Wandering and territoriality in Libellula depressa L. (Anisoptera: Libellulidae)

Upon returning to the water after maturation, the male of L. depressa behaves as a wanderer (i.e. non territorial), but he turns to behave territorial after mating. The territory is established in the place where his female has oviposited. This conclusion is based on: (1) the decrease of the male flight range, (2) the decrease of the inter-perch distance and (3) the decrease of the distance between perch sites and opposition site, after copulation. If mating is not repeated in the territory in the following days, territorial attachment weakens and the male begins to wander again, until he mates a new female. Territorial behaviour is then shown at the new place. This alternation between wandering and territoriality can be repeated relative to each of successive copulations. The strong aggressiveness shown by the male in the area where he has guarded a female permits him to displace all the other males from that site. Thus, non-contact guarding probably functions in permitting the male to keep control of the territory, which would be lost if another male mated in it while the owner was tandem-guarding a female.