Date of Award

Spring 5-6-2019

Document Type

Thesis

Degree Name

Bachelor of Arts

Department

Biology

First Advisor

Dr. Natalie A. Wright

Abstract

The tasks of reproduction, particularly parental care, are intimately tied to a bird’s movement. In many territorial passerines like Eastern bluebirds (Sialia sialis), males and females divide the work of caring for offspring unequally, and may thus alter their flight behavior in different ways to accomplish their respective nesting responsibilities. Significant differences in flight requirements between the sexes could focus selection on phenotypic traits that strengthen their ability to perform these tasks, leading to increased sexual dimorphism in traits like wing and tail shape and flight muscle mass. However, before we can speculate over potentials for selection on flight morphology related to different reproductive behaviors, we must first characterize behavioral differences in how the sexes use their flight. In this paper, we record patterns of change in voluntary flight behavior among eight breeding pairs of Eastern bluebirds across the rural Ohio summer breeding season. We found that the sexes altered their flight habits in conjunction with their nesting responsibilities. Specifically, females flew faster and changed their takeoff flight behavior between nesting phases while males did not substantially alter their takeoff flight patterns throughout the breeding season. Conversely, females landed at consistently fast speeds across the nesting cycle while males flew to their boxes more quickly in later nesting phases in correspondence with their increasing parental duties. This study provides empirical support that the sexes invest in flight in proportion to their investment in reproduction.

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