Is song–type matching a conventional signal of aggressive intentions?

Abstract

Song-type matching is a singing strategy found in some oscine songbirds with repertoires of song types and at least partial sharing of song types between males. Males reply to the song of a rival male by subsequently singing the same song type. For type matching to serve as an e¡ective long-distance threat signal, it must be backed up by some probability of aggressive approach and impose some type of cost on senders that minimizes the temptation to blu¡. Western subspecies of the song sparrow exhibit moderate levels of song-type sharing between adjacent males and sometimes type match in response to playback of song types they possess in their repertoires. Interactive playback experiments were used in order to examine the subsequent behaviour of type-matching birds and to quantify the responses of focal birds to type-matching versus non-matching stimuli. Birds that chose to type match the playback of a shared song type subsequently approached the speaker much more aggressively than birds that did not type match. Moreover, birds approached a type-matching stimulus much more aggressively than a non-matching stimulus. These results and consideration of alternatives suggest that type matching in song sparrows is a conventional signal in which honesty is maintained by a receiver retaliation cost against blu¡ers.

Eavesdropping and signal matching in visual courtship displays of spiders

“…The most interesting finding is that courtship rates of focal male spiders varied with tapping rates of the male exemplars to which they were exposed, suggesting signal matching or rate synchronization, which has previously been seen primarily in the acoustic communication of vertebrates, such as birds, fish, anurans and lizards [31][32][33][34], and chorusing insects [35]. Our findings suggest that male wolf spiders may be able to gain information about female location by eavesdropping on visual courtship displays of others and are able to adjust their subsequent performance to match that of rivals.…”

Juvenile sparrows preferentially eavesdrop on adult song interactions

“…For example, one obvious method of learning new vocalizations might involve a juvenile repeating what he hears an adult sing. However, in most songbirds, repeating the same song type, or 'song-matching', is considered an aggressive signal (Krebs et al 1981;Burt et al 2001;Vehrencamp 2001), and potentially could provoke a chase or attack by the adult 'tutor'. Although the inhibitory effect of direct interactions may still be important, the results of the present study suggest that eavesdropping on interactions may have unique benefits.…”

Is bird song a reliable signal of aggressive intent?

“…These latter signals appear to be conventional signals (Vehrencamp 2001), not vulnerability handicap signals, and below, we discuss three features of Searcy et al's experimental setup that might have masked the relationship between these signals and the sender's subsequent attack behavior.…”

“…Burt et al (2001), Vehrencamp (2001), Molles and Vehrencamp (2001), and Vehrencamp et al (2007), for instance, have provided evidence that song-type matching is associated with more aggressive behavior and that it is stabilized by receiver retaliation: playing back matching song types to territorial owners causes them to approach the playback speaker faster and more closely than in response to other song types. A shortcoming of these studies is that their measurement of reliability hinges on a proxy of aggressiveness: how near the bird comes to the speaker.…”