Birdsong Broadcasts Information about the Singer

Birdsongs vary in complexity: some repeat a simple basic unit; others are more elaborate (Figure 1). The principal roles of birdsong are territory defense and mate selection (Ball and Hulse, 1998) although other information also can be encoded in stereotyped songs. In the black capped chickadee, for example, individuals’ warning calls encode information about the size of intruding predators, such as owls – the chickadees then cooperate to mount a suitable defence (in the form of “mobbing” the predator)(Templeton, et al. 2005).

Figure 1  Songs of Three Bird Species
For each species, the top trace shows the exact sound pattern detected by a sensitive microphone. The bottom trace shows the same pattern analyzed by a sound spectrograph, which reveals the amount of energy in different sound frequencies at each moment. (After Greenewalt, 1968.)

A bird is more likely to learn the song of another species if its tutor is a live bird rather than a recording, suggesting that social stimuli direct the attention of developing birds to an appropriate “mentor,” whose song they copy (Baptista and Petrinovich, 1986).