Red- and White-Tailed Cockatoos of Western Australia

On the Swan Coastal Plain area in Western Australia, over 1000 volunteers recently took on the task of counting Carnaby's black cockatoos. Dozens of roosting sites were monitored by the volunteers. The regular count takes in areas from Moore River in the north, east to York and south to Yalgorup.

Western Australia is home to several black cockatoo species. Carnaby's black cockatoo (Calyptorhynchus latirostris) is one of two species of white-tailed black cockatoos. Together with the Forest Red-Tail black cockatoo, these species are not found anywhere else in Australia or the world.

Carnaby's and Baudin's black cockatoos are very similar.

Baudin's black cockatoo is also known as the long-billed black cockatoo (Calyptorhynchus baudinii). It gets its name from Baudin, a French explorer who landed on the south coast of Western Australia. It has white tail panels and white patches on the cheeks. It is a large bird, from 53 to 58 cm long. The grey-black plumage has a narrow off-white edging giving a scalloped effect. Short, erectile feathers from a crest on top of the head and light-coloured feathers cover the ears. The beak is strong and curved, but longer, finer and more tapered on the upper part than that of Carnaby's cockatoo. The fine point on the beak enables the Baudin's to prise open the gumnuts of the marri or redgum tree.

Short-billed black cockatooCredit: Wikimedia

Carnaby's black cockatoo

Baudin's black cockatoo prefers wetter, more heavily-treed areas of the extreme south-west. It is also a pest in the fruit orchards of the region. Some years back a bounty was paid on birds shot in orchards but the wheel has turned full circle and the species are now protected. Orchardists are restricted to protecting their crops using scare tactics and harassment techniques such as gas guns. The effectiveness of such procedures are of limited use. Like the Carnaby's, Baudin's is gregarious. Large, raucous groups travel together to the feeding sites. This species (Baudin's) is listed as vulnerable.

The forest red-tailed black cockatoo (Calyptorhynchus banksii naso) is a subspecies and is endemic to the south-west corner of Western Australia between Perth and Albany. It is regarded as threatened. The genus name means 'hidden beak' - 'calypto' 'hidden' and 'rhynchus' 'beak'. This term comes from the bird's ability to fluff up the feathers round the beak concealing it from view. The bird is a glossy black with a vibrant orange-red stripe towards the end of the tail. When spreading the tail for landing, the red feathers look like brake lights. The head and wing coverts have yellow spots and there are orange-yellow bars on the belly. There are also narrow bands on the undertail coverts. The red-tailed black cockatoo has an integral place in many indigenous dreamtime fables of the indigenous people.

Red-tailed black cockatooCredit: Original uploader was Scarlet23 at en.wikipedia

Red-tailed black cockatoo

Carnaby's is very similar in appearance to the Baudin's but has a shorter, broader beak and a shorter call. It is sometimes known as the short-billed black cockatoo. Seeds of proteaceous (evergreen shrubs) species such as grevilleas, hakeas and banksias make up the major part of the diet although they also eat the seeds from eucalyptus and corymbia species as well as those of sheoak, wattle and grasstrees. The seed pods are normally broken open while the birds are perched in the trees but they also forage on the ground. A group of feeding cockatoos can leave a great collection of nipped-off twigs, small branches and seed pods under a tree.

Part of the survival problem for the Carnaby's cockatoo is the need for two different habitat types. The birds nest in salmon gum or wandoo hollows but feed in adjacent shrubland. If the two are too distant, the birds don't have a very successful breeding pattern. The nesting hollows are generally 2 to 10 metres above the ground and 0.25 to 6 metres deep. Holes of these dimensions are found only in very old trees.

Pairs mate for life and congregate in small flocks during the breeding season, coming together into larger groups when leaving for the feeding areas. The mortality rate is very high

Carnaby's cockatoo was once widespread throughout the southern part of the state. Numbers have dropped since the late 1940s when land clearing, introduced species and illegal poaching have seen numbers slashed by half. The species is now listed as 'rare or likely to be extinct'. When the figures were collated this year, numbers were well down. In 2010, 5,058 birds were counted compared with 3,402 in 2011.

It is alleged that land clearing is the main reason for the latest drop in numbers. Figures from the WA Local Government's Perth Biodiversity Project showed that, between 2001 and 2009, over 6800 hectares of bush was cleared in the metropolitan area. Urban development was responsible for the destruction of huge areas of habitat. Over 8000 hectares of potential habitat around Perth has been zoned urban, urban deferred or industrial. This area is under direct threat of clearing and development.

The Great Cocky Count was a joint venture between the Department of Environment and Conservation and Birds Australia.