New record of infanticide in Alouatta pigra: chance of betrayal of altruism

Abstract

The infanticide is a normal behavior in different animal species. In primates of the genus Alouatta infanticide it has been observed in polygamous groups where death of infants is caused by unrelated males when a pregnant female joins a family group, or when a new young male takes ownership harem other. An altruist behavior is developed by subordinate males, which they may help to the related dominant male in the defense of the group, but these altruism can be betrayed. In ≈ 6.58 ha fragment located in a highly fragmented landscape at municipality of Balancan (Tabasco), we made observations to a group of seven howler monkeys, and a lone adult male. We documented the fourth case of infanticide in Alouatta pigra in Mexico by a subordinate male. A. pigra groups with the highest number of females probably attract external male that trying to take control of the group. However, we suggest that the subordinate male could have taken advantage of the distraction of the group to made infanticide. Although the aultruist behavior in A. pigra is present, these coalition can be betrayed by selfish motivations, especially when subordinate males they presume better advantage to the dominant males, or the opportunity to take control of the group and their roles within it.