THE VOICE OF THE CHAFFINCH AND ITS FUNCTION AS A LANGUAGE

Abstract

Summary.: The voice of the Chaffinch has been studied by making recordings and analysing them on a sonograph. The contexts in which each call is given are described. The 14 basic calls are flight, social, aggressive and injury calls, three alarm calls, subsong and song, three courtship calls and the begging calls of nestlings and fledglings. With their variations they give 21 different signals. The ontogeny of certain calls and the occurrence of intermediate forms suggest how voice may have evolved in the Chaffinch. A hypothetical ancestral type agrees with certain Cardueline finches, implying a closer relationship than recent anatomical studies suggest. Unlike many displays, calls often occur without an obvious conflict in motivation. The voice of Chaffinches reared in isolation is usually normal, but song is usually abnormal and in nature is perfected by learning from other birds. The social call is sometimes abnormal and may sometimes be modified by learning under natural conditions. The communicatory function of voice has been assessed by studying the responses of other Chaffinches to it. By comparison with other contexts in which the same response occurs, a list of “information received” is constructed. The recipient responds as though this has been received. Four general types of information are involved, social and environmental, identifying and locating. Inter‐specific communication occurs with other woodland Passerines, especially through alarm calls. The alarm calls are of a type difficult for predators to locate. Different families have independently evolved the same type of call for this purpose. Other alarm calls of many species, used to draw attention to the position of a predator, are adapted to be easy to locate. The general structure of many calls can be understood in terms of the need to facilitate or hinder location of the calling bird. There are other factors governing the form of voice, especially the need to differ from the calls of other sympatric species. This only applies to calls communicating certain types of information. Some of those exempt from this need for divergence may be especially useful in phylogenetic study. The two main types of response to voice are related to the different types of information conveyed by the calls. Mechanisms of response are discussed, and the differences between the languages of the Chaffinch and of man.