Evidence of predation and disturbance events at Heliconius (Insecta: Lepidoptera: Nymphalidae) nocturnal aggregations in Panama and Costa Rica

Many unpalatable species use conspicuous colours to give a clear signal (aposematism) to predators of their noxiousness, and in many cases the message can be strengthened through aggregations. Several species of neotropical aposematic Heliconius butterflies present an interesting case because, although they form nocturnal aggregations, the colours on their wings are not detectable at night and there are no known nocturnal predators. Müllerian mimicry is probably the most important phenomenon that makes Heliconius butterflies one of the most successful neotropical groups but many other ecological adaptations have contributed to their success. These adaptations include availability of different models, wing colour adaptation to background light, and specific diurnal flying ranges as well as exclusive nocturnal roosting height ranges for each mimicry ring. By providing nocturnal habitat segregation, but most importantly protection from nocturnal predators, Heliconius nocturnal aggregations could have evolved to contribute to the success of coexistent Müllerian mimicry rings. The present work reports for the first time evidence of nocturnal predation attempts by bats and disturbance events at Heliconius roosting sites.