Female Mating Preference and Reproductive Success in Eastern Bluebirds: Interacting Effects of Plumage Coloration and Genetic Compatibility

Abstract

In my dissertation, I used a combination of aviary-based experiments, field experiments and correlational research to fully explore the importance of mate choice and environmental heterogeneity on reproductive success in eastern bluebirds. In the first half of my dissertation (chapters 1, 2, and 3), I used aviary and field manipulations to tests the hypotheses that female mating preferences are based on male plumage ornamentation and genetic characteristics. In the second half of dissertation (chapters 4 and 5), I examined whether male characteristics and environmental factors influence reproductive success. In the first chapter, I examined female mating preferences in eastern bluebirds by utilized aviary-based mate-choice experiments. I found no evidence that female eastern bluebird chose mates based on their structural coloration. In the second chapter, I used a field-based design to again test female mate preferences for male ornamentation. To control for the influence of territory quality on female choice, I widowed dyads of males with adjacent territories. I found the more-ornamented and larger males did not attract females more quickly compared to the less-ornamented and smaller males, thus I found no evidence that females preferentially settled with the more-ornamented males. In third chapter, I used the same experimental design and tested the importance of male heterozygosity and the genetic compatibility of the pair on female preferences in the wild. I found that females preferred to pair with the most genetically compatible mates. In the fourth and fifth chapters, I focused on reproductive success of wild breeding eastern bluebirds. In the fourth chapter, I found that both male coloration and genetic compatibility of pairs predicted offspring quality. The relative importance of genetic compatibility versus mate ornamentation on nestling quality, however, varied with season. In the fifth chapter, I explored environmental factors that influence hatching failure. I found that the relative humidity measured from the nearest weather station was positively related to the likelihood that eggs would fail to hatch. I found no consistent relationship, however, between seasonality and hatching failure, nor did I find that pre-incubation nest temperatures predicted hatching failure.