The Long-tailed weasel is an endearing-looking species of mustelid common throughout America and southern Canada. Looking like a cute, curious, lively kitten, it is one of nature's most ferocious and relentless predators and is known as "nature's psychopath." Due to the pattern of their hunting and fearless attitude about attacking bigger animals, they are an interesting animal to study. They secure extra prey for future consumption, driven simply by their basic instincts.
Long-tailed weasels occupy a wide range, from southwestern Canada south across the United States (except parts of the southwest) then into Central America, Mexico and South America (Columbia, Venezuela, Ecuador, Peru, and Bolivia). They are found in tropical and temperate habitats in Central and North America. Their habitats range from small wooded areas to crop fields to suburban areas but do not include thick dense forests or deserts. Their nests and burrows are in rock piles, hollow logs and under barns.
These mammals are not social animals and the genders live apart except in the mating season. A male’s home range will overlap those of several females, but those of same-gender adults never overlap. These animals are very aggressive when their home ranges are intruded. They are quick, alert and agile. They hunt their prey by detecting scent or sound, then follow their victim to attack quickly, killing them with a quick bite at the base of the animal’s skull. Long-tailed weasels may be active in the daytime but are more active during the night. They are known to be noisy, usually in response to a disturbance. This species communicates among themselves through visual, sound, and scent means. Females emit an appealing scent when ready to mate. Sounds and body language are used for communicating when two weasels confront each other.
Long-tailed weasels are polygynous, which means that one male mates with multiple females. Mating takes place during mid-summer. After copulation, there is a period of delayed implantation, with the egg not beginning to develop until March, the total gestation time being around 280 days. Births are from late April through early May. The average litter size is six. At birth young weigh about 3 grams and have pink wrinkled skin with white fur. After fourteen days, their hair starts to thicken, and size-wise it is easy to tell males and females apart. At 36 days they are weaned and start eating food their mother brings back to the nest. Their mother teaches them how to kill prey and by 56 days they can kill their own prey. Females mate during their first summer, males the following spring.
Long-tailed weasels are possibly sensitive to fragmentation of habitat due to agricultural activities, so maintaining landscape connectivity is important for this species. Other threats include the drainage of wetlands and monoculture. They may also be affected both directly and indirectly by the use of pesticides, through effects on habitat, reproduction and/or food supply.
Long-tailed weasel is widespread and fairly common throughout its range but no overall population estimate is available. Currently this species is classified as Least Concern (LC) and its numbers today remain stable.
Due to what they consume, Long-tailed weasels help control populations of rabbits and rodents.