Discrimination of male black-capped chickadee songs: relationship between acoustic preference and performance accuracy

Many species form social groups with dominance hierarchies. Often, individuals possess a status signal that indicates dominance rank. Songbirds produce songs that are used to attract mates or repel rivals, and acoustic features within songs can also indicate an individual's quality, including dominance rank. Acoustic status signals have been reported in the songs of male black-capped chickadees, Poecile atricapillus, a nonmigratory North American songbird. Here we used two operant conditioning tasks to examine acoustic preference for and discrimination of conspecific songs produced by males varying in dominance rank. We used a choice preference task to examine birds' preferences for listening to dominant or subordinate songs and conducted an instrumental learning task to determine whether chickadees considered dominant and subordinate songs as belonging to separate signal categories based on acoustic features. Overall, our results provide little evidence that birds used open-ended categorization when discriminating, but there is evidence that songs from different geographical regions may contain acoustic similarity based on dominance rank. Consistent with previous song discrimination studies with black-capped chickadees, we found sex differences in discrimination abilities, with females learning the discrimination faster than males. We also found evidence that performance accuracy during the instrumental learning task correlates with acoustic song preference. Overall, these results suggest that when biologically relevant signals (e.g. male songs) are used as stimuli during a perceptual task, the birds' responses may be differentially affected based on individual differences among the subjects performing the task (including sex and underlying preference) and the salience associated with the stimuli (e.g. dominance rank of the singer).