Mate guarding and social mating system in male common chameleons (Chamaeleo chamaeleon)

Abstract

Male common chameleons Chamaeleo chamaeleon actively followed the female closely as a typical mate guarding behaviour during the mating season. Guarding behaviour and spatial organization were studied in 34 radio-tagged males in a population in southern Spain during three summers. Timing and extent of guarding were highly variable among males. Overall, guarding started on 16 August (range 28 July 5 September, n = 34) and ended on 4 September (range 21 August 15 September, n = 24) lasting 13.4 days (range 0 46 days, n = 30). Males showed a polygynous serial-type mating system where males sequentially guarded (and mated) several females during the breeding season but only one at a time. The number of guarded females (mean 2.8, range 0-8, n = 34) and number of mates per male (mean 0.7, range 0-3, n = 34) were also highly variable among males. In general, guarding males abandoned the females soon after mating in association with clear signs that females were no longer receptive. Males showed a remarkably complex spatial organization in close association with the home range of guarded females. Guarding behaviour resulted in territorial behaviour, and 'stable' as well as 'mobile' territories were recorded. In 'stable' territories, males defended non-overlapping areas where the home range of one female or more was included. Although monogamy was the predominant mating system recorded in this population, social polygyny occurred in all study years. Polygynous groups were only feasible because females aggregated in small-sized areas without apparent symptoms of intrasexual competition. Breeding asynchrony of females seems to influence this complex mating system as more competitive (large) males mated with large (early reproducing) females and small (late reproducing) ones (cf. Cuadrado, 1999). Most aggressive interactions were male-male chasing of a solitary intruder by a guarding male. A removal experiment of guarding males revealed that newcomers were small-sized males, suggesting that an important fraction of males were acting as floaters searching for mating opportunities. Male characteristics (especially size and body weight) were the main factors influencing the spatial organization and the reproductive success of males in this population.