Trait polymorphisms are a perennially popular topic of study in ecology and evolutionary biology. The regularity of this heritable, melanin-based trait in the raptors has prompted research into its potential connections to aspects of life history such as immune response, foraging ecology, and mating systems. Because raptors are a non-monophyletic grouping of multiple orders, they can be leveraged to explore the eco-evolutionary drivers of recurrent plumage polymorphism phenotypes. This dissertation explores plumage polymorphism in the raptors, including a characterization and literature review, an exploration into the genomic basis of the trait in the Eastern Screech Owl (Megascops asio), and foundational work to develop the Red-tailed Hawk (Buteo jamaicensis) as a model system for exploring the development and maintenance trait polymorphisms in predatory species.