European mink (Mustela lutreola). A semi-aquatic mustelid that inhabits the banks of rivers and lakes in France, Romania, Spain, Russia, Ukraine, Estonia and other countries. Males have a body length of 37–43 cm, females 35–40 cm; body mass ranges from 450 to 800 g, showing sexual dimorphism. It primarily preys on small mammals, birds, amphibians, crustaceans, fish and insects, and hunts using its sense of smell. It is active at dawn and dusk, is solitary, and rests in burrows. Its population declined sharply after the 20th century; due to overhunting for fur, habitat destruction and competition from the introduced American mink, it has been classified as Critically Endangered (Category I A), and conservation measures are being advanced.