BIRD SONGS
Hearing Is Believing
Recognizing birds by their song, even before you see them, is a challenge. The chickadee ("chik-a-dee-dee-dee") and the eastern phoebe ("fee-bee") are easy; they say their own names. However, not everyone can identify the "rusty hinge," the sound often attributed in field guides to the red-winged blackbird. Just as knowing what to look for enables you to identify birds by sight, knowing what to listen for helps you distinguish birds by sound. For years researchers have used state-of-the-art equipment to record and study songbird sounds. But only recently have simpler, less expensive tools become available. Technology has reached the consumer level of bird songs in the form of transmitters and other devices. A recent product available from your local Wild Bird Center store is the pocket sized Birdsong Identiflyer. This hand-held device plays the song of any of 10 bird species on a "songcard'' by pushing a button next to the image of the bird you wish to hear. And then there are the timepieces, which play the sound of a different bird each hour. They come in all sizes from wall clocks to wristwatches, and the numbers are represented by 12 different species.
Songs of Summer
Rewards abound when feeding our feathered friends. They bring their free spirits, bright colors and constant chatter into our lives. But is it just chatter?
The sounds that birds make vary with the season, the age and the sex of the bird. Although we tend to think of all bird sounds as "songs," there are other vocalizations that they make. "Calls," which are short and sometimes harsh, are given by both males and females and serve as danger warnings as well as keeping a pair in close communication. Some birds have as many as 20 distinct calls, which together with the song make up a bird's vocal repertoire. Not all of the birds' sounds are given by both sexes. In many species only the male sings; however, both the male and female Baltimore oriole and northern cardinal sing. People generally are unable to hear a difference between the songs of the cardinals, but a study of their harmonics found that females use more overtones, which creates a somewhat nasal effect.
Scientists theorize that hormone levels cause the difference in sound. Some sounds are given only during certain times of the year. Singing, for example, used by most species primarily to attract mates and defend nesting territories, occurs mostly in spring. Birds you hear singing later in the summer may be starting a second brood with a brief courtship, or they may have lost a mate and are trying to attract a new one. There is one bird sound that you will hear only from mid to late summer, the repeated call of fledglings. When a bird first leaves the nest, it flies a short distance to some protected spot. Then, to help the parents establish its location in order to bring food, the fledglings invoke loud vocalizations. They are easily recognizable by their plaintive but insistent quality.
As you sit on your patio this summer, listen to the sounds the birds are making all around you. It will be a lovely respite from the cacophony of the artificial noises that clog our busy days.
Songs Without Words May Be Full of Meaning
Birdsong is a language without words, but certainly with meaning. While there are some answers to the "why" of bird singing, none are complete.
One function certainly is that some birds sing to stake a claim to their own nesting area. Certain migrating males, arriving first in spring, sing to proclaim a particular territory as their own. Then, as the females come in from their southern winter homes, the male sings to win a mate. After that, he stops singing, possibly because he might call attention to his presence and attract predators. Once the nestlings are hatched, the male is occupied finding food to fill hungry mouths. Some species, however, raise more than one brood, so the musical efforts of the male may be renewed in midsummer. Singing virtually stops after nesting season, but some birds sing during a brief period in the early fall after molting has occurred.
The time of day, as well as the time of year, seems to influence bird song. If you ever have been awakened at dawn by a bird chorus, you may have noticed that different species sing in their own moment. Late in the afternoon, bird songs seem softer than at daybreak; dusk prompts the vesper sparrow to sing, while the whippoorwill is vocal only at night.
Ornithologists tell us that all of the simple call notes of a bird are instinctive, but that true song may be partly inherited and partly or entirely learned. Some birds incorporate the songs of other birds in their own singing. The jay and catbird have a talent for imitating other birds' sounds, but the mockingbird tops the charts by continually mimicking not only the calls and songs of other birds, but frogs and even noises such as sirens.
Why Do Birds Sing? Are They Just Happy?
One reason we feed wild birds around our homes is that we presume they appreciate a little help from their friends. Another reason is that we simply enjoy having them around. We like watching their antics, seeing their colors -- and listening to them. Each bird species is capable of making a variety of sounds that it uses to communicate with other birds. These sounds are songs, which usually are long and complex, and calls, which usually are short and simple. By encouraging birds to our yards, we are more liable to hear all their vocalizations. Songbirds account for nearly half of the world's 9,600 different species and about 40% of the 750 found in North America. For the most part, it is the males that "sing" -- a consistently repeated pattern of tones. But in a few species, including Northern cardinals, Baltimore orioles and rose-breasted grosbeaks, the female also occasionally breaks into song. Birds generally sing more in the early morning and late afternoon.
While singing behavior varies among species, most takes place during the breeding season. Lags occur during the short mating period and when the young are being cared for. Singing pretty much stops when the nestling period is over. At least in the North, winter ends singing -- except for Northern cardinals. They seem to sing year 'round. The songs of birds are learned, not inherited, much as with humans. Within a couple of months, fledglings will have developed a "subsong" that matures into an adult primary song in perhaps a year. If a white-crowned sparrow grew up with, for example, only song sparrows around, it would learn song-sparrow songs. Although chipping sparrows have only one basic song, song sparrows may have 10, some wrens more than 100 and -- as many of you well know -- mockingbirds a couple hundred that they voice endlessly. The species that sing create musical sounds by their syrinx. This is a kind of double voice box at the bottom of the windpipe. Two sets of membranes and muscles where the windpipe branches into the lungs vibrate at high frequencies as air is exhaled. In fact, while singing, a bird can alternate exhaling between its two lungs and thereby sing in harmony with itself. Usually a male that is defending a territory or attracting a mate will sing from one of the highest or most conspicuous spots available. This favorite spot may be used time and time again. On the other hand, some birds, such as larks, bobolinks and buntings, sing while flying. And while birds usually do not sing around their nests, a few sing a quiet "whisper song" that can be heard for only a few yards. In the final analysis, different birds sing different songs but usually for much the same reasons. One of those just might be that they are well fed, stress free and happy.