How Birds Sing: the Amazing Syrinx

Songbirdssongbird:a species from the oscine (ah-SEEN) group of passerine (PASS-er-een) birds, songbirds (including sparrows, thrushes, and warblers) have a specialized voice box called a syrinx that can produce complex sounds, songbirds must learn their songs rather than developing them instinctively have evolved a specialized two-sided vocal organ called the syrinxsyrinx:SEE-rinksthe bird voice box, located at the branch point between the trachea and bronchi and containing vibrating tissues called labia, in songbirds capable of making two sounds at once via independent muscle control that allows them to perform impressive feats of vocal gymnastics—including the unique ability to create two unrelated pitches at once.

Birds use a syrinx to produce sound

Here are some examples of how birds use their syrinx to produce impressive sounds.

More pitches than a piano

How does the Northern Cardinal (Cardinalis cardinalis) span a wider range of pitches than a piano in just a tenth of a second? Remarkably, the secret to the Northern Cardinal’s vocal prowess has been measured in the lab.1 It turns out that these vocal gymnastics are made possible by a seamless switch between sides of the syrinxsyrinx:SEE-rinksthe bird voice box, at the branch point between the trachea and bronchi and containing vibrating tissues called labia, in songbirds capable of making two sounds at once via independent muscle control partway through the cardinal’s most dramatically sweeping notes.

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Northern Cardinal photo by egdc211, song recording Macaulay Library, pink and green indicate opposite sides of the syrinx

 

Speedy trills

There’s more to the domestic Island Canary’s (Serinus canaria forma domestica) delicate song than meets the human ear. In the well-studied “A syllable” trilltrill: in birds, an uninterrupted note made of repeating elements produced at high speed, often at a stable pitch the male canary alternates between high and low notes by rapidly switching sides of the syrinxsyrinx:SEE-rinksthe bird voice box, at the branch point between the trachea and bronchi and containing vibrating tissues called labia, in songbirds capable of making two sounds at once via independent muscle control —all without taking a breath. Performing these trills well can pay off. Studies have shown that female canaries consistently prefer males who sing faster and with a wider range of pitches.2

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Domestic Canary by Gelber Kanarienvogel via Wikimedia Commons, recording and figure adapted with permission from Suthers et al., J Exp Biol, 2012, pink and green indicate opposite sides of the syrinx

 

Two notes at once

With over 1,000 song types, the Brown Thrasher (Toxostoma rufum) has one of the largest repertoiresrepertoire:the full range of sounds that an animal makes, each used in context to communicate specific messages in the bird world. As part of that incredible variety, the thrasher sometimes sings two sweeping tones at the same time—a feat made possible by its two-sided vocal organ. By controlling each side of the syrinxsyrinx:SEE-rinksthe bird voice box, at the branch point between the trachea and bronchi and containing vibrating tissues called labia, in songbirds capable of making two sounds at once via independent muscle control independently, thrashers create unique sounds that only a bird has the ability to produce.

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Brown Thrasher by Corey Hayes, song recording by Macaulay Library, pink and green indicate opposite sides of the syrinx

 

The ultimate trill

The Wood Thrush (Hylocichla mustelina) song ends with one of the most complex sounds a bird can create. Layered above a series of lower-pitch mini-trills is a series of higher-pitch sweeping tones. To perform this impressive trilltrill:in birds, an uninterrupted note made of repeating elements produced at high speed, often at a stable pitch the bird must pair impeccably timed breath control with independent muscle movements on each side of the syrinxsyrinx:SEE-rinksthe bird voice box, at the branch point between the trachea and bronchi and containing vibrating tissues called labia, in songbirds capable of making two sounds at once via independent muscle control .

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Wood Thrush by Corey Hayes, song recording by Macaulay Library, pink and green indicate opposite sides of the syrinx

 

Further Learning

Interactive: How Birds Sing

Animate the bird voice box and hear the impressive results.

Animate the Syrinx >

Animated Slides: Anatomy of Bird Song Slides

Animated scientific illustrations bring learning to life.

Download The Complete Set >