Papua New Guinea is an island country. It lies in the Pacific Ocean. Deep in its rainforests, male birds-of-paradise gather. Their colorful feathers shine in the morning sun. From the trees, they make a sharp, repetitive cry. They are calling out to female birds-of-paradise. When one appears, the males are ready to perform. They dance and hop about. They spread out their feathers, trying to get the female to notice them.

Birds-of-paradise are well known for their showy mating habits. These habits are pretty unusual. The male has to work really hard to get a mate. His approach involves strutting and dancing.

There Are no Random Dance Moves

One example is the male Superb bird-of-paradise. He totally changes what he looks like to get noticed. First, he fans out his black tail feathers. A few bright-blue feathers stick out. It makes him look a crazed smiley face. Then he starts dancing around. He clicks and snaps his tail, flashing his bright-blue shimmery feathers.

The male's dance moves may seem random, but they are carefully planned. He is trying to win over a female. He keeps trying until she is interested. Female birds-of-paradise have all the power. They get to pick their mate.

Colorful Feathers Help Attract a Mate

Other male birds-of-paradise show off their colorful feathers. The ribbon-tailed Astrapia is one example. It has bright white tail feathers. They stretch one meter (three feet) long. Such long feathers help the male Astrapia attract a mate. Still, they aren't exactly useful for survival. So why do these birds have long feathers at all?

Charles Darwin was a naturalist who studied animals and plants. He proposed the now-famous theory of natural selection. Natural selection is sometimes called "survival of the fittest." It means that animals with traits that help them survive will live on. A trait might be its color. It might be what they eat or how they hunt. If an animal lives long enough, its children can also have traits that help them survive. Animals without these traits might get eaten or die out.

Yet the Astrapia's long tail feathers do not seem to offer a survival advantage. The feathers might even put the bird in danger. A predator could spot it more easily.

Female Birds Shape Their Mates

Darwin had another idea to account for this. He called it the theory of sexual selection. Darwin suggested that some traits help improve an individual's chances of attracting more or preferred mates.

Male birds-of-paradise have evolved to better attract mates. The females directed the changes. Say a male is born with longer-than-average feathers. For whatever reason, a female likes long feathers more than short feathers. So, she mates with him. Their offspring have both of their parents' features. They have their father's long feathers. They also have their mother's fondness for long feathers. Over generations of birds, these traits become more common. More males are born with longer feathers. More females are born that prefer longer feathers. Over time, the female has shaped the male to her liking.

Male birds-of-paradise are very fun to watch. They love to dance and be center stage. Their show is for the ladies. After all, females are the ones who shaped the male's beautiful look. They are also why the males behave in a way that looks silly to us.