The Department of Environment and Conservation (DEC) is calling for landholders and volunteers to take part in the 2011 Muir's Corella Count in the State's south-west.
DEC regional nature conservation leader Brad Barton said it was the fourth ground survey of the endangered and endemic bird and it aimed to provide accurate estimates of current population size.
"Muir's corella (Cacatua pastinator pastinator) once inhabited most of WA's south-west from the Swan and Avon rivers, south to Albany and Augusta and east to Broomehill and the Stirling and Porongurup ranges," he said.
"They are now found in only one population near Lake Muir, Boyup Brook, Perup River, Frankland and Rocky Gully.
"The information gained from the surveys is used to assist with management decisions regarding these birds."
In the first corella count in 2007, about 9000 birds were counted during the survey of 22 properties by 55 landholders, volunteers, DEC and Southern Forests Landcare staff.
Mr Barton said volunteers needed no previous bird counting experience and all were welcome as the number of properties to be surveyed had expanded over the years.
"The resounding success of previous surveys is thanks to the assistance of the many people who have given their time to take part in the count," he said.
"During the last count in 2009, 57 people, including landholders, volunteers and DEC staff surveyed 38 properties across Manjimup, Cranbrook, Plantagenet, Boyup Brook and Kojonup shires and counted 12,947 birds during the survey.
This year's corella count will be held on Wednesday 9 March between 6pm and 6.30pm. Participants will meet at the Tonebridge Country Club at 4pm and there will be a barbeque afterwards.
Landholders who regularly see large flocks of corellas on their properties and people interested in taking part in the count are asked to contact Julia Wayne on 9771 7910 or by email at Julia.wayne@dec.wa.gov.au.