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Bird Molts and Plumages

Feathers, highly adaptable through evolution, are shaped by diverse environments—from open oceans to arctic zones—supporting birds across various ecosystems. Molt, the cyclic renewal of feathers, has facilitated the worldwide diversification of birds. Studying the evolution of molts and plumages, as well as describing molt patterns remains an active component of my research.

Molt as an Adaptive Process

Molt is more than mere feather renewal; for example, ptarmigans molt regularly to camouflage and evade predators, and many species exhibit seasonal changes in coloration to attract mates. In lowland tropical forests, the lack of seasonal constraints provides evolutionary flexibility to modify molt strategies—such as duration, intensity, and extent of feather replacement—to occupy new ecological niches. For example, our research indicates that altering molt intensity is important for understanding how small understory birds maintain large territories, making them the slowest molting birds on record. Future studies in my lab will explore how suspended molts in certain tropical bird lineages aid in their adaptation to environmental uncertainty.

Prealternate Molt and the Multistep Evolution of Seasonally Colorful Plumages

Working with Dr. Ryan Terrill, we found that migratory distance in New World Warblers (Parulidae) correlates with the extent of feather replacement during the prealternate molt. Birds migrating longer distances undergo more extensive molts, which is a necessary prerequisite to the development of vibrant breeding plumages. We propose that this molt pattern has evolved as an adaptation for replacing worn feathers in birds undergoing long migrations or residing in harsh environments. We hypothesize that sexual selection has co-opted the evolution of the prealternate molt to facilitate seasonal changes in breeding plumage. While this phenomenon is well-documented in warblers and European songbirds, it likely influences similar coloration changes in shorebirds, gulls, and even non-migratory grassland birds in Africa. Exploring the selective forces that gave rise to the evolution of prealternate molts and resulting breeding plumages remains an intriguing line of inquiry in my lab.

Describing molt patterns

In general, there has been a disproportionate interest in breeding and migratory ecology when compared to research focused on molt. Given my interest in bird banding, I have had the unique opportunity to study molt patterns in songbirds across the Neotropics and Afrotropics leading to a number of publications focused on describing molt at the hemispheric, regional, and taxonomic scales. Partnering with Dr. Erik Johnson, we published a book on Molt in Neotropical Birds which currently serves as a benchmark in knowledge surrounding molt patterns exhibited by understory Neotropical bird families. Currently, my lab is interested in using our collaborative banding datasets from Equatorial Guinea to begin describing molt and plumage patterns of understory birds from Central Africa.

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