Term of Award

Fall 2006

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Department

Department of Biology

Committee Chair

C. Ray Chandler

Committee Member 1

Steve Vives

Committee Member 2

Daniel Gleason

Abstract

Bright plumage coloration in most birds is thought to be a product of sexual selection. Brighter, more-ornamented males are preferred by females because their plumage conveys information regarding the quality of the individual. One measure of male quality is willingness to invest in offspring. In birds, investment is usually measured as the rate at which nestlings are provisioned. However there are other forms of parental investment. The purpose of this study is to quantify the relationship between two measures of parental investment and their association with structural plumage coloration in male Eastern Bluebirds (Sialia sialis). I found there was no correlation between nestling provisioning and nest defense for males or females. Males with brighter UVblue plumage tend to provision nestlings at higher rates and more-ornamented males tend to defend the nest from a predator at lower rates. This study suggests that structural coloration is an indicator of the ability of a male to invest in its young. However, because nestling provisioning and nest defense (the two main male parental investments) were not correlated, I suggest that nestling provisioning and nest defense are not equivalent measures of parental investment, and condition-dependent traits have different relationships to different measures of parental investment.

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