Animal Diversity Web

Ge­o­graphic Range

The range of the long-tail weasel in­cludes most of North Amer­ica, ex­tend­ing from just north of the United States-Cana­dian bor­der and south to Cen­tral Amer­ica to north­ern South Amer­ica (Baker, 1983). Long-tailed weasels have the largest dis­tri­b­u­tion of any mustelid in the West­ern Hemi­sphere.

• Biogeographic Regions
• nearctic
  • native
• neotropical
  • native

Habi­tat

Long-tailed weasels are found in tem­per­ate and trop­i­cal habi­tats in North and Cen­tral Amer­ica. These habi­tats range from crop fields to small wooded areas to sub­ur­ban areas. They are not found in deserts or thick, dense forests. Their bur­rows and nests are in hol­low logs, rock piles, and under barns. Some­times in­stead of build­ing a new nest, long-tailed weasels take over the bur­row of one of their prey (Baker, 1983).

• Habitat Regions
• temperate
• terrestrial

• Terrestrial Biomes
• chaparral
• forest
• scrub forest

Phys­i­cal De­scrip­tion

Long-tail weasels have a long slen­der body, sim­i­lar to other weasels. On av­er­age, males are larger than fe­males. These weasels have long, bushy tails that are about 50% of their total body length. Body length varies be­tween 330 and 420 mm in males and 280 to 350 mm in fe­males, tail length is from 132 to 294 mm in males, and 112 to 245 mm in fe­males. Long-tailed weasels have a small, nar­row head with long whiskers. They also have short legs. The fur is com­posed of short, soft un­der­fur cov­ered by shiny guard hair. They are cin­na­mon brown in color with white under parts that have a yel­low tinge. Twice a year these weasels shed their fur, once in the spring and again in the fall. This process is con­trolled by pho­tope­riod. The coat of an­i­mals in north­ern pop­u­la­tions is white in the win­ter and brown in the sum­mer, while those in south­ern pop­u­la­tions are brown year round (Baker, 1983).

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger

• Range mass

  80 to 450 g

  2.82 to 15.86 oz

• Average mass

  150.6 g

  5.31 oz

• Range length

  203.0 to 266.0 mm

  7.99 to 10.47 in

• Average basal metabolic rate

  1.344 W

  AnAge

Re­pro­duc­tion

• Mating System
• polygynous

Mat­ing for long-tailed weasels oc­curs in the mid-sum­mer months. After cop­u­la­tion, im­plan­ta­tion is de­layed and the egg does not begin to de­velop until March, mak­ing the total ges­ta­tion time around 280 days. Birth oc­curs from late April to early May, and the av­er­age size of the lit­ter is six. At birth young weasels weigh about 3 grams. They are pink with wrin­kled skin, and they have white fur. At four­teen days, the white hair be­gins to thicken, and size dif­fer­en­ti­a­tion makes it easy to tell males from fe­males. At 36 days young weasels are weaned and can eat food brought back to the nest by the mother. They learn how to kill prey from the mother and by 56 days old they are able to kill prey on their own. Fe­males mate in their first sum­mer, but males wait until the fol­low­ing spring (Baker, 1983).

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • internal
• viviparous
• delayed implantation

• Breeding interval

  Long-tailed weasels mate once each year.

• Breeding season

  Young are born from April to May.

• Range number of offspring

  4.0 to 8.0

• Average number of offspring

  6.2

  AnAge

• Range gestation period

  337.0 (high) days

• Average gestation period

  280.0 days

• Average weaning age

  36.0 days

• Range age at sexual or reproductive maturity (female)

  3.0 to 12.0 months

• Range age at sexual or reproductive maturity (male)

  3.0 to 12.0 months

At birth, young weasels weigh about 3 grams. They are born help­less, with eyes closed, and with pink, wrin­kled skin and white fur. At four­teen days their white fur be­gins to thicken, and size dif­fer­en­ti­a­tion makes it easy to tell males from fe­males. At 36 days old young weasels eyes open and they begin to be weaned and to eat foods brought back to the nest by their mother. They learn how to kill prey from the mother, and by 56 days they are able to kill prey on their own. Soon after they be­come in­de­pen­dent.

• Parental Investment
• altricial
• female parental care

Lifes­pan/Longevity

Many long-tailed weasels die be­fore reach­ing one year old. How­ever, once they have reached adult­hood they may live for sev­eral years. The lifes­pan of long-tailed weasels in the wild is not well known.

• Average lifespan
  Status: captivity

  8.8 years

  AnAge

Be­hav­ior

Long-tailed weasels are not so­cial an­i­mals; the sexes live apart from each other ex­cept dur­ing the mat­ing sea­son. One male's home range may over­lap sev­eral fe­male home ranges, but home ranges of adults of the same sex never over­lap. Weasels ex­hibit very ag­gres­sive be­hav­ior to in­trud­ers of their home ranges.

Long-tailed weasels are quick, agile, and alert an­i­mals. They are good climbers and swim­mers.

Long-tailed weasels hunt their prey by pick­ing up a scent or sound. They then fol­low the an­i­mal and make a quick at­tack. They kill their prey by a quick bite to the base of the skull.

While long-tailed weasels can be ac­tive dur­ing the day, they are more ac­tive at night. These weasels are also known to be noisy an­i­mals, but the noise is usu­ally in re­sponse to some type of dis­tur­bance (Baker, 1983).

• Key Behaviors
• diurnal
• nocturnal
• motile
• solitary
• territorial

Com­mu­ni­ca­tion and Per­cep­tion

Long-tailed weasels com­mu­ni­cate among them­selves with vi­sual, sound, and scent cues. Fe­males emit an at­trac­tive scent when they are ready to mate. Body lan­guage and sounds are used to com­mu­ni­cate when weasels con­front each other.

Long-tailed weasels have well-de­vel­oped senses of sight, hear­ing, and smell, which al­lows them to be ef­fi­cient and sen­si­tive preda­tors.

• Perception Channels
• tactile
• chemical

Food Habits

Main prey are small ro­dents. Fe­males, with smaller bod­ies, have bet­ter suc­cess in hunt­ing small ro­dents be­cause their bod­ies can fit in­side the small ro­dent bur­rows. Males pur­sue larger an­i­mals, such as east­ern cot­ton­tail rab­bits. While mam­mals are the food of choice, these weasels eat a wide range of food, from birds to rep­tiles, and in the sum­mer their diet in­cludes fruits and berries (Baker, 1983).

• Primary Diet
• carnivore
  • eats terrestrial vertebrates

Pre­da­tion

Long-tailed weasels are feisty and ag­gres­sive and will threaten an­i­mals much larger than them­selves. They may be preyed upon by larger an­i­mals, such as large owls, coy­otes, or large snakes, such as east­ern mas­sas­auga rat­tlesnakes. They are es­pe­cially vul­ner­a­ble to pre­da­tion as young.

• Known Predators

  • owls (Strigiformes)
  • coyotes (Canis latrans)
  • rattlesnakes (Crotalidae)
  • eastern massasauga rattlesnakes (Sistrurus catenatus)

Ecosys­tem Roles

Long-tailed weasels help to con­trol pop­u­la­tions of ro­dents and rab­bits.

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

The pelts of long-tailed weasels were avail­able in the fur trade but were not a pop­u­lar com­mod­ity. Long-tailed weasels are good mousers and rat­ters, so farm­ers do not mind hav­ing weasels around their farms be­cause they elim­i­nate these pests (Baker, 1983).

• Positive Impacts
• body parts are source of valuable material
• controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Long-tailed weasels are known to raid poul­try flocks (Baker, 1983).

Con­ser­va­tion Sta­tus

Long-tailed weasels are wide­spread and fairly com­mon through­out their range.

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

Toni Lynn Newell (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Baker, R.H. 1983. Michi­gan Mam­mals. Michi­gan State Uni­ver­sity Press. United States of Amer­ica.

"An­i­mal Life His­to­ries Data­base" (On-line).

Ruff, S., D. Wil­son. 1999. The Smith­son­ian Book of North Amer­i­can Mam­mals. Wash­ing­ton [D.C.]: Smith­son­ian In­sti­tu­tion Press in as­so­ci­a­tion with the Amer­i­can So­ci­ety of Mam­mal­o­gists.