1 Broad-tailed hummingbird coloration and sun orientation 1 Two ways to display: male hummingbirds show different 2 color-display tactics based on sun orientation 3 Running header: Broad-tailed hummingbird coloration and sun orientation 4 5 Richard K. Simpson1* and Kevin J. McGraw1 6 1School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501 7 *Corresponding Author. Email:
[email protected]; Phone: (480) 965-2593 8 9 ABSTRACT 10 Animals exhibit a diversity of ornaments and courtship behaviors, which often co- 11 occur and are used for communication. The sensory drive hypothesis states that these 12 traits evolved and vary due to interactions with each other, the environment, and signal 13 receiver. However, interactions between colorful ornaments and courtship behaviors, 14 specifically in relation to environmental variation, remain poorly understood. We studied 15 male iridescent plumage (gorgets), display behavior, and sun orientation during courtship 16 flights (shuttle displays) in broad-tailed hummingbirds (Selasphorus platycercus), to 17 understand how these traits interact in both space and time to produce the perceived 18 coloration of males. We also tested how gorget coloration varies among males based on 19 their plumage, behavioral, and morphological characteristics. In contrast with previous 20 work on other animals, we found that displaying males did not directionally face the sun, 21 but instead displayed on a continuum of solar orientation angles. The gorgets of males 22 who tended to face the sun during their displays appeared flashier (i.e. exhibited greater 23 color/brightness changes), brighter, and more colorful, whereas the gorgets of males who 2 Broad-tailed hummingbird coloration and sun orientation 24 tended to not face the sun were more consistently reflective (i.e.