How Herding Can Provide Safety
In open grasslands there is no place for a large animal to hide. Thus a watchful grazing animal will see the slight movement that betrays the presence of a predator long before it is close enough to launch an attack. It sounds as though the hunters (predators) stand no chance at all. Unfortunately for the grazers, life is not so simple, however. A grazing animal must lower its head and look at the ground to feed. Its attention may be occupied for only a few seconds before it raises its head and resumes its watch while chewing the food it took, but hunters are patient and skillful and are concentrating intensely. Those few seconds provide time enough to advance a few steps and then freeze, body flattened against the ground. It may take hours, but eventually these repeated small advances will put the hunter within range—close enough to outrun its prey—and the long time the hunt has taken will have been worthwhile, because the resulting feast will be highly nutritious.
Clearly the grazers are at a disadvantage, because while they eat they are vulnerable to attack. The hunters also have a weakness, however, and it is one that allows the grazers to survive. Hunters can attack only one prey animal at a time. This applies even to the predators that hunt as a team, such as lionesses, wolves, and hunting dogs. Their hunt involves running down or ambushing an individual. Teamwork allows them to hunt animals much bigger and stronger than themselves and to hunt more successfully, but it does not allow them to attack more than one individual at a time.
完整版题目和答案请付费后查阅：
