Western Corella

Identificazione

Cacatua pastinator is a white cockatoo with the upper wing entirely white and under surface of the wing pale yellow. It has an erect white crest, blue grey eye skin, crimson pink colouring between the eyes and beak, a small pink patch on the throat, and long pointed bill. Cacatua pastinator lacks sexual dimorphism and the sexes are difficult to distinguish. Determination of the sex of Cacatua pastinator cannot be determined on the basis of eye colour or plumage, observations of pairs have revealed that the males are larger than the females and have a deeper alarm call. Cacatua pastinator is a medium-sized stocky cockatoo with broad rounded wings, a short tail, and a crest which is usually flattened. Muir's Corella (Cacatua pastinator pastinator) adults range in length from 43–48 centimetres (17–19 in) and weigh 560–815 grams (19.8–28.7 oz). The northern subspecies, Butler's Corella (Cacatua pastinator butleri), are a smaller bird with adults 40–48 centimetres (16–19 in) in length and weighing up to 700 grams (25 oz). The bill is a dullish grey white, the legs are dark grey and the upper mandible has a long tip. The underparts are often stained or dirty as a result of feeding on the ground and digging.<p>The flesh of the western corella is described as plump and tender, and suitable for stewing.

Tassonomia

Cacatuidae is one of three families of the large and diverse avian order Psittaciformes which consists of 370 species. Cockatoos are distinguished from other parrots by five main morphological features – a crest, lack of "green" dyck-texture in the plumage, yellow natal down, a gall bladder, and bridge temporal fossa<p>The western corella (also known as the western long-billed corella) Cacatua pastinator consists of two geographically isolated sub-species, Butler's corella (Cacatua pastinator butleri) and Muir's corella (Cacatua pastinator pastinator)<p>One of these two isolated populations occurs in the northern wheat-belt region of Southwest Australia, the other, consisting of larger birds occurs in the far south west of Western Australia. The northern Cacatua pastinator butleri consists of generally of smaller birds than the southern Cacatua pastinator pastinator, which indicates that the two populations may have once been connected clinally.<p>The Australian Faunal Directory, citing a classification by Johann Georg Wagler of genus Licmetis, recognises this species within a subgeneric arrangement as Cacatua (Licmetis) pastinator as determined in a revision published in 1987. Two subspecies are recognised, the nominate Cacatua (Licmetis) pastinator pastinator and Cacatua (Licmetis) pastinator derbyi Mathews, 1916. This was published by Gregory Mathews to describe a specimen that was obtained in the northern Wheatbelt region, the labelling recognised as by the collector J. T. Tunney, which was later annotated as "Derby" and presumed by Mathews to refer to Derby, Western Australia. The subspecies name, despite the apparent mislocation, was recognised by Richard Schodde in the Zoological Catalogue of Australia, 1997.<p>The common names include western corella and western long-billed corella. The names in the Noongar language were surveyed and regularised as manatj and manyte for adoption into common usage. Manatj is used to refer to the Western Australian Police, presumed to be an association with the species "noisy and inquisitive" nature.

Nome scientifico

Cacatua pastinator

Autorità

(Gould, 1841)

Ordine

Psittaciformi

Famiglia

Cacatuidi

Genere

Cacatua

Areale e habitat

The two separate populations described as subspecies occur in south-west Western Australia. The population occurring in the northern wheatbelt of south-western Australia consist of 5000–10000 birds while the population in the far south west of Western Australia consists of approximately 1000 birds. The two isolated populations each consist of one of the identified sub species. Butler's corella (Cacatua pastinator butleri) occurs in the northern and central wheatbelt of Western Australia whilst Muir's corella (Cacatua pastinator pastinator) occurs in the very south-west area of Western Australia.<p>Historical records indicate the species was common at the time of colonisation of Western Australia, and continued to be seen in large flocks during the nineteenth century. The absence of records by the early collector John Gilbert's suggests that this corella was abundant and ubiquitous.<p>The habitat of Cacatua pastinator consists of undulating land with low relief (less than 100 m) with more than 90% of native vegetation cleared for farming of wheat and sheep. The remaining woodland and shrub vegetation communities are restricted to small isolated patches and road reserves. Habitat critical to Cacatua pastinator comprises large eucalypts and other trees (either alive or dead) in forested areas or as lone paddock trees and roadside vegetation, preferred tree species are marri (Corymbia calophylla), jarrah (Eucalyptus marginata), moitch (Eucalyptus rudis), yate (Eucalyptus cornuta) and the paperbark, moonah (Melaleuca preissiana).<p>Cacatua pastinator have displayed three phases of movement patterns within the central wheatbelt of Western Australia, these phases are dependent on the age of the birds. Breeding takes place in spring, following fledging of nestlings the family groups join up with immature flocks and move to summer feeding locations, during the following month the young are weaned and the parents move back to the breeding ground during the January – March period, the juveniles do not return until May or June. Although there is some dispersal to other breeding areas, most individuals display attachment to their natal area with some birds being known to return after being absent for up to five years.

Migrazione

Nomade

Comportamento

Comportamento migratorio: Nomade.

Conservazione

Tendenza della popolazione: in aumento.

Tendenza della popolazione

in aumento