A male Amur tiger can way over 230 kilograms. It is believed to be the largest cat in the world, but up to now scientists that catch tigers for research have failed to catch an Amur tiger that is heavier than the largest male Bengal tigers caught for research in Nepal. Research by WCS (Wildlife Conservation Society) together with Russian scientists has shown that a female Amur tiger has a home range of up to 20 by 20 kilometres. Some males patrol an area as large as 40 by 40 kilometres. The home range of a male in his prime can include that of several females. As a result of these extensive territories it is clear that a very large area, about the size of Italy, is needed to support a viable population consisting of several hundred animals. Tiger territories can be relatively stable for several years, but they often shift during a tiger’s life. An animal may, for instance, may take over part of the range of a neighbour when it dies, or it may lose part of its territory to a new competitor. However, tigers do not migrate, even when a situation occurs when most ungulates move outside their territory, for instance to avoid a local thick snow cover. Adult male tigers are aggressive towards other males and they will not share their territory. It is not uncommon that males are killed during territorial fights and that's one reason why there are less adult male tigers than there are female tigers.

A tigress will also defend her territory against other adult females, but a sub-adult female will often take over part of her mother’s range when she becomes independent. Young males often cover long distances before they settle down and manage to secure a territory for themselves. This is a dangerous episode in their lives that many young males do not survive. A large number of subadult males are killed by other males and also a relatively large percentage of young males are killed by poachers.

Tiger Prey
The Amur tiger needs large prey to survive, like boar and red deer. There are even cases known of adult brown bears that were killed and eaten by Amur tigers. This probably only happens when these bears are surprised during hibernation in their den. However, brown bear cubs are killed more often (indicating that male tigers can drive away the defending mother bear) and the smaller Himalayan black bear is a very common ingredient on the Amur tiger’s menu.

It is very fortunate that in Russia, contrary to India, attacks on humans are very rare. In almost all of the very few known cases the tiger acted out of self-defence. Although humans don't have much to fear, the tiger isn't tolerated close to towns. When at the end of the eighties the supply of prey suddenly decreased because of poaching, tigers appeared very close to the suburbs of Vladivostok (killing a few stray dogs), large drives were held and several tigers were killed.