新托福听写训练 第9期（在线收听）

For the next couple of weeks, we will be focusing on how animals communicate with each other.Up to now, we've had a rather narrow view of vocal warnings that animals give each other. Some recent research indicates that this communication is a lot more complex than we've traditionally thought. Let me give you an example, Take prairie dog, of course they are not really dogs at all but wild rodents who live on the plains in the western part of United States. In case you can't visualize them, let me describe them to you. They're about as big as squirrels but without the bushy tail, and unlike squirrels, they live in holes whole in the ground, and they spend a lot of time just outside their holes because they have a lot of enemies: hawks, coyote, human, you name it. When they spot a potential threat, they bark to warn one their neighbors and then they escape down into their holes. big deal you say, well, it turns out they can differentiate among predators. Researchers have discovered that the bark differs for different predators. Coyote warnings are different from people warning, for instance. But it goes deeper than that, there's actually evidences that their barks differentiate between individual predator of same species. The researchers found for example, the prairie dogs had a different bark for each member of the research team.