Abstracts Psychology

Birdsong communication and perception: field and laboratory studies

by John Michael Burt

This dissertation involves two different research projects. In the first project, I conducted two field playback experiments to examine the function and scope of song matching by male song sparrows (Melospiza melodia ). The first playback experiment tested whether song matching functions as a threat signal. Subjects responded more strongly to playback of shared neighbor songs that matched their own song than to playback of non-matching songs. When matched, subjects either responded aggressively and stayed on the same song type, or responded weakly and switched to another type. The results suggest that song matching functions as a threat signal, and that when matched, birds signal escalation by staying on-type, and de-escalation by switching off-type. In the second playback experiment, I tested whether song sparrows would song match playback of songs not in their repertoire (non-shared song types). Birds matched the introductory elements of two different categories of non-shared stimulus songs. Birds therefore can song match other birds even if they don't share any song types, suggesting that matching may occur widely, even in populations with low song sharing. The second research project examined the neural basis of song perception in female canaries (Serinus canarius ). This project involved two operant conditioning experiments. In the first experiment, I studied the effect of lesions to the song nucleus IMAN on birds' abilities to discriminate different categories of acoustic stimuli. I trained female canaries to discriminate between sets of simple synthetic sounds, complex synthetic sounds, canary songs, and song sparrow songs. Subjects then received IMAN lesions, and were tested again on the same stimuli. Complete IMAN lesions caused general auditory deficits, suggesting that the nucleus IMAN in females is involved in broad auditory perception. The second operant experiment tested how the song nucleus HVc is involved in auditory perception. Different female canaries were trained with the same methods as the first study, with the exception that HVc rather than IMAN lesions were given. In contrast to the first lesion study, birds with HVc lesions showed discrimination deficits specific to canary song, suggesting that HVc in females is involved in conspecific song perception.