Use of sound and aerial chases in sexual recognition in Neotropical Hamadryas butterflies (Nymphalidae)

Abstract

Neotropical Hamadryas butterflies are notorious for the clicking noise they produce in flight. Tests of the sound production capacity of nine species of Hamadryas and observations on aerial interactions of six species showed that, among the three species groups, only males of the feronia group produced sounds, whereas females of all species and males of the februa and laodamia groups never did so. Most of the aerial interactions occurred during mid-day, generally initiated by males in exploratory flights. Chasers were always males. Males engaging in chases with other males continually produced clicking sounds during the interactions whereas males chasing females usually restricted their auditory displays to the initial phase of the pursuit. In a cage containing 24 individuals of both sexes of six species of Hamadryas, males were involved in 100% of the aerial interactions observed, with one single male participating in 57% of them. The most chased individuals were females and males of H. feronia. There was no relation between the number of times an individual successfully defended a feeding perch and the number of aerial chases initiated. Sound production is probably involved in finding mates, while aerial chases may be used in the establishment of a dominance hierarchy among male Hamadryas.