PLIGHT PHYSIOLOGY OF NEOTROPICAL BUTTERFLIES - ALLOMETRY OF AIRSPEEDSDURING NATURAL FREE-FLIGHT

Airspeed measurements during natural free flight were made on a total of 270 neotropical butterflies representing 62 species. Morphological data were obtained from the same individuals for which airspeeds had b een determined. Flight speed was positively correlated with body mass, thoracic mass and wing loading. Controlling for body mass, higher win g loadings were correlated with increased flight speed. Flight speed a nd wing aspect ratio were negatively correlated. No consistent correla tions were found between airspeed and wing length, wing area or body l ength. Released butterflies and butterflies encountered in natural fre e flight did not differ substantially in flight speed allometry. The o bserved scaling of flight speeds was similar to that derived for a muc h smaller sample of butterflies flying in an insectary, although absol ute values of flight speed were approximately three times higher in na tural flight and correlation coefficients of allometric regressions we re typically lower. These results suggest that butterfly airspeeds und er natural conditions can reasonably be predicted from morphological m easurements, and that studying flight in enclosed spaces preserves the allometry of flight speeds.