http://www.answers.com/topic/amur-tiger
The brown bear is the only serious competitor of the Amur tiger, which sometimes tries to dispute tiger's kills,
especially in spring time when the bear gets out of its den and start looking for food.
According to various sources, the bear is usually the victor in such battles, unless the tiger ambushes the bear,
otherwise, the tiger usually retreats and does not engage in a fight with much stronger and bigger opponents
要約
１．ヒグマはアムールトラの唯一の競争相手である。
２．ヒグマは冬眠明けの春先にトラから獲物を奪いに行く。
３．多くの情報によるとこのようなケースで大抵の場合ヒグマが勝つ。
４．トラが待ち伏せをした場合は別だが、基本的にトラは自分より強くて大きい相手には戦いを挑まない