Abstract
Summary (1)Both males and females in a population of Calopteryx maculata mated more than once in the course of a single afternoon. The possibility that females might mate with an intruder or with a neighbouring territory owner may have favoured the evolution of guarding behaviour by males. Territorial males employed non-contact guarding of their mates. They perched on vegetation overlooking the oviposition site and repelled intruder males from the area. (2)Territory owners were able to discriminate between females they had already mated and new arrivals. When previous mates left the oviposition site temporarily they usually were readmitted promptly by the resident male when they returned. New arrivals were usually courted, pursued and sometimes successfully mated, even if this meant briefly leaving an ovipositing mate unguarded in the territory. (3)Non-contact guarding is interpreted as an adaptation to permit a territorial male to acquire new mates even while guarding previous ones. Comparisons with othe...