Day-flying butterflies remain day-flying in a Polynesian, bat-free habitat

To test the theory that insectivorous bats have selected for diurnality in earless butterflies I compared the nocturnal flight patterns of three speci es of nymphalid butterflies on the bat-free Pacific island of Moorea with t hose of three nymphalids in the hat-inhabited habitat of Queensland, Austra lia. Nocturnal flight, measured as the ratio of deep night (1h following su nset to lh preceding sunrise) to twilight night (1h before sunset to 30 min after sunrise) activity did not differ significantly between the two locat ions, nor did the percentage of individuals active and I conclude that livi ng in a bat-released habitat has not produced nocturnal flight in these ins ects. This result is surprising considering the potential advantages of esc aping diurnally active predators and suggests that physiological adaptation s (e.g. thermoregulation and/or vision) currently constrain these insects t o diurnal flight. Since taxonomic records suggest that gene flow does not e xist with bat-exposed conspecifics, I suggest that insufficient time has el apsed since these species migrated to Moorea to have resulted in major phen otypic changes such as diel flight preferences.