Systematic ‘infanticide’ of unrelated young occurs in several animal species. For carnivores and primates, infanticidal actions are mainly sexually motivated. A study in Scientific Reports by researchers of Vetmeduni Vienna has shown for the first time that also male poison frogs selectively eat other males’ offspring—after having taken over their rivals’ territories. They were thus able to demonstrate that even simple decision rules can mediate a complex behavioral pattern such as parental care.