Small Bird, Big Song
As spring moves into summer, birdsong is in full voice. The winter wren, weighing only one third of an ounce, is tiny in stature but boasts an energetic song made up of over 100 individual notes.
Why such a big song from such a small bird? The winter wren makes its home among root tangles and boulders, and unlike birds of open spaces, birds particular to dense, enclosed spaces need a strong song to have it carry far.
Wrens are classified as songbirds, a group whose brains have evolved to learn calls of great complexity and variation. Young songbirds learn their species' song from adults. By comparison, non-songbirds emit simple vocalizations—a croak, a quack, a squawk—that are innate, not learned.
In experiments where young songbirds were raised isolated from adults, they improvised among themselves to develop vocalizations unrelated to their species. In the wild, this would doom them in courtship, as females judge vocal skills as a sign of a potential mate's age and experience. A female's first choice is often older males, experienced survivors who advertise their superior skills through more developed songs.
Hear an example of the winter wren's song: