Chinstrap Penguin - Roy and Silo

Roy and Silo

In 2004, two male chinstrap penguins named Roy and Silo in Central Park Zoo, New York City, formed a pair-bond and took turns trying to “hatch” a rock; this was substituted by a keeper for a fertile egg, and the pair subsequently hatched and raised the chick. Penguins, by their nature, hatch eggs and are social creatures. A children's book, And Tango Makes Three, was written based on this event.