Date of Award

Spring 5-4-2026

Document Type

Thesis

Degree Name

Bachelor of Arts

Department

Biology

First Advisor

Iris Levin, PhD

Abstract

In species where extra-pair paternity (EPP) is common, males can allocate effort towards mate guarding, pursuing extra-pair copulations, and pre-hatch parental investment (e.g., incubation) to optimize reproductive success. Individual and mate quality as well as environmental factors can be used to inform decisions on how to allocate this effort. We investigated mate guarding, male incubation, and rates of extra-pair mating behavior of North American barn swallows (Hirundo rustica erythrogaster). To determine the relative importance of individual and mate quality for these behaviors, we used video recordings of active nests during the laying period, when the focal female was fertile, and incubation, when the female was not fertile. Additionally, all nests in the colony were monitored for breeding activity in order to calculate colony breeding synchrony. All adults and nestlings were genotyped to assign parentage, including extra-pair fathers. We used generalized linear models to test the Differential Allocation, Trade-Off, and Good Parent hypotheses to evaluate how mate guarding, male incubation, and EPP were related to traits of the focal individual, the social mate, and aspects of the environment. We found evidence for the Trade-Off Hypothesis through alternative age-related reproductive strategies, as older males spent less time mate guarding, sired more EP offspring, and had overall greater reproductive success than males breeding for the first time. Additionally, we found evidence for the Good Parent Hypothesis as males with redder ventral plumage put more effort into incubation, suggesting that ventral color may be an honest signal of parental investment. During periods of higher breeding synchrony, we found that males spent more time mate guarding and less time incubating. Females with darker ventral plumage were mate guarded less than paler females corroborating prior work suggesting potential differences in social dominance based on female ventral plumage color.

Rights Statement

All rights reserved. This copy is provided to the Kenyon Community solely for individual academic use. For any other use, please contact the copyright holder for permission.

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