Staff at an eco-sanctuary in New Zealand have identified a transgender bellbird with female DNA, male behaviour and plumage of both sexes.

Conservation officer Erin Jeneway at Zealandia eco-sanctuary outside Wellington was the first to spot the trans bird.

‘There’s something we can’t pin down. We haven’t seen anything like this before,’ Jeneway said to The Dominion Post.

Bellbirds are sparrow-sized and named after their melodic song. The trans bird makes male and female mating calls but his female call is louder and more frequent than is usual.

Although a DNA test showed the bird as female, his feeding habits are more male as he moves in a defensive way to protect attractive sources of nectar. He has the dark feathers of a male, but also a white stripe of the female on one cheek.

Ben Bell, an ornithologist from Wellington’s Victoria University, said the bird’s transgender characteristics were ‘unusual’ and ‘could be due to a hormonal imbalance’.

Staff at Zealandia have nicknamed the bird ‘butch bellbird’.