This study comes to a surprising conclusion: Humans and other primates may stay together to keep their babies from being killed by rival males. (sciencemag.org)
Male dogs might also urine mark when they find themselves in the presence of rival males. (pets.webmd.com)
He studied crabs on South African and Mozambican beaches and found males frequently defending the burrows of neighbouring females when rival males approached. (newscientist.com)