* Japanese name: Ezoshimarisu
* Scientific name: Tamias sibiricus lineatus

* Description: This is a rodent in the squirrel family, with light-brown fur and stripes of darker and lighter brown fur around the eyes and along the back. Body length is about 14 cm, tail 12 cm. It has large mouth pockets, which it crams full of food.

* Where to find them: The Siberian chipmunk is the only species of chipmunk in Asia, and in Japan it is native only to Hokkaido. But it is a popular pet, and many have escaped from homes in Honshu and further south, making sightings possible almost anywhere. Unlike many squirrels, this chipmunk lives on the ground, though it has no problem climbing trees using its long tail for balance. When it starts getting cold, sometimes as early as September, it prepares for winter and hibernation.

* Food: Nuts, acorns, seeds, fungi, insects. Food is hoarded in the underground burrow where the chipmunk spends the winter.

* Special features: Unlike lots of other rodents, the male Siberian chipmunk is smaller than the female. They are also unusual in that they court the female before copulation. Males follow females that are fertile, and fights over such females are common. After copulation, the male stays with the female for up to two hours.

This guarding behavior is probably to ensure that another male doesn’t come along and steal his female: It gives his sperm a chance to fertilize her eggs. The female might want other partners, however, and so chases the male away after he has hung around for a couple of hours. Females give birth to three to seven babies at a time. There is a documented case of a female producing a litter fathered by her 7-month-old son . . . Some males should be chased away from the beginning.