Western Corella Cacatua pastinator


1.2k shares
Western Corella
  • LC Least Concern
  • Names (14)
  • Subspecies (2)

Identification

37–45 cm (1); male c. 700 g, female c. 600 g. White  , with medium-length crest  (47–56 mm) and long upper mandible (37–52 mm); concealed bases of the feathers of the head  and neck salmon-red, showing as varying areas of red on face and forehead  ; underwing  washed yellow; bare periophthalmic skin greyish blue; eye dark brown; bill horn-coloured; legs grey. Sexes alike. Separated from C. sanguinea on generally larger size, with longer crest and longer bill; also on different calls. Juvenile as adult, but bill shorter and periophthalmic ring can appear greyer (1); reaches maturity only when 3–5 years old (2). Race derbyi averages shorter bill (42 mm in male, 37 mm in female) than nominate.

Systematics History

Editor’s Note: This article requires further editing work to merge existing content into the appropriate Subspecies sections. Please bear with us while this update takes place.Sometimes considered to include smaller and smaller-billed C. sanguinea, and in the past treated as conspecific with C. tenuirostris; on current evidence, the three (entirely allopatric) forms probably best considered to constitute three separate species. Type specimen of race derbyi previously considered of doubtful origin and locality, but subsequently validated (3); described form butleri (from near Coorow) is synonym of derbyi. Two subspecies recognized.

Subspecies


SUBSPECIES

Cacatua pastinator derbyi Scientific name definitions

Distribution

N wheatbelt of W Western Australia, from around Geraldton S to c. 32º S.


SUBSPECIES

Cacatua pastinator pastinator Scientific name definitions

Distribution

SW Western Australia (centred around Unicup and L Muir).

Distribution

Editor’s Note: Additional distribution information for this taxon can be found in the ‘Subspecies’ article above. In the future we will develop a range-wide distribution article.

Habitat

Grassy, open forest and eucalypt (1) woodland, especially along watercourses (1), and adjacent farmland with large trees (1); also recorded (more occasionally) from mulga and mallee (1).

Movement

Pairs tend to nest in traditional sites and to forage nearby (typically 1·6 km away) (2) while breeding, until fledglings are large enough (when c. 2 weeks old) (2) to accompany parents into the large nomadic foraging flock  (typically 500–700 individuals in N population) (2) that forms throughout summer, autumn and early winter (Nov–Mar, sometimes only mid-Jan) (2), when regularly forage up to 10 km from nest-tree (2) and some N populations may regularly move 150–250 km north-west (2); such flocks may draw families from 50–100 km away. Immatures leave family group before next breeding season, to spend 3–5 years in a nomadic non-breeding flock, which moves over an area of up to 250 km², typically spending 1–2 weeks in a given area, before moving again, and which may range far from their natal areas (2).

Diet and Foraging

Gregarious graminivore, but also takes insects and their larvae. Long upper mandible enables bird to dig up 

© Nicole BouglouanCanarias, Spain 03 Jan 2008

underground storage parts of a variety of native plants, e.g. Drosera, growing in woodland; this food source became rare following European settlement and was replaced by cereal grains (particularly Avena sativa (4), Triticum aestivum (4), rice and millet) (1), native grasses (e.g. Poa annua) (4) and exotic weeds, e.g. Emex australis (mainly in N of distribution) (1) and Romulea rosea (especially in S of range) (1); the latter has a bulb that corellas dig up when the soil is moist. Birds also dig up germinating cereals and eat grain both from standing crops and from the ground. Sometimes forages in association with Eolophus roseicapilla, and regularly visits artificial waterholes to drink (1).

Sounds and Vocal Behavior

Considered to be very similar to that of C. sanguinea, giving a trisyllabic chuckling, various soft notes with a quavering quality, and a series of harsh shrieks  in alarm (1).

Breeding

Laying Jul–Oct. Pair-bond maintained throughout the year. Nest is a bed of woodchips, in tree hollow in native eucalypts, mainly Eucalyptus salmonophloia in N and E. calophylla in S, and typically in mature to dying trees with a very open canopy (5). Usually 2–3 eggs  (range 1–4, mean 2·7 in one study) (6); incubation 22–26 days by both parents, and both feed the nestlings; hatching asynchronous, and brood reduction by death of smallest nestling occurs frequently in the first two weeks of nestling life; chick has sparse pale yellow down; young birds leave nest when c. 60 days old (52–68), and stay in contact with parents until at least autumn (Apr–May) of their first year, i.e. almost to start of following nesting season. On average over several years, pairs raised 0·8 nestlings to independence each year, with hatching success and fertility rates of 67% and 77%, respectively, 8% of clutches failing completely, and overall productivity of 58% from egg stage, rising to 84% from those eggs that hatched (6).

Conservation Status

Conservation status on BirdlifeLC Least Concern

Not globally threatened. CITES II. Previously considered Near Threatened. Population of nominate pastinator may be increasing, but at present numbers c. 1000–1500 birds (was considered almost extinct in early 1940s) (1), and race is classified as Endangered (7); this is especially pertinent as most members of the population gather to feed on localized oat crops in just five or six areas (1). Race derbyi appears to have survived a long period (1860–1960) of harassment from farmers, who poisoned them, and shot them as agricultural pests; this population is now thriving and expanding, due both to protective legislation (although a few are still shot pr poisoned illegally) (7) and expansion of agriculture since 1950s (1). Dependence on old to very old trees for nesting may limit species’ breeding capacity in near future (5), although the extent to which current forest practices amplify this problem (and the age of the trees that C. pastinator requires for nesting) have been strongly disputed (8).


Like it? Share with your friends!

1.2k shares