Assaying lepidopteran flight directionality with non‐invasive methods that permit repeated use and release after testing

Abstract

Abstract Research into lepidopteran flight behaviour using techniques such as disappearance bearing (DB) observations and flight simulator (FS) trials provide important information on how organisms orient using environmental cues. These techniques possess limitations, however, which preclude their use for rare or threatened species. DB observations limit the amount and diversity of data that can be collected from individuals. FS trials can be high risk, involving invasive, terminal procedures. We develop a new non‐invasive tethering technique for lepidopterans, demonstrate this method using eight different species and include a video tutorial. We describe the means necessary to conduct FS trials (open‐loop assay) and test the tethered butterflies from different species in outdoor FS tests. We describe the use of DB observations for assaying the directionality of free‐flying individuals (closed‐loop assay). We test our methods using fall migratory monarch butterflies, Danaus plexippus, and examine the flight orientation of the same individuals using both assay methods. Flight simulator and DB techniques each yield useful and complementary results when both are applied to the same individuals. Using both assays on the same individual, as part of our new ‘catch–test–release’ (CTR) method, permits the integrated acquisition of different types of behavioural information, in a manner not done previously. The non‐invasive CTR technique has significant implications for movement research with lepidopteran species of variable conservation status or that are considered pests. Our CTR technique aids conservation science by expanding the scope of species and the questions that can be tested, as individuals are re‐released into nature unharmed after experimentation.