Date of Award

5-13-2008

Document Type

Thesis

Department

Biological Sciences

Abstract

The Lesser Antillean Bullfinch, Loxigilla noctis, broadly ranges throughout the Lesser Antilles, from St. Croix and St. John south to Grenada. Previously, nine different subspecies of L. noctis have been recognized including L. n. barbadensis, which is endemic to Barbados. In contrast to all other L. noctis taxa, L. n. barbadensis has been described as sexually monochromatic, with the loss of male's colorful plumage in this population. Following a recent survey of this taxon, the American Ornithologists' Union recently recognized L. n. barbadensis as a distinct biological species, the Barbados Bullfinch, L. barbadensis. Among other criteria, sexual monochromatism was cited as an important factor. However, the results of this study suggest that, in addition to sexual size dimorphism, reduced sexual dichromatism exists in this species, particularly in regard to coloration of the lower mandible. Examination of a suite of plumage characteristics using a binary logistic regression was able to correctly differentiate the sexes in 79.0% of individuals in our sample. This study raises new questions regarding the role of sexual selection in L. barbadensis.

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