Japanese weasel

Characteristics

A brown weasel. It is characterized by dark brown around the nose. Males and females differ in body size by about 10 cm, with males being larger. The torso is slender and the legs look short. The tail is rather thick and bushy. It also swims in rivers with a web between its fingers.

Some areas have been artificially released to get rid of rats.

How to distinguish Japanese Weasel and Korean Weasel

The Japanese weasel and Korean weasel look very similar. Korean weasels used to be naturally distributed only in Tsushima, but now they can also be seen in Honshu.

The distinguishing point is the length of the tail, and if the length of the tail is longer than half the length of the body, it is a Korean weasel. Also, the body color of the Japanese weasel is dark brown, while that of the Korean weasel is slightly pale brown. For details, the Ministry of the Environment summarizes the points of how to distinguish.

Reference site: [How to distinguish Korean weasels and white storks] (https://www.env.go.jp/nature/choju/docs/docs5/itachi_kounotori.pdf)

Ecology

It works alone day and night. They mainly inhabit waterside areas such as rivers and lakes, and use their webbeds to swim well. I sometimes climb trees. When guarding the area, it stands on its hind legs and looks around. In addition to using holes and gaps as nests, they also like to enter holes other than nests. They mainly eat animals such as mice, birds, and amphibians.

Habitat

I found it on the riverside upstream of Asakawa. When I noticed it, I swam away and ran away for a few meters, then stood on two legs and stood on guard. If I didn't approach it, it wouldn't run away and I could observe it. After a while, it slipped through the cracks in the concrete blocks and ran away.