Male and female birds are often quite different. Looking at two individuals of radically different color, it’s sometimes easy to forget this. I often talk to people who think they have multiple kinds ...

Male cardinals are red. Female cardinals are tan. The odd bird that's been roosting outside John and Shirley Caldwell's kitchen in Erie, Pennsylvania, is an even split of both. Divided down the middle ...

Researchers have discovered an extraordinary, vibrantly colored tropical bird with "female" feathers down one side of its body and "male" feathers down the other. Female green honeycreepers ...

When a homeowner in northern Florida looked out at her bird feeders the first weekend in March, she thought she saw a red-headed woodpecker. There was a brown bird nibbling at the wild bird seed with ...

Bilateral gynandromorph green honeycreeper (Chlorophanes spiza) photographed in the wild in Colombia. (Credit: John Murillo.) An “extremely rare” half-female, half-male bird has been caught on film, a ...

Green honeycreepers are found in humid forests from Mexico south towards Brazil and eat fruit, arthropods, and plant nectar. “Many birdwatchers could go their whole lives and not see a bilateral ...

Biologists recently made a "once-in-a-lifetime" discovery of a bird that's male on the right side and female on the left. Researchers captured the bird, a rose-breasted grosbeak (Pheucticus ...

The highly unusual “semi-identical” Australian twins reported last week are the result of a rare event. It’s thought the brother and sister (who have identical genes from their mother but not their ...