We’ve heard of same-sex couplings in the animal kingdom, but not transgender birds. Researchers in New Zealand think they may have discovered the first one, however. Known as a bellbird, this little fine feathered friend (about the size of a sparrow) has the DNA of a female, but behaves like a male and exhibits a mix of each sex’s plumage and behavior.

Researchers told the Dominion Post News that the color balance could be due to a shock or incomplete molting process. The bird also tends to behave like males who move “deliberately” to defend food. It also sounds like both a male and female bellbird, with loud calls that are female-sounding, but in a loud pattern most closely associated with males.

The Maori name for the bird is “korimako,” though the researchers are calling this one a “butch bellbird.” It’s the first species that researchers have ever discovered showing a distinct gender mix.

“There’s something we can’t pin down,” conservationist Erin Jeneway told the paper. “We haven’t seen anything like this before.”