Date of Award

2014

Publication Type

Doctoral Thesis

Degree Name

Ph.D.

Department

Biological Sciences

Keywords

Biological sciences, Psychology, Animal communication, Bioacustic, Calls, Duets, Songs

Supervisor

Mennill, Daniel J.

Rights

info:eu-repo/semantics/openAccess

Abstract

Acoustic communication is a critical component of social interactions in birds. There are relatively few quantitative studies of the vocal behaviour of tropical bird species, in spite of the rich avian biodiversity in the tropics and the extensive variety of vocalizations they produce. This lack of information inhibits our ability to understand the behaviour and ecology of tropical birds, and impairs our ability to perform comparative analyses from an evolutionary perspective. In this dissertation, I study the vocalizations of three species of tropical ground-sparrow: Melozone biarcuata (Prevost's Ground-sparrow), Melozone kieneri (Rusty-crowned Ground-sparrow), and Melozone leucotis (White-eared Ground-sparrow). I provide the first description of the vocalizations of each species, and demonstrate that all three ground-sparrows produce three main categories of vocalizations: calls, solo songs, and duets. I present results of a sound transmission experiment where I broadcast and re-recorded solo songs and duets through thicket habitats. I found that both vocalizations show similar patterns of degradation and attenuation with distance, suggesting that they facilitate communication with receivers at similar distances. I evaluate individual distinctiveness in the songs of male White-eared Ground-sparrows and the persistence of distinctive characteristics over time. I found that male White-eared Ground-sparrows sing individually distinctive songs. Uniquely, I found the frequency with which males sing different song types is also individually distinctive, and this feature varies little between recording sessions. I present results of a playback experiment to evaluate whether White-eared Ground-sparrows use calls, solo songs, and duets to discriminate conspecific from heterospecific competitors. I show that ground-sparrows display more intense responses to conspecific vocalizations than congeneric vocalizations, suggesting that they discriminate competitors from non-competitor species. Finally, I provide analyses of the morphology, plumage patterns, colour reflectance, male solo songs, and calls of individuals from northern and southern subspecies of Melozone biarcuata. My data show that the southern subspecies exhibits substantial phenotypic differences, on par with other subspecies complexes where species status has been recognized. I argue that M. b. cabanisi should be treated as a species separate from M. biarcuata (Prevost's Ground-Sparrow) and propose that it be called Cabanis' Ground-Sparrow ( Melozone cabanisi ).

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