Influences On the Choice Between Territorial and Satellite Behaviour in Male Libellula Quadrimaculata Linn. (Odonata: Libellulidae)

Abstract

Territorial behaviour of male Libellula quadrimaculata Linn. was investigated at Wicken Fen, Cambridgeshire, in 1986. Males were intensely territorial, expelling any other males that flew into their territory. Territories were defended for the mating opportunities that they provided. As local population density increased a number of males adopted satellite behaviour, although most continued to behave territorially. Wingspan and hindwing length were significantly larger in satellites than in territorial males. The likelihood of satellite behaviour was not related to male age. There was also no difference in age between satellite-host pairs in which both individuals were of known age. Satellite males were not observed to mate successfully, though they did not suffer the costs associated with territorial defence. A series of removal experiments demonstrated that the satellites could take over a territory and behave aggressively to other males. Scaling factors may have an important function in forcing larger males to adopt the less successful satellite role. Notably, flight muscle content was lower than expected in larger individuals, which should result in lower power output per unit body weight, and thus lower maximum acceleration and manoeuverability. Territorial behaviour of male Libellula quadrimaculata Linn. was investigated at Wicken Fen, Cambridgeshire, in 1986. Males were intensely territorial, expelling any other males that flew into their territory. Territories were defended for the mating opportunities that they provided. As local population density increased a number of males adopted satellite behaviour, although most continued to behave territorially. Wingspan and hindwing length were significantly larger in satellites than in territorial males. The likelihood of satellite behaviour was not related to male age. There was also no difference in age between satellite-host pairs in which both individuals were of known age. Satellite males were not observed to mate successfully, though they did not suffer the costs associated with territorial defence. A series of removal experiments demonstrated that the satellites could take over a territory and behave aggressively to other males. Scaling factors may have an important function in forcing larger males to adopt the less successful satellite role. Notably, flight muscle content was lower than expected in larger individuals, which should result in lower power output per unit body weight, and thus lower maximum acceleration and manoeuverability.