Manakin display and visiting behaviour: a comparative test of sensory drive

The conspicuousness of bird plumages may vary with the ambient light. Therefore, two behavioural predictions of the sensory drive hypothesis are that males should prefer to display and that females should prefer to visit males under specific ambient light conditions that enhance communication efficiency. Here we investigate patterns of male display and female attendance at male display sites under different ambient light conditions in a clade of five closely related species of manakins (Pipridae). Continuous focal observations and video recordings showed that in four of five species, the frequency of male display in different ambient light conditions correlated with their availability at their display sites, and that males showed no preference for displaying under specific ambient light conditions. But in Corapipo gutturalis, males showed a strong preference for displaying in shade and sunny gap environments. Females showed no preference for visiting male display sites under specific ambient light conditions, nor did they prefer males with the strongest ambient light display preferences. Male display and female visiting patterns for most of the manakin species studied were inconsistent with behavioural predictions of sensory drive. However, male C. gutturalis have evolved a preference for displaying in specific light conditions that is a derived behaviour novelty within the clade. As predicted by sensory drive, this behavioural novelty is phylogenetically congruent with a change in sensory environment: a decrease in the frequency of cloudy conditions at display sites. Behavioural and environmental novelties in C. gutturalis are not phylogenetically congruent with the evolution of the glossy, blue-black and white plumage in the ancestor of all Corapipo. Further tests of the sensory drive hypotheses are recommended, such as whether display sites are nonrandom samples of the sensory environment or whether male plumage colours are adapted for efficient signalling in specific ambient light conditions.