Quantifying iridescent coloration in animals: a method for improving repeatability

摘要: Quantification of animal colors is important to a variety fields research, especially those dealing with visual communication and sexual selection. Most are easily measured using well-established spectrophotometric techniques. However, the unique characteristics iridescent present particular challenges opportunities quantify novel color metrics. Due fine-scale angle dependence coloration, metrics, such as hue brightness, must be methods that allow for repeatable comparison across individuals (e.g., by carefully controlling measuring viewing geometry). Here, we explain how optical should considered when developing measurement techniques, describe pitfalls some commonly used recommend improved metrics (angular degree change breadth reflectance) quantifying color. In particular, most studies birds date have less than ideal procedures not provided repeatability estimates their methods. For example, demonstrate here coloration from overlapping patches feathers may problematic, argue against do control geometry. We iridescence at maximal reflectance angles an apparatus allows sample rotation, compare this technique other gorget crown Anna’s hummingbirds (Calypte anna). Our quantification angular change, found measurements single highly both within feather samples among individual.