Date of Award

2-2011

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Organismic and Evolutionary Biology

First Advisor

Jeffrey Podos

Second Advisor

Ethan D. Clotfelter

Third Advisor

Elizabeth M. Jakob

Subject Categories

Biology | Other Cell and Developmental Biology

Abstract

Aspects of the behavioral ecology of bird song learning are examined in three parts. First, an approach from image analysis is extended to allow rapid, quantitative description of animal sounds. In this approach, sounds are summarized as sets of time-frequency-amplitude landmarks. Second, the role of dawn song in tree swallow (Tachycineta bicolor) breeding biology is examined. Song syllable sharing among tree swallows was found to be high among birds nesting at the same site, but sharing was lower between birds nesting at different sites. When birds nested at different sites, the distance between those sites was not related to the amount of difference between the birds' syllable repertoire compositions. All tree swallow song repertoires did not remain constant during the breeding season; some individuals added new syllable types, others modified existing types. Singing performance was correlated with reproductive success in tree swallows: males that sang more precise repetitions of their syllable types attracted more extra-pair mates. Furthermore, pairwise comparisons between the social and genetic fathers of extra-pair young found that the genetic fathers averaged higher syllable consistency than the cuckolded males. Third, a comparative study of the phylogenetic distribution of vocal mimicry examined the evolutionary history of song learning in oscine passerines. Vocal mimicry, defined as the habitual incorporation of heterospecific sounds into song displays, was found in twenty-eight separate clades of oscines. These clades were found in every major oscine superfamily, but made up a higher proportion of daughter groups within the most ancient superfamilies of oscines. The most plesiomorphic lineages of oscines were found to contain many highly-skilled mimics. These observations support the hypothesis that the course of song learning in oscines has run repeatedly from permissive learning rules that permit mimicry to restrictive learning rules that limit mimicry.

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