Flight initiation distance in Lepidopterans is species-specific and positively related to starting distance

Escape behaviour is a critical component of invertebrate life history but is poorly studied. Flight initiation distance (FID) indexes escape propensity, and is well-studied in vertebrates but is entirely unstudied in Lepidopterans, despite their obvious escape behaviour. Here we test two general principles regarding FID as derived from studies of vertebrates to examine if they apply to Sri Lankan butterflies: 1) that FID is a species-specific trait and 2) that FID increases with Starting Distance, the distance at which the experimenter begins an approach. We collected 295 FIDs from 17 species and find that 1) FIDs are a tractable way of indexing butterfly escape and 2) both the general principles tested apply to butterfly escape. We also present FIDs of these species to encourage further data collection and comparative analysis of butterfly escape.