Multi Female Bob Light DV - Female belly colour and bobbing behaviour advertise sexual receptivity in a pelagic-spawning coral reef fish

Female nuptial signals (FNSs) advertise reproductive state, individual quality, and are used in intrasexual competition. I explored whether pelagic-spawning pink-belly wrasse (Halichoeres margaritaceus) used red belly colouration and a unique bobbing behaviour as FNSs to advertise spawning readiness. I examined (i) if there was a temporal pattern in belly colour and incidence of bobbing, as each related to spawning; (ii) response of female belly colouration during male courtship behaviours; and (iii) pink belly area as it related to body area and bobbing rate. Temporal patterns were detected, females displayed ephemeral red belly colour and bobbing behaviour prior to spawning; females displaying red belly colouration elicited more courtship behaviour from males than females with white or pink belly colouration, and larger females displayed larger red belly areas. Benefits to advertising spawning readiness in pink-belly wrasse are discussed, including a reduction in mate-searching costs and potential for increased reproductive success through sex-change.