ABS 2022
Automatic tracking of receiver’s movements during courtship interactions in spotted bowerbirds  
Giovanni Spezie1, Daniel C. Mann1, Job Knoester1, Leonida Fusani1,2. 1Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Vienna, Austria; 2Department of Behavioural and Cognitive Biology, University of Vienna, Vienna, Vienna, Austria

Spotted bowerbirds (Ptilonorhynchus maculatus) perform a vigorous courtship choreography on dedicated display structures – bowers – that are built and defended by one resident male. Bower owners tolerate the presence of immature, subordinate males at bowers, yet the role of these males has received little attention. One possibility for the presence of subordinate males at bower sites is that these younger males are learning the skills required for successful sexual signalling. For example, as vigorous courtship can startle receivers, practicing at adults’ bowers may allow these males to refine their ability to modulate display intensity. In this study, we trained a machine learning algorithm to track receivers’ movements during video-recorded courtship interactions. We measured the displacement of female receivers before and after high-intensity display elements, in order to assess if bower owners are more able to modulate display vigor than subordinate males. Contrary to our predictions, our results show that bower owners evoked stronger startle responses in receivers than subordinate males, and that males were equally responsive to receivers’ behaviour during courtship.