Investigating the consistency of mate-locating behavior in the territorialbutterfly Hypolimnas bolina (Lepidoptera : Nymphalidae)

The study of butterfly behavior has afforded valuable insights in to the ev olution of alternative mating tactics Two hypotheses derived from this area of research contend that (1) territoriality is only viable under low to mo derate conspecific densities (due to the costs of site defence) and (2) per ching may be employed only when thermal conditions constrain flight activit y. These hypotheses were evaluated by investigating mate locating behavior in Hypolimnas bolina, a territorial species that is naturally subject to va riation in population density and weather conditions. Male behavior was cha rted throughout the day during a period of high population density at art e ncounter site in tropical Australia. Perching was the primary tactic, altho ugh a small proportion of individuals patrolled nonaggressively in the afte rnoon. Population-level male behavior failed to support predictions drawn f rom either the "territory economics" or "thermal constraint" hypotheses. Fi rst, the proportion of perching males and the number of aggressive conspeci fic interactions (per male) increased with increasing male density at the s ite. Second few males patrolled at the honest, brightest rime of day (appro ximately midday), and the diel distribution of perchers did not emulate the "U-shaped" distribution shown by the occurrence of dorsal basking behavior . These results show that perching in this species is not a suboptimal tact ic employed when temperatures constrain flight activity but may represent t he best method of locating receptive females. Ar this stage the reproductiv e significance of the observed patrolling behavior remains obscure.