Weasels might be small, but a closer examination reveals their intriguing lives. Despite their diminutive stature, this list of weasel facts reveals that they possess impressive hunting skills that enable them to live in diverse landscapes. For instance, three weasel species live in North America: least, long-tailed, and short-tailed.
Read on for more facts that explore their traits and this animal's significant contribution to our global ecosystem.
Regarding the weasel diet, weasels typically eat rats, mice, voles, and rabbits, which are abundant in their natural habitats. Moreover, they also have a versatile diet1, consuming frogs, birds, and bird eggs.
The weasel (such as the long-tailed weasel) has a slender body that can fit into tiny crevices or holes. Moreover, weasels' bodies are cylindrical, allowing them to enter tight spaces and catch unsuspecting animals like rats or rabbits.
At night, weasels emerge and cover large areas. Their excellent hearing and sharp sense of smell enable them to locate prey hidden in vegetation or underground.
The weasel's nocturnal behavior is a survival strategy. These mammals cover vast distances on land and water at night, darting through undergrowth or creeping through towering grass. Due to their elusive nature, humans rarely see this behavior.
Next on our list of weasel facts: Weasels possess heightened vision and hearing, enabling them to hunt efficiently. For instance, the weasel has eyes at the front of its face that provide exceptional depth of field. These creatures can size up their environment to find prey, especially at night when they become active.
Meanwhile, their small, round ears allow them to detect minor sounds, such as a mouse rustling in the undergrowth or a vole burrowing under snowy blankets. Additionally, these senses alert the weasel to nearby predators and allow it to retreat quickly.
The weasel is a surprising predator due to its size. Impressively, they can take down much larger prey. Its slender body allows it to access the hiding places of larger animals, and it swiftly attacks, leaving its target with little chance of escape.
The weasel's agility, quick reflexes, strong jaws, and sharp teeth make it a fearsome hunter. Moreover, weasels have a fast metabolism, which requires them to eat about 40% of their body weight daily.
Sometimes, weasels do a "war dance," a hunting technique that confuses and disorients their prey, like rabbits. The Mustelidae family, including stoats and ferrets, also perform similar dances.
However, the weasel often breaks into dance even without any potential prey in sight. Researchers have yet to determine the exact reason for these impromptu performances. Some suggest weasels dance to polish their hunting skills. On the other hand, others propose weasels are entertaining themselves.
Additional fun fact: Did you know that the African striped weasel is among the smallest mammal carnivores on the continent?
Another interesting fact about weasels is that they also have a small pouch beneath their tails containing a yellowish fluid, a self-defense tool similar to skunks. When threatened, weasels instinctively spray around two tablespoons of this fluid at their enemy.
The little mammal also has an accurate aim, spraying its attacker with a stinky liquid, which remains in the air long after the weasel escapes, warning other predators.
While not harmful, the scent creates maximum impact. Moreover, some weasels spray a stinkier liquid than others. Factors such as diet and health can influence this variation.
Every winter, the ermine, or short-tailed weasel, changes its appearance. As the days become shorter, the ermine sheds its brown fur and wears a white coat. This white coat provides a striking spectacle against snowy backgrounds. Additionally, this new coat acts as a camouflage for the ermine, making it an undetectable predator in wintery landscapes2.
The ermine transforms in response to the decreasing daylight hours, a process called photoperiodism. This adaptive strategy is common in regions with heavy snowfall during winter. Moreover, this transition starts in autumn and prepares the ermine for the harsh winter months. Besides camouflage, the ermine's coat and denser fur insulate its body.
Weasels observe delayed implantation during breeding. Following fertilization, the embryos of weasels remain dormant for several months before the female implants them in the uterus. This behavior ensures the kits, or baby weasels, are born under optimal conditions. (Female weasels measure 15 to 18 centimeters long with a tail of 4.5 centimeters, while males have a two-inch tail).
Unlike most animals with a single mating season, weasels have multiple mating seasons throughout the year3, preferring spring and summer.
During mating, male weasels, or 'hobs,' bite the neck of female weasels, or 'jill,' to start the process. After mating, the hob leaves the Jill or potential kits.
Once Jill is pregnant, she carries the kits approximately 35 days after the embryo's implant. However, she may have had the embryos for several months, resulting in a gestation period of 2 to 11 months.
Most weasels live everywhere in the world; they are resilient creatures able to adapt to changing environments. For example, the least weasel, long-tailed weasel, Siberian weasel, and tropical weasel are species of "Least Concern," according to the International Union for Conservation of Nature (IUCN).
However, not all weasels are equally fortunate4. The IUCN has classified the Japanese weasel and mountain weasel as "Near Threatened" due to their shrinking habitats, resulting from urbanization and agricultural expansion. The Malayan weasel is also vulnerable and must avoid hunters in addition to habitat loss.
Fortunately, strengthened laws, habitat conservation, and public education have begun making a difference in weasel conservation. For example, protecting the Malayan weasel is a legal obligation in Malaysia. Why do weasels need protection? They are invaluable to the ecosystem, for they control rodent populations.
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Related: To further explore the animal kingdom, check out some of the other animals that start with W.
McDonald, R. A., Webbon, C. C., & Harris, S. (2000). The diet of stoats ( Mustela erminea ) and weasels ( Mustela nivalis) in Great Britain. Journal of Zoology, 252(3), 363–371.
Mills, L. S., Zimova, M., Oyler, J. W., Running, S. W., Abatzoglou, J. T., & Lukacs, P. M. (2013). Camouflage mismatch in seasonal coat color due to decreased snow duration. Proceedings of the National Academy of Sciences, 110(18), 7360–7365.
Deanesly, R. (2009). The Reproductive Cycle of the Female Weasel (Mustela nivalis). Proceedings of the Zoological Society of London (1944), 114(3), 339–349.
Jachowski, D. S., Kays, R., Butler, A., Hoylman, A. M., & Gompper, M. E. (2021). Tracking the decline of weasels in North America. PLOS ONE, 16(7), e0254387.