Carnaby’s Black-Cockatoo


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Carnaby's Black-Cockatoo

Calyptorhynchus latirostris Scientific name definitions

  • EN Endangered
  • Names (14)
  • Monotypic

Identification

55–60 cm; 580–770 g; culmen 41–46 mm (mean 44·2 mm) . Body plumage dusky black with buff margins to feathers; off-white patch on ear-coverts; tail has subterminal white panels, but central two feathers all black; eye dark brown; feet grey-brown. Sexes similar but peri­ophthalmic skin pinkish red in male 

, dark grey in female 

; bill grey-black in male, bone-coloured in female; female has larger ear patch. Juvenile resembles female; no immature plumage, immatures resembling adults except that males take at least a year to attain adult bill colour.

Systematics History

Closely related to Z. funerea and Z. baudinii. Long considered conspecific with latter, mainly on account of identical plumages , but currently treated as separate because present species’ ecology quite different and bill significantly shorter than that of Z. baudinii; difficulty in field identification, compounded by long history of conspecific treatment, has led to uncertainty regarding limits of range in area of overlap, and to publication of some inaccurate maps.

Exhaustive analysis of all available specimens of taxa in present genus suggested that latirostris was so similar to South Australian Z. funerea that it might perhaps be treated as race of latter. Monotypic.

Subspecies

Monotypic.

Distribution

Inland and coastal SW Australia (from Kalbarri to Esperance), in 300–750-mm rainfall zone; breeds mainly between Three Springs and the Stirling Range and from Cataby to Tone R in W .

Habitat

Sandplain heath or shrubland and eucalypt woodlands, especially of wandoo (Eucalyptus wandoo) and salmon gum (E. salmonophloia), with annual rainfall in range 300–750 mm. Also forages in wetter marri (Corymbia calophylla), karri (Eucalyptus diversicolor) and jarrah (E. marginata) woodland in non-breeding season .

Movement

Once young fledge, all members of family leave nesting area and join a foraging flock that moves  nomadically; inland nesters move to wetter coastal areas , and flocks of several thousand birds may aggregate in coastal pine forests (such behaviour unknown prior to 1930s). These flocks start to disband prior to onset of next breeding season .

Diet and Foraging

Uses short massive bill  to shred cones  of the native Banksia and Dryandra  species and also the introduced Pinus radiata; after shredding, the seeds are eaten. In non-breeding season sometimes forms foraging flocks with C. banksii . Breeding birds, which typically forage within 12 km of nest, also eat the flowers of a wide variety of heathland plants and others, including AllocasuarinaHakeaGrevillea and Corymbia calophylla , as well as insect larvae. Usually feeds in a tree or shrub, but will forage on ground  , as when eating wild geranium (Erodium).

Sounds and Vocal Behavior

Vocalizations differ slightly from Z. baudinii: main call is high-pitched, drawn-out “whee-la”, with second syllable slightly longer than that of baudinii, while alarm call is harsh screech likened to that of Cacatua galerita, and fledged young give constant harsh wheezing calls .

Breeding

Laying Jul–Nov, or Aug–Dec. Pair-bonds  typically permanent, but nest-sites (selected by female) can vary between years . Female, especially, highly territorial and aggressive, thus many potential nest-sites  may remain unoccupied . Nest is bed of woodchips in a large tree-hollow, 2–20 m above the ground, usually with an entrance at least 18 cm in diameter, at least 15 cm deep and widening to 35 cm at the base.

Clutch of 1–2 white  eggs  (mean 1·7–1·8 , first egg larger than second) ; incubation 28–29 days; female alone incubates eggs and broods nestlings, during which time she is fed by male; chick has yellow or white down; after 4–5 weeks, nestling  is left alone while female forages with male, and from then on both members of pair feed nestling; rate of feeding declines during very hot weather and in areas where food is less abundant; fledging at 10–11 weeks. Only rarely do both nestlings survive at a nest, the second to hatch usually dying within 48 hours .

In one study in 1970s, 7% of recorded nesting attempts failed due to unguarded eggs being damaged by Eolophus roseicapilla, which in some areas competes with present species for nest-holes ; elsewhere 71–77% of eggs hatched, although total clutch failure was 27–30%, and fledging rates from egg and hatching stages were just 20–35% and 29–46%, respectively, while the mean number of young produced per nest was 0·34–0·63 . Birds do not breed until four years old and customarily remain with their parents for first year . Oldest known female in wild was 19 years old.

Conservation Status

ENDANGERED. CITES II. Although large numbers still seen around Perth, Western Australia, the proportion of these that are juveniles from recent breeding is not known. Total population estimated at 9000–35,000 birds in 1977, but although thought to number c. 40,000 in 2007, scattered across four subpopulations (northern wheatbelt, upper southern wheatbelt, south-eastern wheatbelt and Esperance coast), conservation status has been recategorized as Endangered (previously regarded as Vulnerable. 

Breeding population now mainly concentrated between Three Springs and the Stirling Range and areas to W (Cataby to Tone Rover). Major concern is that breeding distribution has shrunk by one third in past 30 years (and declines appear to be ongoing according to most recent data), following clearing of native vegetation for wheat farming (in some areas more than 90% has been lost since 1950s)  and extensive fragmentation (and degradation by domestic livestock) of remaining habitat, with productive feeding areas increasingly distant from nesting sites. In many cases, such problems could have been avoided, or potentially resolved, through preservation or restoration of corridors of native vegetation . 

Nest-hollow availability, though not currently limiting, is likely to become so in the future with feral bees and other cockatoos competing successfully for hollows, and it has been suggested that suitable nest-sites in currently extant areas might be virtually non-existent in some areas by the late 21st century, although replanted natural eucalypt woodland might by then offer viable alternatives.

The concern of foresters that they were not able to harvest pine cones for seed in competition with present species was allayed by producing seed cones in special remote seed orchards, where fertile cones mature on young trees not visited by cockatoos; it was also found that sufficient seed could easily be gathered from the ground below where the cockatoos had been feeding and had dropped many partially eaten cones.

 Of present concern is that many pine plantations, on which birds depend in non-breeding season, are reaching maturity and are set for wholesale harvest. Nest-robbing for domestic trade has declined, but damage to nest hollows occurs when birds taken for illegal export. Natural events, such as disease and exceptional climatic events (including heatwaves and hailstorms), have killed significant numbers of birds in recent years.


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