The Amur, or Siberian, tiger (Panthera tigris altaica) is the largest big cat in the world, weighing up to 300 kilograms (660 pounds). Unlike the other tiger subspecies, which are jungle-dwellers, the Amur tiger lives in the birch forests of Russia's frigid and snowy Far East, and formerly inhabited the colder regions of China and Korea. In fact, the animal thrives in winter temperatures that often drop to -50 degrees fahrenheit (-45 celsius). Due to relentless hunting, Russia's tiger population had dropped to around 40 individuals by the 1930′s. Since then, the animal has been protected, and its numbers have rebounded to around 500. However, it is still threatened by illegal hunting and habitat loss in the form of logging and development.