Predator-elicited visual signal: why the turquoise-browed motmot wag-displays its racketed tail

Both sexes of the turquoise-browed motmot (Eumomota superciliosa)perform a wag-display in the presence of predators, wherebytheir long racketed tail is repeatedly rocked side-to-side ina pendulous fashion. I tested 3 hypotheses for the functionof the predator-elicited wag-display: 1) pursuit-deterrent signal,2) warning alarm signal, and 3) self-preservation alarm signal.These hypotheses were evaluated by testing whether the presenceof potential receivers (kin, conspecifics, mate) modified theway in which the wag-display was performed. Data on wag-displaywere collected when I experimentally presented predators tomotmots and when naturally occurring predators were observedat nesting colonies. The wag-display was performed by male andfemale motmots who were 1) alone and not within signaling distanceof conspecifics, 2) unpaired and therefore not signaling toa mate, and 3) paired but away from their mate. Motmots in thesecontexts performed the wag-display with similar probabilityand in a similar manner as individuals that were within signalingdistance of conspecifics, paired birds, and paired birds whowere near their mate. These results support the hypothesis thatthe predator-elicited wag-display is directed to the predatorand functions as a pursuit-deterrent signal.