Eye for an eyespot: how iridescent plumage ocelli influence peacock mating success.
Each of the multicolored eyespots (ocelli) on the peacock's (Pavo cristatus) train is a complex structure with a purple-black center surrounded by concentric blue-green and bronze-gold regions. To investigate the influence of all 3 of these colors on male mating success, we used a physiological model of peafowl vision to quantify those colors as females would perceive them during male courtship displays. Males display at about 45° to the right of the sun's azimuth (on average) with the female directly in front, so we investigated how colors would be perceived when illuminated at 30°, 45°, and 60° to the right of a female observer. We studied 34 males displaying at leks in 3 feral populations and quantified their copulation success and the colors of their eyespots. Eyespot coloration explained half of the observed variation in peacock mating success, with the hue and iridescence of the blue-green patch being the most important color variables. When we experimentally masked ocelli on 9 males, their copulation success declined almost to 0, supporting the idea that the eyespots are a major focus of female attention and not a trait that is simply correlated with something else that influences female choice. Thus, our study shows that the blue-green eyespot color overwhelmingly influences peacock mating success. The influence of the other eyespot colors on male success is minimal at best, raising questions about their function.