Why Do Birds Sing?

By Antonia Čirjak on January 23 2020 in Did You Know

Bokmakierie bird calling - Telophorus zeylonus - South Africa
Bokmakierie bird calling - Telophorus zeylonus - South Africa

What is a bird song? Apart from the melodic and lengthy performances which come to mind first, there is also a wide range of vocalizations that birds employ for many different purposes. 

As a group of creatures that can sometimes move across long distances very fast and can be scattered on vast territories, birds cannot always rely on the appearance or chemical signals in their communication. Still, they have all the same needs as other groups of animals: finding partners, raising young, surviving predators, locating food sources, maintaining social functions. So birds evolved to rely on the way of communicating that does not necessarily require proximity or being in the line of sight: sound. Bird’s vocalization is, in a way, a language. 

A Huge Sounds Repertoire

Each species has a distinct range of vocalizations, with each specific sound used for its own purpose or circumstance. From tweets, chirps, shrills, various clicking, buzzing noises, whistling, holding notes to creating unique and complex melodic structures and incorporating imitations of other sounds. 

For birdwatchers or scientists, learning to identify species by its voice and also decode its signals can be crucial to gaining insight into their behaviors and ecology.

How Can Birds Make Such A Wide Variety Of Sounds? 

Robin (Erithacus rubecula).
Robin (Erithacus rubecula)

Birds do not have vocal folds similar to mammals. Instead, they produce calls, songs, and melodies thanks to a complex vocal organ located at the base of a bird's trachea. This organ is called the syrinx. The sound is produced through the interaction of the vibrations of the syrinx walls and the airflow through the system of membranes. Its specific structure, size, and location are different for each species, and this difference gives each one its distinguishable voice. Neck, beak, and sometimes unique features also play a role in shaping the resulting sounds.

The Contact Calls

Contact calls are the broadest category: these are short, sharp, and frequent vocalizations social species of birds exchange with each other to stay in touch while they hunt or gather materials. Birds that rely on cooperation in their search for food would often use a select signal to recall the remainder of the group to a source they identify. Parents use whistles or chirps to keep in touch with their semi-independent young.

The Warning Calls

Sharp, loud, penetrating sounds are a great survival strategy employed by both social and solitary birds. The group can feed safely if each member would warn others about a potential threat. Predators have less success in hunting if their movement is exposed by the birds signaling everyone around. Even mammals (like deer) that depend on their flight response for survival learned to rely on the birds’ warning. Predatory birds often use shrilling penetrating cries as part of their attack or the birds who actively protect their nest from a threat. Territorial birds often produce long, elaborate songs at dawn to claim their territory and social status.

The Cries For Help Or Provision

Three birds singing.
Three birds singing.

The best example would be the young birds’ behavior. Most of the time, chicks in the nest remain silent while the parent is away; but as soon as their mother or father returns, they use their high pitch, excited chirping to signal their carer that they need to be fed. Birds that regurgitate food for their young rely on that signal and touching of the beaks as a regurgitation trigger. Fledglings that have left the nest but still follow their parents around (for example, blackbirds or starlings) often chase after their mothers, chirping and crying non-stop.

The Mid-Flight Calls

Birds have distinct types of calls only used midflight; typically, these are short and easily identifiable. They are typically announcements of the passage of migrating flocks. These sounds are essential for keeping flocks together, especially in low visibility (rain, fog, or night flights). Interestingly, the use of calls at night has been associated with more collisions with buildings; it is still poorly understood, but some scientists suggest that artificial materials can reflect sounds and confuse sensitive birds.

Courting Calls

Different bird species rely on many different strategies to procreate. Some of the most elaborate and distinct songs are associated with courtship and competition for mating partners. Even birds that mate for life, like Japanese cranes, and, theoretically, do not need to compete, can perform stunning dancing and singing rituals with their mates.

Two Japanese cranes with red crowns are involved in a mating dance ritual.
Two Japanese cranes with red crowns are involved in a mating dance ritual.

When finding a partner is not guaranteed, and your partners are spread across distances (or you live in a lush forest with low visibility), calling the partner to you or following their voice might be your only choice. The power of the mating call during the appropriate season can be irresistible, and some hunters know it well, using a calling female or imitating the sound with distinctive whistles.

How You Can Learn To Recognize Birds By Their Song

These days, there are many great “birdsong libraries”; recordings, websites, and apps that provide samples for comparison. However, it is most helpful to narrow down your search first. Start by learning what birds inhabit your area, how common they are, what type of the habitat they prefer (for example, undergrowth, hedges, or canopy), what are their feeding habits (on the ground or mid-flight), whether they live in groups, and what stage of their life cycle it is right now. After you narrowed down your search, you can listen to the samples and learn what they mean; and then you can easily identify a bird you cannot see and “translate” their language.

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