Categorization of song notes in great tits: which acoustic features are used and why?

Abstract

An operant procedure was employed to determine which acoustic parameters great tits, Parus major, used to categorize song notes. Birds were trained first to discriminate between two synthetic song notes. These sounds were models of naturally occurring song notes and differed from one another in five acoustic parameters. Once subjects learnt to discriminate between the two training notes, they were tested with notes that presented all combinations of the five parameters. Responses to these sounds showed that great tits relied almost exclusively on note frequency to form categories; amplitude modulation, frequency modulation and the interaction between frequency and amplitude were all used to a much lesser extent. Note duration, inter-note interval and all other interaction effects did not influence categorization. A second experiment indicated that the importance of frequency can be explained by the fact that birds are particularly sensitive to differences in this feature.