Behavioural correlates of monogamy in the noisy miner, Manorina melanocephala

Mating behaviour of female cooperatively breeding noisy miners was examined. Dow & Whitmore (1990, Cooperative Breeding in Birds (Ed. by P. B. Stacey & W. D. Koenig), pp. 559-592, Cambridge: Cambridge University Press) suggested that female noisy miners mate promiscuously to recruit males as helpers to their nests, and that the benefit of doing so might be (1) increased genetic variability of their broods or (2) increased survival of their offspring as a direct result of multi-male care. Multilocus DNA profiling has since shown that 96.5% of nestlings resulted from monogamous matings and that extra-group and multiple paternity within broods were rare (Poldmaa et al. 1995, Behav. Ecol. Sociobiol.37, 137-143). In this study, strong behavioural correlates of monogamy were found. A breeding female associated more often with only one male in her social group, and most of the female's sexual behaviours were directed towards this male. Females were observed copulating repeatedly with the same male, but never with more than one male. Home ranges of breeding females rarely overlapped with each other, but home ranges of breeding males overlapped greatly. Furthermore, a greater percentage of a female's home range was shared with that of her genetic mate than with those of other males. Thus, behavioural evidence is consistent with the genetic evidence that noisy miners mate monogamously in some populations.1997The Association for the Study of Animal Behaviour