8 Animals in Groups-High

Animals in Groups FOCUS Question How does living in a group help vertebrates survive?

群居动物焦点问题群居生活如何帮助脊椎动物生存?

Animal Groups A group of vervet monkeys are feeding in a grassy area when they hear a low grunt. They quickly look up and run to the nearest bush. The grunt came from another vervet warning them that an eagle was nearby. Living in a group, or being social, helps many vertebrate species survive. A group may eat, sleep, move, and nest together all year long or for just part of the year. A group may have a few members or millions. Not all vertebrates live in groups. But for those that do, being social has powerful benefits. Wowser! Vervet monkeys have different warning calls for different predators.

动物群体一群长尾猴正在草地上觅食，这时它们听到一声低沉的咕噜声。 他们迅速抬起头，跑向最近的灌木丛。 咕噜声来自另一只长尾草，警告他们附近有只鹰。 群居或群居有助于许多脊椎动物的生存。 一个群体可能全年都在一起吃饭、睡觉、移动和筑巢，或者只是一年中部分时间在一起。 一个群体可能有几个成员，也可能有数百万成员。 并非所有的脊椎动物都是群居的。 但对于那些有社交能力的人来说，社交有巨大的好处。 老古板!长尾猴对不同的捕食者有不同的警告叫声。

Dinnertime! Being social can make it easier to get food. Some species use cooperative hunting. For example, Harris's hawks team up to hunt rabbits and other animals. During a hunt, each hawk does something different. One bird may spot the prey while another forces it out of bushes. One hawk may block an escape route while another catches the prey. In an elephant family, the leader is an older female. She is called the matriarch. She can remember many places where the plants they eat grow. When food becomes hard to find in one place, she leads her group to another place.

晚餐时间!社交可以让它更容易获得食物。 有些物种采用合作狩猎。 例如，哈里斯的鹰会组队捕食兔子和其他动物。 在捕猎过程中，每只鹰都会做一些不同的事情。 一只鸟可能会发现猎物，而另一只鸟则会把猎物赶出灌木丛。 一只鹰可能会堵住逃跑路线，而另一只则会抓住猎物。 在象族中，首领是一只年长的母象。 她被称为女家长。 她能记住许多它们吃的植物生长的地方。 当一个地方很难找到食物时，她会带领她的团队去另一个地方。

Better Safe Than Sorry Living in a group can protect members from predators. Zebras live in large herds. With many animals watching for danger, it's easier to stay safe. And since each zebra can spend less time watching, it has more time to eat. Moving as a group can help animals stay alive by confusing their predators. Minnows are fish that swim in large schools. Fish that hunt them have a hard time picking a single minnow to chase. If a predator gets close, the school may split into two groups or quickly swim in all directions.

生活在一个群体中可以保护成员免受捕食者的伤害。 斑马群居。 有很多动物在监视危险，所以更容易保持安全。 因为每只斑马可以花更少的时间观察，所以它有更多的时间吃东西。 集体移动可以通过迷惑捕食者来帮助动物生存。 鲦鱼是成群游动的鱼。 捕食它们的鱼很难挑选一条鲦鱼来追逐。 如果捕食者靠近，鱼群可能会分裂成两群或迅速向四面八方游去。

Meerkats live in groups of up to fifty (see cover). They stay safe in underground burrows. But some must leave their burrow each day to find food. Group members take turns watching for predators when the group is out. If the guard, or sentinel, spots danger, it barks to warn the others. Group behavior also helps animals protect their young. Crows bother and even attack birds of prey that hunt young birds. This behavior is called mobbing. Musk oxen stand in a close circle facing out if a wolf pack is near. The calves stay inside the circle.

猫鼬以多达五十只的群体生活(见封面)。 它们安全地呆在地下洞穴里。 但有些必须每天离开洞穴去寻找食物。 当小组成员外出时，小组成员轮流监视捕食者。 如果哨兵发现了危险，它就会吠叫来警告其他动物。 群体行为也有助于动物保护幼崽。 乌鸦骚扰甚至攻击捕食幼鸟的猛禽。 这种行为被称为围攻。 如果狼群靠近，麝牛就会站成一个紧密的圆圈，朝外。 小牛犊留在圈内。

Move as a Team Traveling in a group makes it easier for some vertebrates to get where they're going. When geese fly in a V-formation, they fly just behind and to the side of the bird ahead of them. They also beat their wings in time with the bird in front. This way of flying lowers the wind resistance— the force acting against the geese as they fly. As a result, the birds use less energy. They can fly for a long time before needing to rest. Science in Your World During bike races, riders often line up to lower wind resistance and save energy. Like geese, they take turns leading.

组队旅行对一些脊椎动物来说更容易到达目的地。 当大雁以v字队形飞行时，它们会飞到前面的鸟的后面和旁边。 它们也随着前面的鸟拍动翅膀。 这种飞行方式降低了风的阻力，即在雁飞行时作用于它们的力。 因此，鸟类消耗的能量更少。 它们可以飞很长时间才需要休息。 在自行车比赛中，骑手们通常会排队以降低风阻并节省能源。 像大雁一样，他们轮流领路。