For wild birds, sex reversal may be more common than ornithologists originally believed. In one instance, a genetically male kookaburra had a distended oviduct. The male bird had recently laid an egg. “One of the key findings was that 92% of sex-reversed birds were genetically female but had male reproductive organs,” said Potvin. “We also discovered a genetically male kookaburra who was reproductively active with large follicles and a distended oviduct, indicating recent egg production”—our male, egg-laying bird friend.