Why Birds Sing

Of the many interesting sounds in nature, bird songs are the most charming. The song of birds is a sexual characteristic developed in the male during the nesting-season. It is closely re­lated in the first place with mating, and is one means by which the male attracts the attention of the fe­male during courtship; it continues, however, dur­ing most of the nesting-season. Occasionally the female has been known to sing, as with the rose­breasted grosbeak and cardinal. While singing is primarily a sexual instinct with the birds, yet it may probably be carried on for the aesthetic pleasure derived, as some birds seem to show appreciation of the harmony of music.

Season when birds sing. Spring and early summer is the season of bird song, but there is a great varia­tion as regards the time when different species begin and end their song. The first birds that come in the spring begin to sing at once, so that the song sea­son in the northern United States begins in March. The song of the later arrivals is added to these, till the height of the song season is reached in May. As the family cares begin to occupy the attention of the birds, they become more wary and busy, so that during June the volume of bird music gradually becomes less as the birds drop out of the chorus one by one. During July there is a still more marked decrease, till by the end of the month nearly all the birds have ceased singing, although a few continue well through the summer, such as the house wren and red-eyed vireo. When birds rear two broods, this tends to prolong the song season.

Time of day when birds sing. The bird chorus begins in the early morning at earliest daybreak and reaches its climax about sunrise and then declines till it is nearly over by the middle of the forenoon, although a few birds, like the wren, sing nearly all day long. During the middle of the day most of the birds are quiet. The chorus begins again late in the afternoon and continues till some time after sun­set. The evening chorus is not so vigorous and long­continued as the morning chorus, although some species of birds sing rather more in the afternoon than in the morning.

The birds do not all begin and end their morning song at the same time. Certain birds are usually among the first to begin, an hour or more before sunrise, such as the chipping sparrow, the robin, and the song sparrow, and as the morning advances other birds join the chorus. This order in which the different birds begin to sing is about the same from morning to morning.

Bird songs are of interest to mankind for two reasons: as a means of identifying the singer and as a source of pleasure on account of the musical harmonies produced, just as one enjoys human music. When the leaves on the trees have developed in the late springtime, it is often difficult to see the birds which may be behind the foliage. But if one knows the song of the bird, he can identify it without seeing it. It is a source of much pleasure to be able to recognize the voices of one's bird friends as he walks past their haunts.