In April 2012, we published our revised Western Australian Checklist for Vertebrate Fauna. There were a few questions about some of the details raised on Facebook and Twitter. This reply was written by Ornithology curator, Ron Johnstone in response to some of the birds listings in the checklist:
1. Kimberley Honeyeater. The so called Kimberley Honeyeater Meliphaga fordiana is treated as a subspecies of Meliphaga albilineata in our checklist and in the WA Bird Handbook. there are several reasons for this. Ford (1978) did not separate the Kimberley and Arnhem Land populations whereas Schodde (1989) divided them into two subspecies M.a.fordiana in Kimberley and M.a.albilineata in Arnemland. The characters used to separate these populations were based on a small collection. The WA Museum now has a larger series and the morphological differences between these populations is indeed slight. There is however a difference in territorial song and in proteins. We consider that the morphological and molecular data is evidence for subspecific separation and M.a fordiana is thus listed as a subspecies in the checklist.
2. Western Bowerbird. In the checklist the Western Bowerbird Ptilonorhynchus maculatus guttatus is treated as a a subspecies of the Spotted Bowerbird P.maculatus . It is sometimes treated as a full species and in some checklists placed in the genus Chlamydera .It is a well defined subspecies but bear in mind that the population in central Australia is in many characters intermediate between eastern and western forms.
3. The Western Yellow Robin Eopsaltria australis griseogularis is again listed in our checklist as a subspecies of the Yellow Robin and the footnote mentions that it is sometimes treated as a full species (i.e E.griseogularis). It is a well differentiated subspecies.
4. Gerygone (fusca ) mungi the Desert Gerygone has a different call, and different nest and eggs to that of G.fusca and the checklist has highlighted that difference and the corresponding footnote mentions that mungi is closely related to the Western Gerygone and possibly only a well marked subspecies.
5. Rhipidura (fuliginosa ) albicauda. Again see footnote as closely related to the Grey Fantail and possibly only a well marked subspecies.
6 Rufous Fieldwren Calamanthus campestris. This is an interesting one .The taxonomy of this group is complex and poorly understood. Schodde and Mason (1999) separated the south-western population of WA out as a distinct species the Western Fieldwren Calamanthus montanellus . This treatment was not followed in our WA checklist as there is smooth clinal intergradation between the southern olive and the northern rufous forms ( see the illustration in Vol 2 of WA Handbook) and the calls are identical and birds from very distant populations respond to each others calls. If WA Birdlife can show where to draw the line separating these populations we would be most interested.
7. Western Ground Parrot . While the molecular data shows that this population differs slightly from eastern birds not all eastern populations were studied to look at the degree of difference. I have always treated the WA south-western population as a subspecies and not a particularly well differentiated one. Apparently some eastern and western birds are very similar and Mathews noted that South Australian birds are intermediate. The population in Tasmania leachi is apparently only slightly darker and greener than south-eastern birds but its DNA was apparently not studied. I think that at present it is best to treat eastern and western forms as subspecies.
Overall our checklist is the only one available in Australia that deals with subspecies and is regularly upgraded. While molecular data adds a great deal to our knowledge of relationships incomplete linage sorting appears to be widespread in Australian birds and the two white-tailed black cockatoos for example have identical DNA but are clearly very distinct species.