Even non-birders can appreciate the delicate tones and melodious tunes of birdsong, but it is more than just music to birds. Understanding why birds sing can help birders learn different cycles of a bird's life and how to best listen to birds at different times of the year, including how to identify birds by voice and sound.
About Bird Songs
A bird's song is only one type of sound birds make, but it is the most recognizable. Birds have very complex vocalizations, often with more than one tone produced simultaneously, thanks to the specialized syrinx (their equivalent of a voice box) that allows them to create independent sounds in different parts of their trachea. Songs may last 2-10 seconds or more, and are often repeated in long sequences. A song is generally more musical than other calls, and often incorporates a range of pitches and rhythms into one connected sequence. In many bird species, only male birds sing, and they do so conspicuously from high, exposed perches in order to attract attention to their song and for the song to be broadcast over greater distances.
A Reason to Sing
Birds use songs for a variety of purposes depending on the season and each individual bird's needs. The most common reasons for birds to sing include:
- Claiming and Defending Territory
A loud, complex song advertises to nearby birds that the territory is already inhabited by a healthy, active male. Any bird that wants to challenge him for his territory can judge their chances of success by interpreting the strength and complexity of his song.
- Attracting a Mate
Just as a male's song advertises his territorial boundaries to rivals, it also lets nearby females know that he is strong and able to defend a good region. The complexity of a song can indicate health and age, since older birds have more time to learn new tones and tunes, and the amount of time a male spends singing demonstrates his endurance. This lets a potential mate know that he can provide for her and give her the best chance of raising healthy chicks.
- Courtship Duets
In the courtship rituals of some bird species, both genders will sing in a complex duet that strengthens their pair bond. The interplay of their songs and how they respond to one another demonstrates their responsiveness and reinforces their commitment to one another. This also helps advertise that they are unavailable to other single birds.
- General Communication
While birds have a variety of calls that are used for different types of communication, song can also be used for more general purposes. A simple, basic song might call a mate to a new food source or summon them to incubation duty, or might keep birds in touch while flying.
While some bird species sing year-round, most songs are sung from late winter to early summer. This is exactly the time when birds mate and therefore need to claim territories, attract mates, and strengthen pair bonds, and songs are an important part of the process. The birds that do sing year-round are less likely to be migratory and therefore still defend their territory and often remain with the same mate throughout the year, increasing their need for year-round songs.
The Joy of Song
Some ornithologists have theorized that birds may also sing simply for the pleasure of it. While more research is needed as the idea of bird emotions is still not understood well and can be controversial, it is possible that birds enjoy their own songs and singing with other responsive birds nearby. In cases when birds sing without territorial or courtship concerns, the beauty of the song and the enjoyment of producing it may well be the reason why they vocalize.
Practice Makes Perfect
Just as babies aren't born with a full vocabulary, birds aren't hatched with the ability to sing. Young birds first practice begging calls and other attention-getting tones in the nest, but gradually learn to sing by listening to the songs of their parents. Because of this education, birds in different geographic areas will learn slightly different songs. In different environments, birds even learn to mimic other bird species or non-bird sounds. Birds in the Mimidae family, the mimic thrushes which include the northern mockingbird, even incorporate mechanical sounds such as car honks, cell phones, and construction equipment into their songs.
Dangers of Singing
Singing is not without its dangers. It takes great energy and many calories to produce loud, clear tones, and the sounds can easily attract predators and make the singer more vulnerable. But the benefits birds get from singing, including a prime territory, a healthy mate, and a place to raise their young, are well worth the risk. Birders also benefit, not just from identifying species by their song, but simply enjoying the song that greets them whenever they pull out their binoculars.