Atypical Song Reveals Spontaneously Developing Coordination between Multi-Modal Signals in Brown-Headed Cowbirds (Molothrus ater)

Amanda R Hoepfner,Franz Goller,Stephanie Ann White

doi:10.1371/journal.pone.0065525

Abstract

The courtship and dominance behavior of brown-headed cowbirds (Molothrus ater) consists of a multi-modal display, including song as well as postural and wing movements. The temporal sequences of the acoustic and the visual display are coordinated. In adult male cowbirds the largest wing movements of the display are synchronized with silent periods of song, but it is unknown how this coordination emerges during song development. Here we investigate how visual display features are coordinated with song by using atypical song sequence structure of isolation-reared male cowbirds. In birds with atypical song, all components of the visual display were highly similar to those of “normal” song displays, but their timing was slightly different. The number of maximal wing movement cycles of isolation-reared males was linked to the number of sound units in the song, and was therefore reduced during the abbreviated song types of isolates. These data indicate that young cowbirds do not need to be exposed to a model of the visual display during ontogeny and that there is synchronization with the temporal structure of song. A physiological link between respiratory and syringeal control of silent periods between sound units and wing movement cycles may be driving this synchronization.

Highlights

Many animals make simultaneous use of different sensory channels for communication
Could the respiratory movements of song provide a template for the wing movement pattern of the visual display? The results indicate that the wing movements of the visual display were adjusted to the altered song sequence, suggesting that the acoustic motor program guides the timing of the main movements of the visual display
The measurements of lowest wing position were labeled according to the silent period of the song with which they were associated according to the following convention: Low3 corresponds to the silent period preceding the last sound unit

Summary

Introduction

Many animals make simultaneous use of different sensory channels for communication. For example, birds frequently combine acoustic and visual signals in their elaborate territorial and courtship displays. The most elaborate wing movements are synchronized with the silent periods during the song ([2]; Figure 1).

Results

Conclusion