Wind drift compensation, flyways, and conservation of diurnal, migrant Neotropical Lepidoptera

Abstract

The identification and conservation of migration corridors requires that migrating organisms are goal-oriented and capable of adjusting for drifting off-course. Migrating birds are capable of wind drift compensation over water, but no insects have been demonstrated to possess such capabilities. Using vector analysis of individual airspeeds, track directions, ambient windspeeds and wind directions, we quantified within-individual variation in compensation for wind drift in two migrating butterfly and one moth species in natural free flight over a lake. The pierid Aphrissa statira and nymphalid Marpesia chiron butterflies were capable of wind drift compensation, whereas Urania fulgens (Uraniidae) moths were incapable of course correction. Changes in heading across the lake were not indicative of the use of a single landmark for orientation, and thus the use of two landmarks or the vector orientation of the surface beneath the insect were potential orientation cues. Among migrating Aphrissa statira, Marpesia chiron, Phoebis argante, and Urania fulgens, individual headings corrected at least partly for wind drift. For Aphrissa, short-distance compensation over water extended to a long-distance flyway across the isthmus of Panama that is suitable for conservation.