An American mink defiantly protects its recent catch of a meadow vole alongside the marsh at Great Meadows National Wildlife Refuge.
The American mink (Neovison vison) is native to North America, although its range has spread to many parts of Europe and South America. Since the extinction of the sea mink, the American mink is the only living member of the genus Neovison. The American mink is a carnivore that feeds on rodents, fish, crustaceans, frogs, and birds. It kills vertebrate prey by biting the back of the head or neck as seen in this photograph. The meadow vole (Microtus pennsylvanicus) captured here, is one of the American mink’s primary food sources throughout its range including Canada, Alaska, and the northern United States.
The American mink has a long body which allows the species to enter the burrows of prey. Its streamlined shape helps it to reduce water resistance when swimming and the thick underfur and oily guard hairs render its coat water-resistant. In warm water (24 °C or 75 °F), the American mink can swim for three hours without stopping. However, in cold water it can die within 27 minutes. It generally dives to depths of 12 in (30 cm) for 10 seconds, though depths of 3 m lasting 60 seconds have been recorded. It typically catches fish after five- to 20-second chases. American mink molt twice a year, in spring and autumn. The fur does not turn white in winter.
Males measure 13–18 in (34–45 cm) in body length, while females measure 12–15 in (31–37.5 cm). The tail measures 6–10 inches (15.6–24.7 cm) in males and 6–8 in (14.8–21.5 cm) in females. In winter, males weigh 1–3 lb (500–1,580 g) and females 1–2 lb (400–780 g). Maximum weight is achieved in autumn.
The summer fur is generally shorter, sparser and duller than the winter fur. The thick underfur and oily guard hairs render the pelage water-resistant, with the length of the guard hairs being intermediate between those of otters and polecats, thus ind