Allison Shultz and I have a new preprint available on EcoEvoRxiv: Community-sourced sightings of atypical birds can be used to understand the evolution of color and pattern. We’re really excited to discuss our ideas on leucistic birds and how these rare sightings can be useful to the scientific community! Find the preprint here: https://ecoevorxiv.org/fhkev/
Abstract: Birds are known for their brilliant colors and extraordinary patterns. Sightings of individuals with atypical plumage often cause considerable excitement in the birding public, but the difficulty of studying these one-off sightings means they have received less attention by the scientific community. In this perspective, we argue that sightings of individuals with atypical plumage hold the potential to further our understanding of the evolution of plumage color and patterning in birds. As a demonstration, we focus on sightings of leucistic individuals—those that lack melanin across the body or in certain feather patches—and outline two case studies. First, we discuss the potential for understanding carotenoid pigmentation with these sightings. Leucism influences melanins, but not carotenoids, and so with these sightings the extent and distribution of carotenoids across the body are unmasked. In a leucistic individual, carotenoids may or may not be more extensive than what is typically visible and this could help to understand the energetic costs and constraints that are involved in obtaining, processing, and depositing carotenoids in different species. Second, we discuss how partial leucism could provide insights into plumage pattern evolution. We demonstrate that one can use the many observations present on community science platforms to identify repeated patterns in different partially leucistic individuals of the same species, and match these to patches present in related species. These patterns could be the result of shared underlying genetic variation that controls plumage patterning in birds over a variety of evolutionary distances. With these case studies we outline just a few potential lines of inquiry that are possible with sightings of these atypical individuals. We encourage researchers to take full advantage of these chance sightings when they occur and database managers to make it possible to more easily tag photos or sightings of individuals with atypical plumage.