Visual communication and sexual selection ln a nocturnal bird species, Caprimulgus ruficollis, a balance between crypsis and conspicuousness

Cryptic protective mechanisms and the conspicuousness required to communica te result in a conflict of opposing selection. In the Red-necked Nightjar ( Caprimulgus ruficollis) a nocturnal bird, the use of a restricted signaling strategy provides an appropriate balance between these two selection force s. Conspicuous white wing and tail bands may have been favored by sexual se lection in this species. We studied the variation of visual signals and fou nd conspicuousness to be closely related to sex and age, being much higher in males and adults. This variation allows an individual to identify the re productive status of conspecifics, providing sexual selection a basis to se lect these visual signals in this and other nocturnal bird species. We beli eve that a relationship between restricted signaling strategy and sexually selected visual signals may occur in nocturnal species that use visual comu nication.