ID Feature: Corellas

Corellas in the south-west (particularly the Perth area) must be some of the most commonly misidentified birds in WA, particularly by visiting birders. Indeed a quick Google Image Search for Western Corella will turn up photos of all three species labelled as Western. A large part of the problem is caused by confusion over the distribution of the three corella species in the south-west; many field guides do not show introduced populations of Little and (Eastern) Long-billed Corellas, and/or show Western Corella as regularly occurring in Perth. Even the original Thomas & Thomas’ Complete Guide to Finding the Birds of Australia (widely regarded as THE where-to-find guide for Australia) lists Western Corella as a key species at Lake Monger! Fortunately, this has been corrected in the recently published new edition. The reality is that the vast majority of corellas in the Perth metropolitan area are Little or Long-billed Corellas, with very few Western Corellas occurring.



Western Corellas of the northern race derbyi at New Norcia. Note the long bill, relatively long crest (though not fully extended), and strong red lores not extending over eye.

ID Feature: Knots

Following on from one of our previous ID features on Pectoral Sandpiper identification (cf. Sharp-tailed Sandpiper), we now discuss the separation of another tricky wader pair; the two knot species, Great Knot (Calidris tenuirostris) and Red Knot (C. canutus). Both species are regular visitors to much of the Western Australian coast, with very large numbers occurring in the north at locations like Roebuck Bay, near Broome. Identification of the two species in breeding plumage is trivial (providing you’ve correctly identified the bird as a knot), but with the exception of northern areas early and late in the wader season, knots are not commonly encountered in breeding plumage in Western Australia.

Red Knot in breeding plumage (right), easily identifiable from Great Knot by extensive red on face and underparts.

Great Knot moulting out of breeding plumage, easily identified from Red Knot by extensive black breast markings and lack of red colouration on underparts.

Identification of birds not in breeding plumage can be more problematic, and these plumages are the most commonly encountered in WA, particularly in the south. The following features are useful for separating the two species in non-breeding plumage. Structural features mentioned below, like bill length, are still applicable in breeding plumage, but plumage features aren’t. Several plumage features are also applicable to juvenile plumage, generally mention will be made of differences. As always, there can be significant individual variation in many of the features mentioned here, so we advise observers to use a combination of features to confirm identity.

Great (left) and Red (right) Knot in non-breeding plumages, showing similarities and differences. Identification is generally easier in situations where the two species can be compared side by side. See end of Key Features section for an annotated version. 

ID Feature: White-tailed Black-Cockatoos

Although recognised as distinct forms as long ago as 1933 (by none other than ornithologist Ivan Carnaby), Carnaby's (Calyptorhynchus latirostris) and Baudin's (C. baudinii) Black Cockatoos were only officially split by the first Christidis & Boles checklist in 1994 [1]. They are typically described in field guides as 'identical except for bill length', which can be unhelpful for birders who can't get a decent look at the upper mandible. We hope the following information is more useful!

Bill Length (but don't forget width!)
This is the obvious and defining difference between the two species, and reflects a difference in feeding habits. Baudin's use their very long mandible tips to carefully extract seeds from woody fruits (e.g. marri gumnuts), leaving little damage on the nut. Carnaby's tend to much more destructive and will chew the rim off marri nuts to access the seeds.

A male Baudin's Black-Cockatoo carefully hooks the seeds out of a marri nut. Note the brownish tinge to plumage (see General Description below).

ID Feature: Dovetailing

Introducing a uniquely Western Australian birding challenge: the slightly obscure, but not entirely frivolous sport of differentiating Spotted and Laughing Doves solely by their tails!

While these species are usually easily separated by differences in size, colour, and neck markings, it is not uncommon to flush a dove and see only its rear end before it disappears. Furthermore, immature Spotted Doves are smaller, paler, and lack the black neck patch, so are less easily differentiated from Laughing on brief views.


A local Spotted Dove (Streptopelia chinensis) with plumage characteristics of the Indo-Malayan subspecies tigrina, including dark streaking on the wing feathers, light grey lesser coverts on the carpus, and off-white undertail coverts. Most Perth birds lack the latter two features. A CSIRO study [1] found that most Perth birds have dark streaking but browner wing and undertail coverts and are thus an ambiguous mixture of introduced subspecies tigrina and chinensis



Compared to the generally browner Spotted Dove, Laughing Doves (Streptopelia senegalensis) show rich coppery-pinks tones on the body, and more blueish slate-grey wings and rump

 

ID Feature - Pectoral Sandpipers

Pectoral Sandpipers at Lake McLarty.

For our first 'real' post, we thought we'd start with an ID feature from one of the easier bird groups - the waders! Pectoral Sandpipers are being reported more frequently than ever before in the south-west and this summer in particular has seen 'Pecs' turning up at an almost unprecedented number of wetlands.

The primary ID pitfall for Pectoral Sandpiper is Sharp-tailed Sandpiper, which is very similar in appearance. Moreover, in the south-west, Pectoral Sandpipers are typically found in small numbers within Sharp-tailed Sandpiper flocks, which often means some searching is required to locate the Pectorals. However, this also means that it is usually possible to compare the two species side-by-side if you do find a Pec, which can be useful.