, marshes, open fields (close to forests), brushland. Dens can be crevices under tree roots, rocks or logs and sometimes in abandoned burrows. Dens are usually at or below ground level.

Food: Carnivorous. Specialize in small mammals, but will often eat birds, eggs, fish, lizards, snakes, frogs, and insects. Ermine often cache leftover food. Females tend to hunt within their prey’s burrows, while males hunt on the ground.

Vocalization: Generally not vocal. Grunts, hisses, chatters, whines.

Predators: Humans, larger mammals and birds.

Reproduction: Litter size average 4-9 (sometimes reaching 18) with 1 litter a year. Mating season is in late spring, early summer.

Other Info.: They are diurnal, often active both day and night. They are capable climbers and swimmers. They often investigate all the crevices and holes when moving about, looking for prey. They will periodically stand upright to check their surroundings and to look out for predators. They are well adapted for snow. Very solitary animals.

Distribution

Complete distribution

Found throughout the state and neighboring states.

Status: none.

Tracks

Ermine tracks

Ermine prints are similar to other weasel prints in that they are often paired. Hind prints usually fall within the fore prints. The ermine’s 5th toe is obscured. The hind print is longer than the fore print. Prints are up to an inch wide and the stride is 4-5 inches. Claws present. In the diagram above, green represents the longer hind print. Small tunnels in the snow may be left by ermines diving for prey. Irregular track patterns are almost always present due to the animal’s erratic foraging strategy.

FisherFisherFind more images

Fisher
(Martes pennanti)

AKA: Fisher cat, Pekan

Identifying characteristics: A small, weasel-like mammal (long body, short legs, long neck, triangular head, protruding ears, long whiskers) that tends to look stockier than other weasels due to its fluffy fur. They are medium to dark brown with either gold or silver hoariness around the top of the head and shoulders. The legs and tail are black. A cream-colored patch may be present on the neck or chest.

Size: From 30 to 45 inches in length (not including their tails, which make up 33% of their total length) and weighing up to 8 pounds. Males are roughly 20-40% larger than females.

Habitat: Coniferous or deciduous forests with a closed canopy. Hollow trees are preferred dens and habitats with plenty of hollow trees are preferred. Fishers will also create dens in the snow for winter and connect them with tunnels.

Food: Carnivorous. Mice, porcupines, snowshoe hares, squirrels, birds, and other small mammals. Sometimes found eating carrion. They will often invade their prey’s burrows. The Fisher will often prey upon porcupine, attacking its face until it collapses from its wounds. It will then roll it over and chow down! A porcupine is more than enough food so it will cache some for later.

Vocalization: Various hisses, grunts and one distinct call that sounds like a child screaming.

Predators: Humans. The young are preyed upon by raptors, bobcats, coyotes, American Martens and other larger predacious mammals.

Reproduction: Litter sizes average 3, with one litter every 1 year. Young stay with the mother for up to 5 months. Mating season is in late winter through early spring.

Other Info.: Solitary and nocturnal, but may be active during the day. Is a very good climber and is often found in trees. Decent swimmer.

Distribution

Fisher distribution

Found in the north-eastern-most counties.

Status: none

Tracks

Fisher tracks

Fishers have 5 toes and claws and, like other weasels, their prints are paired when walking and the fore prints overlap slightly with the hind prints. Their prints are wide (2 inches) with a 30 inch stride. In the diagram above, green represents the slightly larger hind print.

Irregular track patterns are almost always present due to the animal’s erratic foraging strategy.

Long-Tailed WeaselLong-Tailed WeaselFind more images

Long-Tailed Weasel
(Mustela frenata)

Identifying characteristics: A small, weasel-like mammal (long body, short legs, long neck, triangular head, protruding ears, long whiskers) with cinnamon-brown fur and yellow-cream under parts, including their chin. They shed their fur twice a year and in winter may have a white coat. Their tail is long and bushy with a black tip. Their feet are brown.

Size: From 8 to 10.5 inches in length (not including their tails, which make up 50% of their total length) and weighing up to 1 pound. Males are twice as large as females.

Habitat: Lightly wooded areas, fields and crops. Dens can be hollow trees, stumps, crevices in rocks, under man-made structures, or the burrows of their prey.

Food: Carnivorous. Females specialize in small rodents and voles, while the males tend to take on larger prey, like cottontail rabbits. They will also prey upon birds, reptiles, insects and earthworms when available. Foraging for fruits occurs in summer.

Vocalization: Often describes as noisy. Grunts, hisses, chatters, whines.

Predators: Humans, larger mammals, snakes and birds.

Reproduction: Litter size average 6 with 1 litter a year. Young leave their mother after 60 days. Mating season is mid-summer.

Other Info.: They are diurnal, often active both day and night. They are capable climbers and swimmers. They often investigate all the crevices and holes when moving about, looking for prey. They will periodically stand upright to check their surroundings and to look out for predators. They are well adapted for snow. They will hunt in a zig-zag pattern checking burrows for prey. They will often kill more than they can eat and store any leftovers.

Distribution

Complete distribution

Found throughout the state and neighboring states.

Status: none

Tracks

Long-Tailed Weasel tracks

Their prints are similar to other weasel prints in that they are often paired. Hind prints usually fall within the fore prints. The 5th toe is obscured. The hind print is longer than the fore print. Prints are 3/4 inch wide and the stride is 12 inches. In the diagram above, green represents the longer hind print. Claws present.

Irregular track patterns are almost always present due to the animal’s erratic foraging strategy.

MinkMinkFind more images

Mink
(Mustela vison)

AKA: American mink

Identifying characteristics: A small, weasel-like mammal (long body, short legs, long neck, triangular head, protruding ears, long whiskers) with soft, glossy medium to dark chocolate brown fur with a cream patch on their chin. Their feet and tip of their bushy tail are near black. Their feet are partially webbed, an adaptation to their near-aquatic habitat.

Size: From 19 to 28 inches in length (not including their tails, which make up 35% of their total length) and weighing up to 3 pounds. Males are roughly double the size of females.

Habitat: Near streams, lakes and marshes, often building their dens along the shore. They will also use abandoned muskrat beaver or rabbit dens. They frequently move to newer dens.

Food: Carnivorous. Primarily fish, crayfish, and small mammals such as mice. They are opportunistic and will capture and consume waterfowl, reptiles and amphibians.

Vocalization: Grunts, hisses, chatters, whines, purrs.

Predators: Humans, coyotes, foxes, owls.

Reproduction: Litter size averages 4 with 1 litter a year. Mating season is in late winter, early spring.

Other Info.: They are diurnal and somewhat solitary. Unlike other weasels, they tend to stay in family groups during the summer months. They were frequently trapped for their fur coats, but since being raised in fur farms to cater to the clothing industry, wild populations seem to be stable. Well adapted for swimming and able to dive to depths over 15 feet. Marks its territory with a strong musk secreted from its anal gland, making this one stinky animal. Minks, like other weasels are active year-round and do not hibernate.

Distribution

Complete distribution

Found throughout the state and neighboring states.

Status: none

Tracks

Mink Tracks

5-toed tracks with claws present. Webbing and heal print may not be present unless the track is clear.  Their prints are similar to other weasel prints in that they are often paired.  Hind prints usually fall within the fore prints. Prints are 1-1.5 inches wide with the hind prints (shown in green) considerably longer. The stride is roughly 12-15 inches. Zig-zag track pattern. Tunnels in snow are a good sign of weasel activity.

River Otter

River Otter

Find more images

River Otter
(Lontra canadensis / Lutra canadensis)

Identifying characteristics: A relatively large, weasel-like mammal (long body, short legs, long neck, triangular head, protruding ears, long whiskers) with short and thick, glossy medium to dark brown fur (looks darker when wet). Their necks are a lighter color, like tan or golden brown. Highly specialized for aquatic living, their feet are webbed and they are streamlined for swimming. Their ears are very small and their nostrils can close under water. The tails are thick, tapered and rudder-like. The whiskers are white and very prominent.

Size: From 3 to 4 feet in length (not including their tails, which make up 40% of their total length) and weighing up to 30 pounds. Males are slightly larger than females.

Habitat: Near permanent streams, lakes and marshes with abundant food supply and unpolluted water. Since shoreline is where they set up dens, development of these shorelines has greatly reduced their available habitat. Their home range is large, reaching miles along a stream. Dens are the burrows of other mammals, or in hollow logs. Dens usually have a second (underwater) entrance and nests of grass.

Food: Carnivorous. Primarily fish, crayfish, crabs, amphibians, turtles. Sometimes birds, eggs, small mammals, and plants. Because the vast majority of their diet comes from the water, water pollution is a great threat to the health of otters.

Vocalization: Grunts, whistles, chatters, whines, snorts, screams.

Predators: Humans, bobcats, coyotes, foxes, bears, birds of prey.

Reproduction: Litter size averages 2-3 with 1 litter a year. Young stay with the family until 8 months to a year. Mating season is in late winter, early spring.

Other Info.: They are diurnal and mostly solitary animals, though maternal bonds are strong and young stay with their families for up to a year. There is frequent contact and play with each other. Otters are superb swimmers and able to stay submerged for up to 8 minutes at a time. Quick and agile in water, they use it to hunt and evade prey. Their long whiskers are sensitive to touch and used while foraging underwater.

Distribution

Distribution

Can be found scattered throughout the state although more frequent where streams are free from human activity. Missing from some western-most regions.

Status: none.

Tracks

Otter tracks

5-toed tracks with pointed toes (due to lack of space between toe and claws). Prints are about 3 inches wide with the toes spread out, but webbing not always visible. The stride is from 11 inches to 2 feet when running. Sometimes the tail will drag. Their prints are similar to other weasel prints in that they are often paired.

Mud or snow slides running down the bank of a stream is a good sign of otter activity.

In the above diagram, tracks as well as the characteristic playful slide is shown.

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