The White-throated Sparrow, a seemingly ordinary backyard bird, actually has four unique personalities based on its color morphs. Black and white striped birds are more aggressive, while tan-striped birds are more nurturing. Mated pairs almost always consist of one bird of each color morph. These differences are based on variations in behavior, defense of territory, and parenting styles. Research shows that the color morphs are linked to specific chromosomes and genetic traits, creating a “supergene” that controls both color patterns and behaviors. This unique arrangement makes the White-throated Sparrow one of a kind in the bird world, with four distinct sexes.
https://www.audubon.org/news/the-fascinating-and-complicated-sex-lives-white-throated-sparrows