Japanese Weasel

About this species

Weight

Males average about 400g and may reach 800g

Diet

Rodents, amphibians, reptiles, birds, eggs, fish, insects and crustaceans

Habitat

Forest, wetland, farmland and settled landscapes

Range

Native to Honshu, Shikoku, Kyushu and nearby islands

The Japanese weasel is an endemic, long-bodied mustelid with short legs and a tail shorter than its head-and-body length. Adult males average roughly 400g and can reach 800g, while females are lighter (Habitat-Associated Dietary Plasticity in the Japanese Weasel, 2025). It is naturally distributed across Honshu, Shikoku, Kyushu and nearby islands, with additional island populations created by introductions (Sato et al. 2025).

Japanese weasels use a broad range of habitats, including forests, wetlands, farmland and suburban landscapes. They hunt rodents, amphibians, reptiles, birds, fish and crustaceans, raid nests for eggs and young birds, and may take fruit when animal prey is scarce; surplus food can be cached (Animal Diversity Web species account). Their flexible diet helps them persist in modified settings, although local prey use varies markedly with habitat and season (Habitat-Associated Dietary Plasticity in the Japanese Weasel, 2025).

Description: Wildlife of Japan guide, Wildlife of Everywhere (wildlifeofeverywhere.com)