North American Wildlife ----Mustelids (weasels and related species)

Members of this family typically have elongated body shapes and short legs. Their spinal flexion aids in their ability to leap. They are "quick" but not necessarily "fast" (meaning that they have great speed for short distances or lunges). Mustelids are very carniverous and thus predatory. They range in size from the tiny least weasel to the large wolverine, and their niches, or prey sizes, vary accordingly (from mice to moose so to speak). Mustelids kill prey larger than themselves by a throat bite, and the hanging on and chewing until the animal suffocates or bleeds to death. This may leave the weasel covered in blood and has resulted in the reputation of "bloodthirsty". It is an unfair accusation for an animal that has simply developed an efficient way of killing its food.

Another behavior that leads humans to view certain predators as bloodthirsty is surplus killing. This occurs either when mothers are teaching young to kill or if the reactions of panic in the prey (usually domestic) triggers more killing reaction. Surplus killing has been documented in many predator species.

Mustelids do not hibernate or go into torpor, and must hunt all year. Their elongated shapes result in heat loss, and they must consume more calories to make up for that. The result is an animal intent on finding and killing prey.

Mustelids in temperate regions exhibit delayed implantation. Birth is in April or May, and implantation occurs from 1-3 months before birth (1 for weasel, 3 for wolverine). Actual mating may have occurred as little as a month before implantation (mink) to 9 months for other species. One male may mate with several females during the breeding season. Females are monestrous and cycle shortly after parturition. Males are larger than females (sexual dimorphism).

Mustelids are active at any time of the day or night, that is, not typically just nocturnal or diurnal. They are important as furbearers and predators, and serve important ecological roles at the top of the foodchain. They are solitary and territorial, males having larger territories than females.

Marten & Fisher

These species are cold – temperate climate species found in the northern U.S. parts of Canada and in western mountains. They are arboreal mustelids, that is, very adept tree climbers. They will often travel through trees, and can prey on birds, eggs and squirrels.

Marten (Martes americana) : The marten is found in the boreal and northern conifer or mixed forest. It is associated with deep consistent winter snow. Habitat may be conifer or mixed forest anywhere from 20 feet tall on up. An important feature however is downed woody debris on the ground. This provides habitat for voles, the marten’s chief winter food, and space to tunnel under the snow (subnivean). In summer prey includes birds and eggs, and squirrels. Marten have home ranges of 1-2 square miles. Breed in summer, litters of 2-3 born in winter. The marten is considered to be a valuable furbearer.

Fisher (Martes pennanti): This arboreal mustelid is found overlapping and south of the marten. It is range includes the mixed and northern hardwood forests of southern Canada and the northern U.S. It does not handle deep soft snow as well as the marten, and deep snow probably limits its distribution northward. This animal preys on hare, rodents, and porcupine. It is one of the few predators capable of routinely killing porcupines (by biting the face). Home ranges are 1 to several square miles. Mate in April, births in following march, litters of 2-3. Whelping dens are in hollow trees, but may have temporary dens in brush piles, woody debris etc. Considered to be a valuable furbearer.

Mink (Mustela vison): all weasel type animals in the genus Mustela are ground hunters and dwellers. This mink is primarily found in riparian habitats, and preys on crustaceans, craw fish, frogs, rodents, muskrat, and other similar sized animals of opportunity. One of the first well documented studies of predator prey relationships was done on mink and muskrat by Paul Errington. He found that predation on muskrat was highest during high muskrat densities, and negligible at low densities. Mate in March, birth in May (short delay). 5-8 young.

Weasels (Mustela erminea and frenata): the short tailed and long tailed weasels are similar in appearance but differ in size. The short-tailed is found further north than the long-tailed, but they overlap in the northern U.S. both turn white in winter where winter snow is typical. Weasels typically prey on rodents and ground nesting or feeding birds. The short-tailed is considered to have more valuable winter fur. Home ranges are from 5 to 125 acres. Litters of 3-10 born in spring. Mate in summer.

Badger (Taxidea taxus): the badger is fossorial, or burrowing, and is found in the mid-west and western portion of the U.S. and part of Canada. The badger preys on rodents and snakes. It’s thick layer of subcutaneous fat make it resistant to rattlesnake bites. It has remarkable digging power, and can dig rodents out of their burrows very efficiently. These animals are solitary, and females have litters of 2-5. Summer breed, spring birth.

Black footed ferret (Mustela nigripes): This burrowing ferret is closely associated with large prairie dog towns, and is an endangered species. Few can be found in the wild, and intensive efforts are under way to reestablish their populations. Prairie dogs are their main prey. The ferrets are solitary and territorial except during spring breeding season . 4 young born in summer (no delay).

River otter (Lutra canadensis): the river otter is found in aquatic and marine habitats in the NE, SE, NW and across most of Canada. Territories are large and encompass watersheds. Males are solitary except during breeding (march –April). Excellent divers and swimmers, predators of fish and shell fish. Scent mark territories. Defecate in certain spots ("latrine"). Rolling behavior grooms fur and maintains insulating air spaces. Protected furbearer. 2-3 pups born in spring after long delay of implantation (spring mating)

Wolverine (Gulo gulo): Largest terrestrial mustelid. Rare in US (20 in Montana). More common in Alaska and Canada. Solitary except during summer breeding. (births in winter, 2-3). Cover extensive territories (may travel 50 mile in a day). May kill large prey, but mostly scavenge other predator kills. Very inquisitive, powerful and can be aggressive.

Striped skunk (Mephitis mephitis): Skunks are common throughout the US. Expanding northward. Other types of skunks are the hog-nosed and spotted. All are mostly nocturnal and omniverous, eating many insects and larvae. Non-aggressive. Breed in spring and give birth after 8 weeks (no delayed implantation). Litter = 6. Rabies may be common.

Raccoon & related species - family Procyonidae

The raccoon in the most common of this group in N. America. The coatimundi is found in Central and South America. The ring-tailed cat is found in mexico and the American southwest.

The raccoon is an omnivore with mostly nocturnal patterns. It may be found in just about every habitat available in N. America, especially human altered habitats. Raccoon density is higher in suburbs than in any wild habitat, using storm sewers for travel lanes, and garbage & gardens for food. Raccoons mate from February to June and give birth to 2-7 young 2 months later. The young stay with the mother consuming only milk for 2-3 months. Raccoons in the wild defecate at latrine sites. Feces may carry roundworms that may be fatal in humans. Raccoons also may carry rabies (currently a strain of raccoon rabies along the east coast.)