Wolves are carnivores, or meat eaters. Gray wolves prey primarily on ungulates – large, hoofed mammals such as white-tailed deer, mule deer, moose, elk, caribou, bison, Dall sheep, musk oxen, and mountain goats. Medium-sized mammals, such as beaver and snowshoe hares, can be an important secondary food source. Occasionally wolves will prey on birds or small mammals such as mice and voles, but these are supplementary to their requirements for large amounts of meat. Wolves have been observed catching fish in places like Alaska and western Canada. They will also kill and eat domestic livestock such as cattle and sheep, and they will consume carrion if no fresh meat is available. Some wolves eat small amounts of fruit, although this is not a significant part of their diet. If prey is abundant, wolves may not consume an entire carcass, or they may leave entire carcasses without eating. This is called “surplus killing” and seems inconsistent with the wolves’ habit of killing because they are hungry. Surplus killing seems to occur when prey are vulnerable and easy to catch – in winter, for instance, when there is deep snow. Since wolves are programmed to kill when possible, they may simply be taking advantage of unusual situations when wild prey are relatively easy to catch They may return later to feed on an unconsumed carcass, or they may leave it to a host of scavengers. Additionally, they may cache food and dig it up at a later time. Red wolves primarily prey on white-tailed deer, raccoons, rabbits, nutria and other rodents.
狼是食肉动物,或肉食动物。灰狼主要捕食有蹄类动物——大型有蹄哺乳动物,如白尾鹿、骡鹿、驼鹿、麋鹿、驯鹿、野牛、达尔羊、麝牛和山山羊。中等大小的哺乳动物,如海狸和雪鞋兔,可以是重要的第二食物来源。狼偶尔会捕食鸟类或小型哺乳动物,如老鼠和田鼠,但这是对它们大量肉食的补充。在阿拉斯加和加拿大西部,人们观察到狼在捕鱼。他们还会宰杀和食用牛羊等家畜,如果没有新鲜的肉,他们会吃腐肉。有些狼吃少量的水果,尽管这不是它们饮食的重要组成部分。如果猎物丰富,狼就不能吃掉一整具尸体,或者离开整具尸体而不进食。这被称为“多余的杀戮”,似乎不符合狼因为饥饿而杀人的习惯。过度捕杀似乎发生在猎物易受攻击和容易捕获的时候,比如在冬天,当有很深的雪的时候。因为狼的程序是在可能的情况下杀人,它们可能只是利用一些不寻常的情况,当野生猎物相对容易捕获时,它们可能会返回来以未消耗的尸体为食,或者它们可能会将其留给一大群食腐动物。此外,他们可能会把食物藏起来,以后再挖出来。红狼主要捕食白尾鹿、浣熊、兔子、海狸鼠和其他啮齿动物。