Interspecific Competition Affects Avian Personality, Assortative Mating, and Reproductive Success

Animal personality is thought to influence monogamous relationships by better allowing mates to coordinate territory defense and parental care behaviors. Aggressive territorial defense and boldness to potential predators are often important and ecologically relevant animal personality traits; however, the effects of heterogeneous social environments on the expression of assortative mating, personality, and behavioral syndromes are poorly understood. Eastern bluebirds are secondary cavity nesting birds that are facing a changing social environment in western NC. Tree swallows are expanding their range southward and have been in the field site for < 40 years. Tree swallows are highly aggressive and compete with bluebirds for limited nesting cavities. This new selection pressure may interfere with otherwise adaptive personality traits. This thesis aims to understand the ways that interspecific competition with a highly aggressive species may shape individual behavior and affect reproductive success in cavity nesting birds. Here, I examined how interspecific competition with tree swallows affects the propensity of paired male and female Eastern bluebirds to mate assortatively for behavior and how that may affect reproductive success. Furthermore, I examined how interspecific competition may affect behavior in an attempt to understand how the environment plays a role in shaping animal personality and plasticity.