Seabirds that live in hyperdense colonies during their breeding season– which includes a lot of penguins– are given to fairly high rates of murder: sometimes the most expedient way to resolve the stress of having an amount of nesting space measured in inches is to kill your neighbor. Or your neighbor's chick.
But there's other ways to solve problems and acquire more of what you need... so sometimes they'll lift their tail for someone besides their chosen mate and, in exchange, acquire physical goods like food or a really choice rock (great for nest-building!).
Honestly given their alternatives I commend them for it. Get your ideal rock WITHOUT anyone dying! Win win!
