Mass influx and unusual roosting behaviour of Anax ephippiger on the island of Lanzarote (Odonata: Aeshnidae)

Abstract

. A mass influx of migrating Anax ephippiger was observed on Lanzarote, an island of the Canaries lacking surface waters. Individuals of both sexes roosted close together on palm leaves, all of them with their abdomen conspicuously curved upward. We suggest that this posture may be the result of a trade-off between roosting together as close as possible and obtaining enough spatial freedom for rapid simultaneous take-offs of the individuals when disturbed.