Why Do Birds Call?

Birds are among the most vocal of all living things. Many bird calls are so melodious to human ears that they have found mention in our folk songs and literature.

Not all birds have sweet voices, though. Crows, pigeons and even the beautiful peacock come to our mind here. Their calls are so raucous and unmelodious that there would be few of us who would want to hear them.

Interestingly, there are also some birds that have no voice. For example, storks can only make sounds by clanking their bills. They have no apparatus to make a true call.

The question is why do most birds call? In nature nothing is without purpose. The calls of birds serve the same purpose as our own languages. We use language to communicate a variety of sentiments and information to other members of our species. The calls of birds also perform this function. A great many of bird calls have specific meaning to other members of the caller's species. Many birds use calls to mark their territory, to attract mates and to keep away or challenge rivals. Many birds such as babblers and crows that move in flocks use calls to keep in touch with other members of their flock and to signal the presence of food.

Some bird calls, such as alarm calls, communicate danger signals across species. Alarm calls are different from other calls in that they are recognized for what they are even by birds, and animals, of other species. For example, when a babbler or a sparrow sees a cat or a snake, it will begin sending out its specific alarm calls. This not only attracts other babblers or sparrows, but also a variety of birds ranging from mynas, crows, bulbuls and drongos who all add their own specific alarm calls to the general cacophony. Not only that, gathering courage from their numerical superiority, the birds will sometime attack and drive away the enemy from the area. Ornithologists describe this curious behaviour of birds as mobbing.

Interestingly, many birds such as drongos and mynas are excellent imitators of the calls of other birds, although what survival value this mimicry has for the mimicking birds is still not clear.

An innovative use of calls is to be found in the koel. As is well known, koels do not build nests and parasite on the nests of other birds, particularly crows. When the female koel is ready to lay eggs, the male and the female work to a plan to drive away the crows from their nest, so that the female koel could deposit her eggs in the crows' nest. First the male koel approaches the nest and starts calling loudly. Irritated by the presence of the intruder and the noise he is making, the crows attack him. The koel is a swifter flier than crows, but he keeps just out of the grasp of the enraged crows to lead them far away from the nest. In the meantime, the female approaches the unguarded nest and lays her eggs.

Although among humans we generally relate singing ability with the female sex, in birds, just the opposite is true. The most vocal and melodious singers are the male birds.