Survey finds half as many red-tailed black cockatoos this year. Image by Lip Kee YapSightings of the endangered red-tailed black cockatoo have dropped by more than half in the south-east of South Australia and western Victoria.
Annual research on the numbers has just ended and this year's sightings have dipped to 680 birds from about 1,400 last year.
The decline has the volunteers from the south-east cockatoo recovery project scratching their heads.
One of the group Bronwyn Perryman says 159 volunteers checked 2,800 square kilometres.
"This year we've only had two reasonable size flocks located up in western Victoria, so most of the other birds counted were in pretty small numbers," she said.