A critical overview of progress in studies of migration of dragonflies (Odonata: Anisoptera), with emphasis on North America

Migration by Odonata has been recorded sporadically for several centuries, but only recently have new technologies and a new wave of interest in these ancient insects sparked a concerted effort to understand the extent, behavioral mechanisms, adaptive significance, and ecological consequences of this phenomenon. Here I review our current knowledge of these sometimes spectacular flights, focusing on the few species in North America that are known to migrate more or less annually. One of these, the Common Green Darner, Anax junius, has been shown to traverse hundreds to thousands of kilometers from north to south during fall migration. Pantala flavescens (Wandering Glider) is plausibly inferred to make an overseas flight from India to East Africa with the Northeast Monsoon, although its migrations in North America are less well understood. Large scale movements of these and other species raises questions about population connectivity, ecosystem impacts, the nature and evolution of cues that initiate migration, and effects of climate change on these phenomena.