SOCIAL-BEHAVIOR, MATING SYSTEM AND TESTES SIZE IN CUIS (GALEA MUSTELOIDES)

Social behaviour, mating system and testes size were investigated in c uis (Galea musteloides) in order to elucidate the social mechanisms in an obviously promiscuous rodent. Therefore, quantitative behavioural measures were recorded with a total of more than 200 h observation tim e in 4 groups of animals (1-4 adult males; 3-5 adult females in 12-25 m(2) enclosures). Testes and body masses were determined in 21 males. The most conspicuous feature in all groups of cuis was the daily rhyth m of huddling. Short-lasting phases of high activity alternated severa l times daily with phases of inactivity during which all or nearly all members huddled together with close bodily contact. The mating system was promiscuous. In none of the 8 mating chases did the alpha male su cceed in preventing the lower ranking males from copulation. Promiscuo us mating was achieved by the females' behaviour, which attracted the attention of all the males and made it impossible for a single male to monopolize her. The males' relative testes size was extremely high, w hich thus strongly supports the supposition that a promiscuous mating system is typical for cuis. Surprising for such a mating system were t he high levels of intermale aggression which were even found when no f emale was receptive, and although clear dominance relationships existe d between the males. The females were also organized in linear dominan ce hierarchies. In contrast to the males, however, they frequently dir ected socio-positive behaviour towards conspecifics of the same sex.