Mass reproductive wanderings of dragonflies of the genus Sympetrum (Odonata, Libellulidae)

摘要

The results of observing mass flights of some dragonflies of the genus Sympetrum forming tandems are presented. These tandems always fly against the wind, some of them landing for oviposition and then joining the flight again. This variant of migration behavior has been unexplained until now. A hypothesis is proposed according to which synchronous mass flights of dragonfly tandems facilitate the most uniform oviposition in all the suitable biotopes. The general direction of the flight depends on the wind. As the wind direction changes, the flight course of the tandems changes accordingly, so that the dragonflies cross the same territory several times, which leads to a denser and more uniform distribution of eggs. It is proposed to refer to this variant of flight as reproductive wanderings. Such a dispersal strategy can maintain the most uniform population density and a more stable abundance of some dragonfly species in the territories with unstable humidity.