ADVANCES IN STUDIES OF AVIAN SOUND COMMUNICATION

Ground-breaking advances in the study of animal sound communication pe r se, and avian vocal behavior in particular, awaited instrumentation that enabled capture of sound signals for objective description and an alyses. Once these technological advances became generally available, a groundswell of activity in vocal studies, bioacoustics, provided the ''raw material'' for hypothesis testing pertaining to various biologi cal and evolutionary principles. All aspects of this field cannot be c overed in one review. Thus, themes developed herein deal primarily wit h questions of vocal acquisition such as factors affecting song learni ng, the sensitive phase and stimulus filtering hypotheses pertaining t o the learning process, the effect of vocal behavior on population dyn amics, the effect of hormones on the song learning process and product ion, photoperiod and song as they are related to gonadal recrudescence , advances in the neurophysiological control of song acquisition and p roduction, and the incidence of female song and function across taxa.