" Vulnerability--not hunger, not anger, and certainly not spite--is the key to predator-prey relationships. The skill and viciousness of the hunter matters less than the size, speed, strength, health, and ferocity of the hunted. Vulnerability explains why large predators tend to kill the old, young, and sick members of prey populations. Predators eat the mild and weak because those are the animals they can catch and kill. "

― , Vicious: Wolves and Men in America