Wolves tend to kill mostly young, old, and debilitated animals, with most healthy ungulates (elk, moose, deer, bison, etc.) escaping their attacks.

By comparing the traits of wolf kills to those of animals killed for other reasons (e.g., hunters, vehicle collisions), researchers have shown that wolves primarily kill weaker animals, which comprise a small fraction of the total prey population. The conclusion from this research is that wolves are often unsuccessful in their hunting endeavors because most prey populations are dominated by individuals they cannot catch.

Prey isn’t always abundant, so wolves have a metabolism that helps them store fat and energy for long periods while prey is scarce. The most a large gray wolf can eat at one time is about 22 pounds, but an adult can go almost two weeks without food, making up the “famine” part of their diet.