Forced Copulations and Female Contact Guarding at a High Male Density in a Calopterygid Damselfly

Abstract

Territorial males of Calopteryx damselflies court females on territories that contain oviposition substrates. Nonterritorial males try to mate without courtship but very rarely obtain matings because females fail to bring up their abdomen to engage genitalia. Here 1 report the results of observations made on a very high-density population of Calopteryx haemorrhoidalis in central Italy. Mating activity was intense, and during 40 h of observat ion in an 8-m section of the stream, 209 matings were recorded (a maximum of 17 matings h -1 ). Males were continuously disturbing ovipositing females and tried to achieve tandem forcibly. Of 84 cases, males achieved forced tandem in 53, and 49 ended with copulation. Forced tandems were the most common method to obtain a mating in this population (55% of 65 matings). Males guarded females after forced or courtship copulations and, in some cases, maintained physical contact with their mate, by perching on her wings. Confusion was common and males guarded nonmates frequently, which suggests that they were unable to recognize their mate individually.