This work reports on an infanticide attempt by a dominant resident male in a group of Alouatta caraya (Humboldt, 1812) on an extra-group infant in an Island in the Paraná river, Paraná, Brazil. The encounter of an infant-female pair with a resident male was brought about by human interference. Give the circumstances in which the event ocurred and the hierarchical position of the agressor, the social pathology hypothesis seems the most plausible explanation for such behavior.
Black and gold howler monkey; agressive behavior; social behavior; riparian Forest; invasive method