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.