Visual effects in great bowerbird sexual displays and their implications for signal design.
It is often assumed that the primary purpose of a male's sexual display is to provide information about quality, or to strongly stimulate prospective mates, but other functions of courtship displays have been relatively neglected. Male great bowerbirds (Ptilonorhynchus nuchalis) construct bowers that exploit the female's predictable field of view (FOV) during courtship displays by creating forced perspective illusions, and the quality of illusion is a good predictor of mating success. Here, we present and discuss two additional components of male courtship displays that use the female's predetermined viewpoint: (i) the rapid and diverse flashing of coloured objects within her FOV and (ii) chromatic adaptation of the female's eyes that alters her perception of the colour of the displayed objects. Neither is directly related to mating success, but both are likely to increase signal efficacy, and may also be associated with attracting and holding the female's attention. Signal efficacy is constrained by trade-offs between the signal components; there are both positive and negative interactions within multicomponent signals. Important signal components may have a threshold effect on fitness rather than the often assumed linear relationship.
Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, , Waurn Ponds, Victoria 3216, Australia, School of Marine and Tropical Ecology, James Cook University, , Townsville, Queensland 4811, Australia.
John A
JA
Endler
Julie
J
Gaburro
Laura A
LA
Kelley
D000819:Animal Communication; D000818:Animals; D003118:Color Perception; D003380:Courtship; D005260:Female; D008297:Male; D052586:Mating Preference, Animal; D012726:Sexual Behavior, Animal / Q000502:physiology*; D020308:Songbirds / Q000502:physiology*
bowerbird; constraints; holding attention; illusions; sexual display; visual effects