Reproductive restraint to avoid the costs of reproductive conflict in a cooperatively breeding mammal

The costs of reproductive conflict can be an important factor shaping the evolution of life histories in animal societies. These costs may change as individuals age and grow, and with within-group competition. Social costs of reproductive conflict have been invoked to explain why females might gain from delaying maturity or ceasing reproduction midway through life, but not in males. Here we analyze more than 20 years of data to understand how individual male banded mongooses adjust their reproductive activity in response to the costs of reproductive conflict. In banded mongooses groups multiple female breeders enter oestrus synchronously and males compete to mate guard the females. The oldest and heaviest males in the group gained the greatest share of paternity, while younger and lighter males obtained little or no paternity. Those lighter males that are reproductively active paid disproportionate survival costs. Our results suggest that by delaying or suppressing reproduction early in life, males may reduce their mortality. Males may also avoid inflicting costs on their male kin by queuing. These results from an egalitarian cooperative breeding mammal may provide a rare example of voluntary reproductive restraint, although we cannot discount reproductive suppression by rival males.