Territoriality by the dawn's early light: the Neotropical owl butterfly Caligo idomenaeus (Nymphalidae: Brassolinae)

Abstract

Males of the Neotropical owl butterfly Caligo idomenaeus defend unusual dawn territories along dirt roads in the Linhares Forest Reserve, Espírito Santo, Brazil. The territories are notable for their wide spacing and the brief period in which owners are present. During mid-winter insects arrived on the territories shortly after 0550 h, as the last bright stars disappeared from the sky, and remained approximately 15 min before flying back into the forest. Dawn perching seemed unaffected by substrate temperatures as low as 12.5° C. Perches were about 100 m apart and resident butterflies returned to and seemingly repelled invaders from their territories on consecutive mornings. Territories contained no mate- rial resources. The brief dawn occupancy may be related to the activity period of receptive females and to predator risk in these large, palatable insects.