Thursday, February 23, 2012

WA Endemic Subspecies - An Annotated List: Part 3: The Kimberley

This is the final of our three part annotated list of WA's endemic subspecies, covering the far north-east of the state: the Kimberley region.

So sudden is the avifaunal shift across the boundary between the Pilbara (Eyrean) and the Kimberley (Torresian) regions, with tropical groups such as lorikeets, parrots, cuckoos, kingfishers and rollers making a dramatic appearance, that Major Whitlock once described it as like “entering a new country” [5]. The rugged mountain ranges and northern plateau of the Kimberley once created a massive Pleistocene drought refuge, separated from similar escarpment country in the Northern Territory by the drier plains of the Bonaparte paleobarrier at the foot of the gulf.  That said, the last of our three lists of WA regional endemics is surprisingly the shortest. Many of these are rock-loving taxa, including the two endemic species, the iconic Black Grasswren, and the eponymous Kimberley Honeyeater, first split from White-lined Honeyeater in C&B 2008 [4]. However the Kimberley also has some very distinctive subspecies, perhaps most notably the yellow-faced race blaauwi of Partridge Pigeon, and one of the ‘Lavender-flanked’ forms of Variegated Fairy-Wren, race rogersi. The Kimberley also has a handful of mangrove-dwelling endemic subspecies, though some of these are shared with the Pilbara. A few ‘almost endemics’ cross the border to the natural barrier of the Victoria River in the NT.

For those that missed it, a handy 2-page checklist of WA endemics can be downloaded here.

Species endemic to WA - Kimberley
Black Grasswren Amytornis housei
Dusky Gerygone Gerygone tenebrosa tenebrosa (also Pilbara G. t. christophori)
Kimberley Honeyeater Meliphaga fordiana

Subspecies endemic to WA - Kimberley
White-quilled Rock Pigeon Petrophassa albipennis albipennis
Partridge Pigeon Geophaps smithii blaauwi
Rainbow Pitta Pitta iris johnstoneiana
Variegated Fairy-wren Malurus lamberti rogersi
Green-backed Gerygone Gerygone chloronotus darwini
Varied Triller Lalage leucomela macrura
Mangrove Golden Whistler Pachycephala melanura melanura (also Pilbara)
White-breasted Whistler Pachycephala lanioides lanoides
Lemon-bellied Flycatcher Microeca flavigaster tormenti
Mangrove Robin Peneonanthe pulverulenta cinereiceps (also Pilbara)
Yellow White-eye Zosterops luteus balstoni (also Pilbara)
Horsfield’s Bushlark Mirafra javanica halli

Subspecies almost endemic to WA - Kimberley (range extends into small part of adjacent NT)
Purple-crowned Fairy-Wren Malurus coronatus coronatus
White-plumed Honeyeater Lichenostomus penicillatus calconi
Silver-backed Butcherbird Cracticus torquatus argenteus
Long-tailed Finch Poephila acuticauta acuticauta

Notes on subspecies
[Except where stated, subspecies descriptions follow Schodde & Mason Directory of Australian Birds [1] (=S&M) for passerines, and Handbook of Australian, New Zealand and Antarctic Birds [2] (=HANZAB) for non-passerines]

White-quilled Rock-Pigeon (race albipennis)
Has a larger white wing patch than NT form boothi, in which the wing patch is greatly reduced or even absent. Johnstone & Storr [3] describes “considerable variation” even within albipennis, with a larger, darker brown form in the north and west Kimberley, and smaller more reddish birds in the east Kimberley, possibly to match local rocks [2].

The WA race of White-quilled Rock-Pigeon, Petrophassa albipennis albipennis, photographed at Chamberlain Gorge, El Questro Station.

Partridge Pigeon (race blaauwi)
Famous for its yellow (not red) facial skin, but Ron Johnstone showed it also lacks a white line (supercilium) above the facial mask, thus is not a simple colour mutant [3].

Spinifex Pigeon (race ferruginea [also Pilbara])
“Red-plumed Pigeon”
Smaller and more richly coloured; underparts are cinnamon brown with a black band, ie. not white.

Rainbow Pitta (race johnstoneiana)
A new Kimberley subspecies defined by S&M [1] on the basis of the larger supercilium, larger wing spot, and blacker belly.

Variegated Fairy-wren (race rogersi)
One of the rock-haunting forms with blue-plumaged females; similar to dulcis of NT Arnhemland escarpments, but the female has a chestnut (not white) face mask.

Purple-crowned Fairy-wren (race coronatus
Reasonably distinct from the Gulf of Carpentaria form macgillvrayi: males have an intense blue tail (not greenish-blue), and females have a buff belly (rather than pure white). This nominate form extends to the Victoria River area of the NT. Vulnerable.

Dusky Gerygone (race tenebrosa [also Pilbara G. t. christophori])
Smaller, darker and greyer compared to the Pilbara form christophori.

Green-backed Gerygone (race darwini)
A generally yellower form with a yellowish cast to the back, more yellow on the flanks, and longer bill.

White-plumed Honeyeater (race calconi)
Very yellow like the Pilbara subspecies carteri, but rather more pale over the back.

Varied Triller (race macrura)
Both this and the NT form rufiventris have obvious dusky barring on the belly; Kimberley birds are distinct for their buff (not cinnamon) belly, and more extensive white tail tips.

Mangrove Golden Whistler (race melanura [also Pilbara])
Narrower black markings in the male, and whiter-bellied in the female. The distribution is unusual; despite the natural barrier of Eighty-Mile Beach this is the same subspecies as in the Pilbara, yet it intergrades with robusta across the northeast Kimberley coast in an area broad enough that the stable hybrids were once considered another subspecies.

White-breasted Whistler (race lanioides)
Larger with a broader chestnut collar than the NT form, which actually does extend into WA in the eastern Kimberley. In contrast to the Mangrove Golden Whistler, the Kimberley subspecies of White-breasted is cleanly isolated by an unusual distribution gap across the north Kimberley coast, attributed to competition from Little Shrike-Thrush.

Silver-backed Butcherbird (race argenteus)
S&M first split the Kimberley and NT ‘Silver-backed’ forms as a distinct species from Grey Butcherbird, arguing they are “at least as close to mentalis as …to torquatus” [1]. Along with the NT’s colletti, the Kimberley form has an obviously silvery back, a white (not grey) ventrum, and lacks white in the lores. Compared to the NT form, argenteus has a partial ‘necklace’ extending from the black hood, and a larger white base to the tail. These morphological differences have since been definitively confirmed by a genetic study (Kearns 2014) which resolved the potentially-troubling mtDNA paraphyly between argenteus and colletti (in Kearns 2011) as due to secondary contact between colletti and the eastern form of Grey Butcherbird, during the last glacial maximum approx 21,000 years ago.

Silver-backed Butcherbird Cracticus argenteus. Photographed along the Pentecost River near El Questro Station township.
Lemon-bellied Flycatcher (race tormenti)
“Kimberley Flycatcher”
A non-yellow form; grey not olive on the dorsum, and white underparts not “lemon-bellied”. This has been regarded as a separate species in the past, but Ron Johnstone showed that it intergrades with adjacent nominate form around the Cambridge Gulf. Nevertheless this was split as a full species adopted by BirdLife International in 2016 (as "Kimberley Flyrobin"), putting this taxon back in the spotlight.

A hybrid Lemon-bellied (Kimberley) Flycatcher photographed near Parry Lagoons, with a small amount of lemon on the ventral flanks. It is in part the presence of this hybrid zone centred on the Cambridge Gulf that some would argue marks  the 'Kimberley Flycatcher' (or 'Flyrobin') as a distinctly-marked subspecies, rather than a full species.
Mangrove Robin (race cinereiceps [also Pilbara])
Smaller and paler, with less black on the lores. Taxonomy at subspecies level is “unresolved”[1].

Yellow White-eye (race balstoni [also Pilbara])
This duller, smaller-billed subspecies is found mostly in the Pilbara, but it also extends a little way around into the Kimberley region.

Horsfield’s Bushlark (race halli)
This pale, greyer-backed, creamier-bellied subspecies is restricted to a relatively small zone spanning Port Hedland to Broome. Birds in the rest of the Kimberley are forresti, which extends into NT and is more tawny in colour.

Long-tailed Finch (race acuticauta)
Has a deep-yellow bill, compared to the red-billed NT form; also slightly paler crown and breast. The two forms apparently intergrade east of the Cambridge Gulf, transitioning around the Victoria River.

The yellow-billed race acuticauta of Long-tailed Finch, photographed at Mornington Station.

[1] Schodde R & Mason I (1999) The Directory of Australian Birds: Passerines. A taxonomic and zoogeographic atlas of the biodiversity of birds of Australia and its territories. CSIRO Publishing.
[2] Marchant S. & Higgins PJ, et al. (eds) (1990-2006). Handbook of Australian, New Zealand and Antarctic Birds. (7 vols). Oxford University Press, Melbourne.
[3] Johnstone RE and Storr GM (1998-2004). Handbook of Western Australian birds (2 vols). Perth, Western Australian Museum.
[4] Christidis L & Boles WE (2008). Systematics and Taxonomy of Australian Birds. CSIRO Publishing, Canberra.
[5] Serventy DL & Whittell HM (1976). Birds of Western Australia. Perth: University of Western Australia Press.

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