与其他动物相比,鸟类的活动空间更为广阔,它们有的能翱翔于天际,有的能在大海畅游,还有的可以在陆地上健步如飞。凭借着“速度”这个法宝,它们在各自的生活空间里悠然自得。尖尾雨燕是世界上飞得最快的鸟,它们体形修长,在空中飞行时,就像离弦的箭一样快,剪刀形状的尾巴则可以帮助它们避开空气阻力。更为奇特的是,尖尾雨燕的尾部还长有脊骨,这非常有利于它们在天空滑翔。它们的平均速度为每小时170千米,最快时每小时 Compared with other animals, birds have broader space for activity. Some of them can fly in the sky, some can swim in the sea, and others can walk on land. With the magic of speed, they are indulgent in their own living space. The tip-swirling birds are the fastest flying birds in the world. They are slender in shape and fly as fast as off-center arrows. Scissor-shaped tails help them avoid air resistance. Even more peculiar is the tail of the swift tail has long spine, which is very conducive to their gliding in the sky. Their average speed is 170 kilometers an hour, the fastest hour