Do Cordulegaster males defend territories? A preliminary investigation of mating strategies in Cordulegaster boltoni (Donovan) (Anisoptera: Cordulegasteridae)

The behaviour of C. boltoni was observed and the presence of individually marked males was recorded continuously at a rivulet in the Fichtelgebirge, southeastern Germany. The males spend a considerable amount of their time patrolling up and down along rivulets. They are aggressive towards each other, but do not restrict their flight range and do not delimit territories. Females only rarely visit rivulets for mating and ovipositing, without obvious site preference. — The intraspecific aggression effects a spacing-out of the males and possibly a regulation of male density at the mating place (or rendezvous site). This behaviour of being aggressive towards competitors but not delimiting territories may be an optimal mating strategy for Cordulegaster males in their specific ecological situation.