Morphological Changes Predict Inter-Seasonal Reproductive Performance In the North American Barn Swallow

Wildrick, Rachel

Undergraduate Honors Thesis

Morphological Changes Predict Inter-Seasonal Reproductive Performance In the North American Barn Swallow Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/fx719m88k

Abstract

Differential allocation between providing costly parental care and self-preservation is a well-known trade off in evolutionary theory. Across a variety of vertebrate taxa, a pattern exists where younger individuals tend to produce less offspring than older individuals after the onset of reproduction. I present data from a three-year study in a population of North American barn swallows Hirundo rustica erythrogaster to determine whether there is a pattern of age-related increases in reproduction and analyze how within-individual (1) site fidelity, (2) social mate, and (3) changes in morphology affect patterns of seasonal reproductive success, defined as the total number of young fledged in a given breeding season. Over the course of this study, I did not detect a clear pattern of increases in reproduction with age. Interestingly, significant changes in morphology between years predicted reproductive performance; females that minimized growth in tail streamers between 2008 and 2009 had greater reproductive performance. Males that became darker had greater reproductive performance only between 2008 and 2009. These relationships were not detected in the years between 2009 and 2010. I did not find that site fidelity or mate familiarity significantly impacted reproductive performance, in contrast to what was concluded in previous work. These analyses of intrinsic, morphological changes within individuals indicate that there are important underlying agerelated mechanisms of reproductive performance.

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