Behavioral Adaptation in the Courtships of Sub-adult Plumaged Male Satin Bowerbirds (Ptilonorhynchus violaceus)

Abstract

Male satin bowerbirds, Ptilonorhynchus violaceus, have complex displays involving multiple display elements that show age-related change over males' first 7 years. Sexual display of sub-adult plumaged (SAP) males with other SAP males appears to allow these males to practice and is of lower quality than that of adult males. In this study we initially attempted to assess age-related changes in SAP male display quality using a female dressed robot. We found that SAP male courtship with female and SAP male dressed robotic birds did not allow us to assess age-related change because these courtships were all of very short duration, much shorter than with live SAP males or courtships by adult males with live or robot receivers. We suggest that because SAP males have low quality displays they are unlikely to attract willing copulations from females who visit their bowers and may thus benefit more from rapid forced copulation than from practicing display with these visitors. Short courtships and copulations with male dressed robots which are rare in natural courtships may result from the failure of our robot to show behaviors that might typically indicate that they are males. These results suggest that SAP males use the behavior of courtship receivers to make decisions about how to respond to birds they court at their bowers.