Adult songbirds have complex and elaborate songs. In most species, only males sing, although both sexes communicate using simple calls. Songs are used to establish and defend territories and to attract mates. Most birds have in-born vocalizations that require no practice or learning. But most baby songbirds—and some species of hummingbirds—must learn by hearing adult songs. (Exceptions among Greenwood’s more common patients are flycatchers, doves, and pigeons.) Babies don’t usually develop adult song until long after they have fledged. But if they don’t hear adults during the appropriate learning period, they tend to develop simpler songs with a smaller range of notes than do birds raised in the wild. Since song complexity and richness attract females to singing males, males with less interesting songs are at a clear disadvantage. Even though females don’t usually sing, they too need to hear adult songs as they grow up or they may not recognize and respond to an appropriate male’s song.
Young birds don’t produce adult songs until their first fall, at the earliest. But they seem to store the appropriate notes and rhythms, for later practicing. Research suggests that babies may learn songs best 10 – 50 days after hatching. For Greenwood’s babies, though, this prime learning period is when they’re in our care. If the orphaned or abandoned baby birds that Greenwood staff and volunteers raise don’t hear appropriate adult songs, they may never be able to successfully compete and reproduce in the wild.
Hearing a live bird is the best way to learn, but babies can also learn from recordings. House Finches, American Robins, and House Sparrows can hear plenty of their songs from the wild birds around Greenwood. But other species need help to have a chance to develop fully. A number of years ago, several of us at Greenwood put together a list of Greenwood’s most common species. Cornell Laboratory of Ornithology then compiled a CD of these songs from the vast audio catalog of Macaulay Library, repeating the 9 most common ones several times. (If you’ve never heard of it, Macaulay Library is the world’s largest repository of wildlife audio and video recordings. Check it out!) Although this CD has the songs of many different species, the babies learn only their own songs because their brains filter out all but the relevant ones. (After all, in the wild, the air is filled with singing from all sorts of birds. It’s a birdsong jungle out there.) So when people work in the baby bird nursery, we encourage them to play the CD whenever they can, to give the babies a taste of their songs. Even just an occasional playing can help.
In this way, we not only give the baby birds in our care nutritious food and a clean, safe environment. We also try to send them back to the wild with the communication tools they need to lead full, rich, productive adult lives. It’s easy—all we have to do is hit that “play” button and the babies will do the rest.