Bird Songs and Calls

Birds use song both in courtship and to define areas of territory. Both of these are communicative purposes: the bird is passing specific messages to other members of its species. Birds communicate for other reasons as well: a blackbird, for instance, will make a sharp “pink-pink” sound when there is a cat nearby, which warns other birds in the neighborhood of the danger.

William Thorpe(1961)studied the behavior of gannets in a colony containing many thousands of birds. Thorpe found that when a bird was returning to its nest, it would drift on an updraft of air from the bottom of the cliff upwards, calling as it went. When the bird on the nest heard its mate calling, it would call in reply, showing that each bird’s call could act as an identification signal. Thorpe also calculated that a bird might have as many as fifteen or sixteen different kinds of calls, each serving a different function.

J. R. Krebs(1976) investigated how birds seem to sing more intensively in the early morning–the”dawn chorus”. By investigating what the birds actually did during each day, and how much time they spent on each activity, Krebs found that the dawn chorus serves a largely territorial function. The early morning is not a particularly good time for gathering food, because it is dark, so visibility is lower, and it is also cold, so many insects are still inactive. On the other hand, at this time many birds move around looking for living space, so establishing and defending a territory is necessary. Birdsong is not just territorial, of course. A bird’s song can serve a dual purpose: it can be used to defend a territory and by indicating to a prospective mate that the singer has a territory to defend, can also attract a female bird.

P. J. B. Slater(1981)suggested that bird calls and birdsong are partly learned from other birds. He found that chaffinches which had been hand-reared and had not heard other wild birds made an entirely different kind of “chink” call from that of wild birds. In one case, Slater observed a laboratory chaffinch in a duet with wild sparrow outside the window of the laboratory. The chaffinch imitated the sparrow’s “cheep” whenever the sparrow produced it. Slater concluded that learning through copying is an important part of the way in which birds acquire their songs. Slater also found that individual chaffinches can have up to five different types of song. Some of these are personal, sung by that bird alone. Others are shared by several birds. In some cases too, Slater observed chaffinches singing songs which were almost identical to those sung by others, but with just a note or two different-possibly because the bird had made an error in copying the song from another.

Slater studied a population of 40 chaffinches on the Orkney Islands and found that among them they had seventeen different song types. So it was not a matter each bird having its own individual songs–there was a considerable amount of sharing. Slater found that this sharing related to geographical distribution, but that the boundaries were not distinct enough for it to be accurately described as a dialect, or regional variety of a song. Instead, there was considerable overlap between the songs sung in one area and those sung in an adjoining one, but gradually the overlap would become less, until birds a long distance away from one another would be singing entirely different songs.

In 1970, Peter Marler proposed that birdsong and speech were directly comparable in certain key respects and that the study of birdsong might provide psychologists with some useful indicators as to the nature and development of speech in human beings. One of the parallels which Marler identified was the way that both humans and birds show a strong genetic predisposition to pick up and imitate certain sounds rather than others. Marler showed that young birds will learn the songs of their own species if they are played to them when young, but they will ignore songs of birds from other species. Similarly, young human beings are surrounded by all kinds of sounds and noises, but it is the human voice to which they listen most closely and human speech which they imitate.?

1.William Thorpe(1961)studied the behavior of gannets in a colony containing many thousands of birds. Thorpe found that when a bird was returning to its nest, it would drift on an updraft of air from the bottom of the cliff upwards, calling as it went. When the bird on the nest heard its mate calling, it would call in reply, showing that each bird’s call could act as an identification signal. Thorpe also?calculated?that a bird might have as many as fifteen or sixteen different kinds of calls, each serving a different function.?