On February 10, 2015, I was getting ready to leave Yasugawa in mid-afternoon when a nutria came very close and stopped to eat.
In the summer of 2013 I saw a nutria in the wild for the first time along the north bank of Yasugawa, the river that flows near my neighbor on its way to Lake Biwa.
Recently I’ve seen a nutria several times in the same place along the southwest bank. It lives under a clump of bushes that overhang the river near the golf putting course in Deba, Ritto City, Shiga Prefecture (滋賀県栗東市出庭11).
Nutria are an invasive species in Japan. They have been spreading throughout western Japan since around the end of World War II. Apparently, they are becoming quite a nuisance as they eat farmers’ crops. The Lake Biwa Museum website has a section on invasive (“alien”) species, 外来生物 (gairaiseibutsu) in Japanese. The section include an English page about Nutria. The information there is a bit general and outdated. If you read Japanese, see ヌートリア.
Some prefectures and municipalities in Western Japan are concerned about invasive species and protecting native plants and animals in the natural environment. For example, Shiga Prefecture has a website (in Japanese), 滋賀県 – 自然環境保全課.