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Gender bending bird has NZ scientists scratching their heads

23/10/2012 09:51:08 Riddle of the "butch bellbird"
October 2012. Staff at Zealandia eco-sanctuary have identified a young bellbird (korimako) which DNA tested as female but behaves as if it were male and has a mix of each sex's plumage. Nicknamed the ‘butch bellbird', it is the first species staff have observed displaying such a gender-mix.

Conservation Officer Erin Jeneway was the first to notice the bellbird as part of a monitoring contract funded by the New Zealand Lottery Grants Board.

"There's something we can't pin down" she said. "We haven't seen anything like this before".

Victoria University moult expert Ben Bell was also surprised to hear of the bird's plumage.

"It could be due to a hormonal imbalance or it could be a reaction to shock or an incomplete moult, given the appearance and behaviour any of those would be unusual though".

When the bird was a chick a feather sample was sent to a Massey University testing facility for genetic analysis (as part of standard procedure), with results showing the bird to be female. Now at 18 months old it has the white cheek stripe of a female on one side, but the dark body plumage of a male. When feeding it doesn't flit quickly between flowers like a female, but moves more deliberately, ready to defend an attractive food resource.

The bird's calls have also been mixed. It makes both male calls and the distinctive ‘chup chup' call of the female, though these are far louder and more frequent than is typically observed in females. The call mix is less unusual than the plumage and behaviour.

Erin Jeneway refers to the bird as "her" whereas co-worker Matu Booth refers to it as "him" - both hope to find out who's right if the bird survives and breeds. The bellbird had been seen frequently around the northwest scarp though it often forages in unprotected habitat beyond the fence so is at risk from mammalian pests.

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