Western Australian Bird Notes

Western Australian Bird Notes Quarterly Newsletter of Birds Australia-WA Group (a division of Royal Australasian Ornithologists Union) I I IDENTIFYING CORELLAS IN WESTERN AUSTRALIA I! Introduction species, and at all but Lake Manning single Corellas have been seen around Perth's suburbs since the species flocks of about early 1960s. Although the southern subspecies of the 100 birds have been endemic south-western species, the Western (Western reported. There is also Long-billed) Corella, Cacatua pastinator, used to occur at least one flock of from the south coast to the Swan kver and Northam it had about ten or twelve gone from this area by the turn of the century. Whatever Long-billed Corellas the species, all corellas seen around Perth since the 1960s being seen around are almost certainly derived from aviary escapees. Most of the well known flocks around Perth, Head of Little Corella such as around Lake Monger and Subiaco and ,/ / - ./ '-://w;.> ,:, around Guildford, are mainly Little Corellas, :. , -z//4i:r: . '"&.,. Cacatua sanguinea. It has been recognised for B :$..., Lake Joondalup in the northern some time that these flocks contain small numbers j' suburb of Wameroo. 6,. of one or more of the Western Corella and the , $,, G. Given their introduced status, eastern Australian Long-billed Corella, Cacatua $j there is considerable interest in tenuirostris (see accompanying article in looking at the populations of : .\. , , .I Members' Contributions). _ . "c'. corellas around Perth and ,, > However, in recent months reports have been A . -- "-.re determining whether one or more received of corellas in the southern suburbs; along of the species is expanding, and if the Canning River from Shelley/Riverton/ Head of Western Corella so what the consequences might be Ferndale to in the longer term. In another Kelmscott, along the article in this issue we and Clive lower Swan River Nealon discuss the corellas around from East Fremantle Perth in more detail, and seek assistance in clarifying the and Point Walter to status of the three species. To help in this process, this the South Perth article outlines the key features of each species and how to foreshore and at identlfy them in the field. The descriptions should be used Manning Lake in : % with the associated illustrations. Hamilton Hill south '" Descriptions of Fremantle. It All three species and five subspecies of corellas found in appears that many of Western Australia are medium sized white cockatoos, these birds south of sometimes dirt-stained on the belly, with short crests, the Swan are Long- bluey grey patches of skin around the eye, brown irises and Corellas, that is liead of Long-billed Corella yellow under the wings and tail. At species level they can, the eastern Australian Drawings by Judy Bl~fh with careful observation, be clearly separated by the length and shape of the bill and the amount of pink or orange- the northern subspecies. The upper mandible is heavily red around the face and upper body. It is much easier if notched and has an obviously extended tip, although this adult birds are present because the features listed above is neither as long nor as slender as that of the Long-billed on which the three species can be separated are less Corella. In addition to regional differences in the size and marked in immaturebirds, It is probably not worth trying shape of the bill, these features become more typical of the to separate the subspecies of either Little or Western 'pecies with increasing maturity. Corellas by field observation. The area of orange-red between the eye and bill is both It is quite possible that hybridisation between aviary larger and brighter than in the Little Corella, but still does bred birds once they are in the wild may be more likely "Ot usually extend beyond the eye Or across the top of the than between the populations of two species that have bill. The orange-pink colour of the bases of feathers come together more or less naturally. Thus, the extends from the head and neck to the breast and belly. A possibility of birds around Perth being hybrids between small reddish band, rarely more than a broad line a few any two of the three introduced species should be borne long, may be On the Upperbreast. in mind when attempting to identlfy particular birds. Although the Western Corella has a longer bill than the Little Corella it is readily separated in the field from Little Corella (Cacatua sunguinea) adult eastern Long-billed Corellas, the latter having much The Little Corella is the smallest, shortest billed and more red around the face and throat. However, one has to plainest of the seen around The is look carefully to separate the Western Corella from the 'chunky', any of the upper Little, particularly in the northem agricultural area where The length the ranges from 28 their ranges are most likely to overlap and where the 36 mm, and the upper and lower fit Western Core]]a's bill is shorter than in the southem together neatly with little gap visible when closed. The It is very difficult to separate the two bill is generally much shorter than in either of the two subspeciesof the Corella in the field, other species, although there is a slight overlap between large Little Corellas and small females of the northern (Eastern) Long-billed Corella (Cacatua subspecies of the Western Corella. The Little Corella and tenuirostris) the northern subspecies of the Western Corella do This species is characterised by a very long upper overlap in range in the midwest, and may both occur in mandible, from 39 to 52 mm long, with the elongated tip Perth, so colour pattern and shape of slender and laterally compressed. the bill are needed in identifying Because the notch in the upper mandible. corellas in those areas. into which the lower mandible fits, is The face of Little Corellas has a comparatively shallow, the bill never quite narrow band of dull orangelpink appears fully closed. The resulting between the bill and the eye (the 'uTM1On conspicuous gap between upper and lores). This band is rarely as wide as lower mandibles gives an effect of each the base of the bill and never reaches bird having a permanent smile (see Fig. across the top of the bill or behind the 2). The whole face is bright orange-red. eye. The bases of feathers around the including above the bill and a variably head and neck are pale orangelpink, sized triangle behind the eye, with small and this may be visible when the T.*uI~-~~** reddish patches often visible further back feathers are ruffled. along the sides of the head. In addition. Two subspecies of Little Corella every bird has a bright red 'half- occur in Western Australia: C. necklace', made up of sometimes sanguinea sanguinea is essentially a overlapping lozenge-shaped spots or bird of the Kimberley and other parts splashes, arranged horizontally, between of northern Australia, while *A""'"eA the throat and upper breast. The necklace C. sanguinea westralensis is largely a is about eight to ten centimetres long and north-western form, now occurring two to three centimetres wide in the around the lower Murchison and Figure 2: Bill in centre. It tapers unevenly towards a point at each side of the neck, The coloured Geraldton in the Midwest region as from Ford well and apparently expanding into bases of feathers occur on the head. neck. the central wheatbelt. Both subspecies shoulders, breast and belly. and are may occur in flocks of introduced birds around Perth, usually brighter and more obvious than on either of the although westralensis is the most common. two other species. With the above guidelines, a pair of binoculars and a Western (Western COrella (Cacatua little experience all BAWAG members should have little pastinator) difficulty in identifying each of the three species in the The Western is On average One Or two field. From that point, we should as a group be able to gain centimetres longer than the Little Corella, with a longer a much more accuratepicture of the distribution and status bill and more orange-red colour visible around the face of the corellasaround Perth. and throat. Bill length varies between 45 and 52 mm in John Blyth and Ron Johnstone the southern subspecies and between 33 and 49 mm in Western Australian Bird Notes, vol 86 June 1998 should be accompanied by a description of what was actually seen and reasons for the identification. Note that FERAL CORELLA COUNT a statement to the effect that what was seen fitted a description in a field guide is a statement about what is in 28June1998 a field guide, and does not tell the editors what you actually saw. Providing extra details also assists the Starting 3:30 pm editors to provide extra information to readers. Would you like to help us gain a better SOUTH-WEST (Shark Bay to Cape Arid) understanding of the numbers and status of Malleefowl - 1, 9/97, Kularin Dam, c. 24 km ESE of the three species of corellas that have been Burakin (Mukinbudin) - BL introduced around Perth's suburbs ? (see Freckled Duck - 2, 9110197, Little Darkan Swamp (York) JS, HS, TS 1, 13/4/98, Lake Monger (Perth) articles elsewhere in this issue). - * - JB * 7, 3/4/98, Lake Yangebup (Cockburn) - TD,MxB * If you know of a place that you regularly or 3, 12/4/98, Lake Wheatfield (Esperance) - JC, DC often see corellas, we invite you to take part in Australasian Shoveler - 650+, 13/4/98, Lake Monger an organised count at as many places as (Perth) - JB (high number for ths site) possible throughout the metropolitan area, on Great Crested Grebe - adult plus 2 juvs, 28/2/98, June 28, beginning at 3:30 pm and going until lake in Burswood golfcourse (Perth) - MS 530pm.

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