Maternal protectiveness in feral horses: responses to intraspecific and interspecific sources of risk

In most mammalian species, mothers must protect offspring from multiple sources of risk. In Australia, feral horses, Equus ferus caballus, have naturalized in many ecosystems, and foals are at risk from both predation by dingoes and sexually selected infanticide by nonpaternal stallions. This study tested maternal responses to these two forms of risk: risk of predation through dingo call playbacks and infanticide risk through a comparison of maternal protectiveness of foals in single- and multistallion bands. Mares were more vigilant and spent more time close to foals in bands with multiple resident stallions, where there is a higher risk of infanticide, relative to bands with a single stallion. Dominant stallions spent more time close to foals following the dingo call playbacks, indicating that stallions may play an important role in detecting and protecting foals from interspecific sources of risk. There was no significant increase in maternal protectiveness in response to dingo call playbacks, indicating that mares did not perceive dingo calls to be an immediate threat to foals. While predators were present, infanticide risk appeared to be the most significant modifier of maternal behaviour in this study.