Weasels are small, agile predators known for their quick movements and elusive nature. These slender mammals navigate their environments with speed and precision. They are efficient hunters of small prey, playing a role in many ecosystems.
Physical Characteristics and Classification
Weasels have elongated, slender bodies, short legs, and small, flattened heads with long, flexible necks. A pointed tail and dense fur cover their sleek form. Weasels vary in size; the least weasel measures 20 to 27 centimeters, while larger long-tailed weasels can range from 28 to 56 centimeters. Males are usually larger than females.
Their fur is often chestnut-brown or reddish-brown on the upper parts with white or yellowish underparts. Many weasel species in colder northern regions change to a completely white coat in winter to blend with snow. Some species, like the long-tailed weasel and stoat, retain a distinct black tip on their tail even when their fur turns white. Weasels belong to the family Mustelidae within the order Carnivora, which also includes badgers, otters, and wolverines. Most are classified within the genus Mustela, though some, including the long-tailed weasel, have been reclassified into Neogale.
Habitat, Diet, and Hunting Strategies
Weasels inhabit diverse environments globally. They can be found in forests, grasslands, farmlands, and even suburban areas, preferring habitats with ample cover and a rich supply of small prey. Their distribution spans Europe, North America, much of Asia, and parts of South America and North Africa, though they are absent from Australia and Ireland. Weasels often establish dens in abandoned burrows, hollow logs, or rock piles, lining them with vegetation and fur.
As carnivores, weasels primarily consume small vertebrates, with rodents like mice, voles, rats, and squirrels forming a significant portion of their diet. They also opportunistically hunt small birds, bird eggs, reptiles, amphibians, earthworms, and insects. Weasels maintain a high metabolism, requiring them to eat roughly one-third to half of their body weight daily. Their slender bodies are well-suited for pursuing prey directly into underground burrows and tunnels.
Weasels employ agile and precise hunting techniques. They often use a “stalk and pounce” method, stealthily approaching prey before delivering a swift, fatal bite to the back of the neck or base of the skull. Their ability to squeeze into tight spaces and navigate dense vegetation allows them to surprise targets. While they prefer fresh prey, weasels sometimes “surplus kill,” storing excess food in their dens for later consumption.
Weasel Behavior and Diversity
Weasels lead solitary lives, interacting with others primarily during mating seasons or when raising young. They are territorial animals, marking and defending home ranges that vary in size based on food availability and species. Weasels are active year-round and can exhibit both nocturnal and diurnal behaviors, adapting activity patterns to climate and season. Their agility extends to climbing trees and swimming, aiding hunting.
Communication among weasels involves vocalizations and body language. They produce high-pitched screeches to warn off predators or attract attention, and chitters for communicating about food or social status. Whines can indicate distress, while hisses convey aggression or threat. Weasels also use their bodies to express intentions, such as puffing up fur and arching their backs when threatened, or stretching out for relaxation. Scent marking with anal gland secretions is another method to establish territorial boundaries.
The term “weasel” encompasses several species with shared common traits. Prominent species include the Least Weasel (Mustela nivalis), recognized as the smallest carnivore. The Long-tailed Weasel (Neogale frenata) is widespread across the Americas. The Short-tailed Weasel (Mustela erminea), also known as the stoat or ermine, is found throughout northern temperate and arctic regions. While visually similar with slender builds and short legs, distinctions like a black tail tip help differentiate these species.