A Quantitative Analysis of the Dawn Chorus: Temporal Selection for Communicatory Optimization

Abstract

This study describes a mathematical model designed to explore the relationships between sound transmission and microclimatic conditions present at different times of the day in different habitats. The model includes all attenuation mechanisms and is used to illuminate possible reasons for the dawn chorus obseved in birds and primates under a diverse array of environmental conditions. Also explored are the possible effects of calling height and calling frequency on broadcast coverage. Solely from the point of view of atmospheric attenuation mechanisms, early morning microclimatic conditions are as optimal for sound propagation as will be present at any other time during the day or night. Depending on the environment, calls voiced at such times are up to 20 times more effective in area of broadcast coverage than the same amplitude signal broadcast at midday. Such an advantage goes far in explaining why many animal species have selected these times for territorial and/or mate attracting communicatory announc...