Dissertation Research: Adaptive Basis of Delayed Maturation

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The bright coloration of birds has always intrigued ornithologists, yet relatively few studies have specifically addressed the adaptive value of bright breeding plumage. This study examines two aspects of plumage coloration in male and female Purple Martins: why do older birds have a brightly colored plumage, and why do young birds have a dull, subadult breeding plumage? This will be the first intensive study of Purple Martins in a natural habitat. Plumage dyeing experiments will determine the role that plumage color plays in a birds ability to defend its nesting site from competitors. The intensity of competition for nesting cavities and young birds' use of specific behavioral tactics to compete with older birds for opportunities to breed will be evaluated. Observations of aggressive interactions between subadult and adult birds will determine whether young birds are subject to less aggression because of their non-threatening, subadult plumage.