Female Songbirds: Why They Learn Songs but Rarely Sing

Male songbirds sing primarily to establish territoriality and to announce their availability as mates. Females generally do not sing, but they learn songs anyway. Why?

Females learn songs for three main reasons: to use their knowledge as an aid in choosing mates, to help males in various singing rituals, and, among certain birds under certain circumstances, to sing their own songs as females.

Male and female songbirds learn their songs in much the same way that humans learn to speak. There is an early stage, often while still in the nest, of absorbing the basic song elements of the species. Soon the bird practices with a "subsong," like a human baby babbling with various sounds it has heard from adults. Then comes the stage of the "plastic song," or "rehearsal song," in which the young bird experiments by combining sounds it learns with sounds it invents. Finally comes the mature bird's adult song.

Birds apparently commit their songs to memory by learning one small sound unit, called a "phoneme" (the equivalent of a human syllable), at a time. Eventually the bird recombines the units into a full song.

Phonemes in the adult song consist of some syllables that the bird learned early in life from its neighbors (thus giving the bird's song a local dialect), some syllables that are the bird's own variations of learned sounds, and other syllables that the bird invents. For example, in the swamp sparrow's twelve-syllable song, five or six syllables are exact copies of learned sounds, one or two are variations of learned sounds, and five or six are the bird's own inventions.

Adult female songbirds draw on their knowledge of songs to assist them in their selection of breeding partners. A female uses that knowledge in three ways: to avoid males singing too much like her father, to avoid males singing too much unlike her father, and to accept a male singing in the general dialect of her local population.