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The Oldest Music
Scientists are only beginning to make sense of birdsong. A new book sheds light on one of nature's enduring mysteries.

The sonograms and sounds on this page are brief samples taken from The Singing Life of Birds: The Art and Science of Listening to Birdsong, by Donald Kroodsma, to be published by Houghton Mifflin Co., April 2005. The book consists of 30 stories about common birds, each story richly illustrated with sonograms and sound tracks on the accompanying compact disc.

How to Read a Sonogram

The elements of a sonogram are pretty simple and straightforward. The horizontal axis is time, and the sonogram is read from left to right, just as one would expect. On the vertical axis is frequency. A typical scale runs from 0 to 8,000 cycles per second, with “cycles per second” being the number of times per second that air compresses and rarefies to produce the sound we hear. Keep in mind that at middle A on a piano, the wire vibrates at 440 cycles per second, and the highest note on a piano is a C, at 4,186 cycles per second, which is about the opening note in the first black-capped chickadee sonogram below. The sonogram is, in essence, a musical score for birdsong. (Note: In the vertical axis on the sonograms, “cycles per second” is shortened to “hertz,” named after a German physicist, and a thousand cycles per second is a kilohertz, or simply kHz. The highest note on a piano is thus about 4 kHz.)

On the sonogram, different sounds have a predictable appearance. A slammed door or a gunshot is a “noisy” sound, consisting of a complex sound spanning many frequencies, and on a sonogram this sound is a brief, vertical mark spanning several thousand cycles per second. A woodpecker drum thus consists of a series of “slamming doors,” with the bill slamming into the tree numerous times in succession, and along the sonogram’s time axis one sees many vertical marks spaced out accordingly. A pure whistle held at 4,000 cycles per second would be a horizontal line on the sonogram, much like the opening whistle of the black-capped chickadee song in the first sonogram below. Slur the whistle down the scale, and the marking on the sonogram slides down, too, as seen in the last four notes of the first towhee song.

One begins to see the possibilities-it’s that simple. In the following examples, look at the sonograms as you listen to them, and you’ll soon hear a whole new world of birdsong.

Listed below are the .wav files for the collection of birdsongs from the article "The Sound of Music" To save .wav files to your computer, right-click on the link and choose "save target as" (PC) " or save link as" (Mac).

Black-Capped Chickadee, North American "hey-sweetie" songs.

Wav file: Chickadee--North America (size 586kb)

Songs of most black-capped chickadees across North America are the hey-sweetie, consisting of two main whistles, the first higher than the second; a slight pause occurs in the middle of the lower whistle, hence the two-syllable sweetie. A male sings many renditions of this hey-sweetie song on one frequency before shifting to another.

In the two sonograms, see that the first song is slightly higher in frequency than the second. Listen to these two songs, as the recording catches a male in the act of switching from a higher frequency to a lower one. As you listen, hear the hey and sweetie within each song, and hear how the pitch shifts to a lower hey-sweetie in the second song.

Black-Capped Chickadee, Martha's Vineyard "sweetie-hey" songs.

Wav file:Chickadee--Martha's Vineyard (size 526kb)

On Martha's Vineyard, the songs of the black-capped chickadee are different from those throughout North America. The songs on the Vineyard still consist of two main whistles, but both are on the same frequency. On the island are three different song dialects, the dialect on the western end of the island, at Gay Head, consisting of sweetie-hey songs, with the brief pause now in the first whistle, not the second.

At dawn, males alternate a low and a high version of this sweetie-hey song. In the sonagrams, see how the first sweetie-hey is lower than the second. As you listen to the songs, hear each element within the songs and how the male sings the second song at a higher pitch than the first.

Eastern Towhee, New England

Wav file : Towhee Song A (size 212kb)

Wav file : Towhee Song B (size 223kb)

Wav file : Towhee Song C (size 250kb)

Male eastern towhees in New England have several different songs in their repertoire, the three sonograms illustrated here all being from the song repertoire of one male. Each song is of the format drink-your-teeeeeee, with a couple of introductory notes (drink your) and then a series of repeated elements at the end of the song (teeeeeee).

As a male sings, he typically repeats one of his songs many times before switching to the next (unless you catch him in an energized dawn performance, when successive songs are usually different). With a little practice, each of the songs can be recognized by ear, and the switch from a series of one song to a series of the next is rather striking.

Bewick's Wren, adult song

Wav file: Bewick's Wren adult (size 526kb)

Each male Bewick's wren has a song repertoire of 15 to 20 different songs. In this particular song, see several introductory notes at the beginning and then two series of repeated elements at the end. The buzzy chatter (numbered “2”) followed by the four “S-shaped” notes (“3”) at the end of the song make this particular song distinctive. A male will repeat a song like this up to 50 times in a row before switching to another song in his repertoire.

Bewick's Wren, juvenile song

Wav file: Bewick's Wren babbling (size 455kb)

A young wren, like most other songbirds, must learn his songs much like baby humans need to learn their language from adults. These sonograms show how this young wren is "babbling" as he utters a nonsensical stream of sounds much like a human child does when learning to speak. (The CD for The Singing Life of Birds provides a more extensive comparison of wren and child babbling.)

Compare, for example, the elements numbered "3" and "2" in this brief sequence for this young male and for the adult male (see above). This young male is practicing these two elements, and they will eventually match perfectly the songs of adults around him. As he practices, however, see how uncertain he is in successive attempts at the same sound (look at those two S-shaped notes), so different from the crystal clear, precisely repeated elements of the adult. See also how this young male has elements 2 and 3 reversed, but he'll eventually reverse the order, singing all of the elements in the same order as the adults around him.

Song Sparrow

Wav file : Song Sparrow Song A (size 606kb)

Wav file: Song Sparrow Song B (size 559kb)

The particular song sparrow that was studied for The Singing Life of Birds had eight different songs in his repertoire. Illustrated here are sonograms of just two of those songs. See how Song A begins with three raspy notes, followed by an extended, broad-band buzzy note, then a series of repeated elements dominated by five low-frequency whistles, and finally a soft, low buzz on the end. Song G is strikingly different, as seen in the sonogram and heard when listening to these two songs.

With a little practice, all eight songs of a particular male can be easily recognized. One can then listen as a male repeats a particular song many times, eventually switching to another of the songs in his repertoire.

Eastern Winter Wren

Wav file : Eastern Winter Wren (size 665kb)

The song of the eastern winter wren is extraordinarily complex, consisting of well over 100 tiny notes that this male has learned from other singing males in his neighborhood. See all of the dainty little elements sprinkled about the sonogram, this particular song easily distinguished from the other song in this male's repertoire by the placement of the "high" and "low" series of repeated elements. As you listen, realize that the wren must hear the details of this song much better than we do or else he wouldn't be able to imitate the precise details of the neighbors' songs. Listen to this song at 1/6 th normal speed (on the CD that comes with The Singing Life of Birds ) and you begin to appreciate how the wren might hear this song.

Even more complex is the song of the western winter wren. Western males have much larger song repertoires, and each song is far more complex. These differences in singing between eastern and western winter wrens reveal that they are really two different species (illustrated in sonograms and sounds in the book).

Eastern Wood-Pewee

Wav file: Eastern Wood-pewee (size 792kb)

The songs of the eastern wood-pewee, like the songs of other flycatchers, are inborn, not learned as they are in songbirds like the chickadees, towhees, wrens, sparrows, thrushes, and the like. At dawn, the pewee uses three different songs, the pee-ah-wee, the wee-ooo, and the ah-di-dee, in fascinating sequences. Learn to recognize these three songs, and then find a pewee at dawn as he tells all that is on his mind. Hear him during a more leisurely daytime performance, however, and you'll hear just two of these songs, the pee-ah-wee and the wee-ooo.