SYDNEY, Australia — It was a young penguin colony, and all but one of the couples were pretty bad parents.

They would get distracted from their nests, go for a swim or play, and so neglected eggs were getting cold, likely never to hatch. This was normal for inexperienced penguins, and the aquarium managers didn’t worry. Next mating season would be better.

One couple, though, was extraordinary. Not because they were the colony’s only gay penguins, though they were, but because Sphen and Magic looked like they would make great, diligent, careful egg-warming parents. They made the biggest nest, and they sat on it constantly.

Curious, the aquarium managers gave the two males a dummy egg. They took to it. And so then, when a particularly negligent heterosexual penguin couple looked to be leaving an egg exposed (females lay two, but usually only one survives), the aquarium workers figured they would give it to Sphen and Magic.