Siberian chipmunk  The Siberian chipmunk or common chipmunk ("Eutamias sibiricus") appears across northern Asia from central Russia to China, Korea, and Hokkaidō in northern Japan. Imported from South Korea and introduced in Europe as a pet in the 1960s, it is the only chipmunk found outside North America and is classed either as the only living member of the genus "Eutamias", or as a member of a genus including all chipmunks. Although these animals can exhibit slight variations in coloration in different geographic regions, they possess several common characteristics. Typically the Siberian chipmunk has 4 white stripes and 5 dark stripes along the back. It is 18–25 cm long, a third of which is the tail. The weight of adults depends on the time of year and food availability. Even though the Siberian chipmunk normally grows to 50–150 grams, this species is relatively small compared to other Sciuridae, such as the red squirrel. The Siberian chipmunks are not known to exhibit sexual dimorphism, and size and body proportions are the only way to distinguish younger chipmunks from older ones. Their small size may contribute to their relatively short lives, which tend to range from 2 to 5 years in the wild. However, when placed in captivity, as seen in Europe in the 1960s, they have the potential to live anywhere from 6 to 10 years. Siberian chipmunks were found only in their native range of Eastern Asia until the 1960s, when this species was introduced to European countries. During the 1960s, South Korea began to export these animals to Europe as a part of the pet trade. Between 1960 and 1980, South Korea exported more than 200,000 individuals to Europe. Human introduction is a major risk for the spread of this species into other forests and areas. By the 1970s, the Siberian chipmunk inhabited suburban forests and urban parks in Belgium, France, Switzerland, Germany, Italy, the Netherlands, and Austria. This is mostly caused by owners releasing these animals because they no longer wanted them as pets, or the owners purposefully freed the chipmunks to live naturally in the wild. Other Siberian chipmunks escaped from captivity and inhabited the forested areas of Europe. The Dutch chipmunks for example are escapees from a former zoo in Tilburg. When the zoo was shut down and all animals were moved away, many chipmunks got forgotten due to their underground residence.