Life in Color: Spontaneous Color Preference in Broad-tailed Hummingbirds (Selasphorus platycercus) & Plumage Color Evolution in the ‘Bee’ hummingbird clade

Abstract

The visual world of hummingbirds is one filled with color. For instance, studies have shown the hummingbirds utilize color in foraging decisions. Furthermore, plumage color can be utilized in both interspecific and intraspecific signaling among hummingbirds. Therefore, understanding the impact of color on the visual world of hummingbirds is crucial to understanding evolutionary patterns and behaviors in these species. In this study, I sought to build upon previous research surrounding the effects of color on spontaneous flower preference in Broad-tailed Hummingbirds (Selasphorus platycercus) across both sexes. I conducted an experiment at the Rocky Mountain Biological Laboratory in Colorado that examined the spontaneous flower color preferences of hummingbirds. Furthermore, UV-blocking paper was utilized to evaluate the spontaneous preference of UV vs. non-UV reflecting flowers. Additionally, I complemented this with a study conducted at the American Museum of Natural History in which I characterized the plumage color of 7 species within the Bee hummingbird clade within a tetrahedral color space. Utilizing these color data, metrics such as the diversity of feather colors were mapped onto phylogenies separated by sex in order to qualitatively analyze evolutionary patterns in plumage color development. Based on the results, a large portion of both male and female hummingbirds demonstrated a spontaneous preference for red flowers. However, there was no significant difference in the number of visits to UV-blocking vs. UV-reflecting flowers. In regard to plumage color, males tended to be more colorful than their female counterparts. Those species that were closely related exhibited a greater degree of similarity in color metrics when mapped on a phylogeny. These results will thereby provide more extensive knowledge concerning how color impacts the visual perception of hummingbirds in order to better grasp how hummingbirds interact with the world around them.