A pair of male penguins who have nested together for six years apparently broke up when a female penguin became available, say caretakers at the San Francisco Zoo.
Harry and Pepper, a pair of Magellanic penguins, started nesting together in 2003 and incubated an egg last year.
However, zoo keepers confirmed in early July that Harry has been nesting with a female penguin, Linda, for several months.
Linda and Harry became friendly shortly after her long-term partner, Fig, passed away in the winter. Within a week of Fig's passing, Harry was spotted in Linda's burrow.
Harry and Pepper had a violent confrontation and zookeepers removed Pepper from the penguin colony. He has since been reinstated, but zookeepers say they're concerned the upcoming penguin moulting season in late July could cause upheaval among penguin couples.
Zookeepers say it's not the first time Linda has been involved in such a triangle. Several years ago, she left her longtime partner and moved in with Fig shortly after his partner passed away.