The social factor in song learning in american sparrows

Author: Lu Yang

Introduction

The ability to communicate is an adaptive trait that has evolved many times. Songs, in particular, are very complex signals found in insects, frogs, and birds and are most predominantly used by males to attract mates and/or compete with other males (Searcy&Anderson 1986). Among the animal taxa that use songs as a means of communication, songbirds (suborder Passerini) are unique in that their songs are not entirely genetically based (unlike a cricket chirp or a frog croak). Instead, songbirds learn songs through social interactions. We know this because juveniles raised in acoustic isolation develop abnormal songs (Marler 1970b). In this way and many others, songbirds’ songs are similar to human speech (see Box 4; Doupe&Kuhl 1999). Furthermore, song learning in birds is a great model for studying social learning in other animals, especially humans (see Box 4; Brainard&Doupe 2002).

Biologists have been trying to decipher the meaning behind bird songs since the 18th century (Baker 2001). Like many areas of biology, studies of bird songs have been greatly influenced by Darwin’s theory of evolution by natural selection, which spurred biologists to investigate deeper into the adaptive value of songs as form of communication. Only recently has serious progress been made in understanding song learning in songbirds, incited by Marler’s claim that song learning in birds has many parallels with speech learning in humans (Marler 1970a). Since then, numerous studies have been done on songbirds, although song learning, especially the social learning of songs, is still a relatively poorly understood topic.