Why do birds sing

introduction

Surely many of us and on many occasions have asked ourselves the following question, why do birds sing?

It is said that if human beings had the same power-size ratio as a Common Wren (Troglodytes troglodytes), you could hear us more than 150 kilometers away, considering that after wrens it is the smallest bird in Europe. It weighs less than 10 grams. Birdsong is the pure image of effort.

We have to bear in mind that birds have a different system from that of human beings not only in the way they produce sound but also in the way they hear it.

Continuing with the wrench, admired for his ability to sing, a study was done taking a phrase of about 8 seconds and “stretched” it to 65 seconds, discovering that it contains an astounding 103 notes, most of which we don't even hear, but they contribute to the final effect.

Every spring there is an explosion of songs in nature with an incredible wealth of variety of sounds that delight our ears.

Oddly enough, for many people, they go unnoticed. Most human beings live with their backs to nature, but in spring, when the windows of our house are open and the garden is singing a Blackbird, a Robin, a wrench or a Warruca capirotada Do we appreciate this virtuosity?

But... why do birds sing?

It is not known for certain why birds sing, but there are two main theories:

1. To defend their territory

For 4 months of every year, every time we leave the house we hear birds singing, but that display qualities, that waste of fantasy, what more unlikely modulations, what extravagance and partly to defend their territory.

The male must be “recognizable” to others of his species as he builds his territory and if he can increase his fief, distinguishing him at all times from that of his neighbor. At the same time, he has to control them so that they don't invade his own, while he invades someone else's. All these territorial tasks require not only the development of songs that are recognizable by individuals of the species, but also a sense of demonstrating that it is stronger. This is why territorial songs tend to be very pure to our ears and aimed at showing the individual where he is.

An alarm, on the other hand, is usually a very dissonant sound that reaches your ear and doesn't tell you where the author is, because he wants to warn his relatives of the danger, but without being discovered.

2. To attract the female

With a few exceptions, males sing. The less developed sounds that the two sexes make to maintain contact and other everyday needs are usually called “complaints”, although this is a distinction that could be nuanced, but one that we can stick with.

Let's not forget that the complexity we hear, however amazing, is a part of what is there. The intention is apparently clear: the male “offers” himself to the female who chooses.

Field studies have shown that females are extremely demanding, they don't miss a single detail and if the male fails he loses his chance. The female is looking for, or listening to, another candidate.

In itself, the amount of singing already speaks of the tremendous effort involved, first of all physical, the more you sing the louder you are.

And entering into quality, a male has to defend his territory and attract a partner, which means having to earn territory or if he can, increase.

You need to know if another bird singing nearby is of the same species and therefore a competitor, and if it is outside or inside your territory.

He has to convince the female that the territory is good for producing offspring and spreading his genes while assuring his partner incubating in the nest that he will guard everything to go well.

The development of the complexity of singing makes the male recognizable and distinguishes between the specific and generic identity of other individuals.

Apart from these theories, we are left wondering if birds' songs are also part of pleasure and enjoyment in and of themselves.

Francisco Serrano, Biodiversity