Saturday, December 24, 2011

South-west Endemics Part 2: White-breasted Robin

The White-breasted Robin (Eopsaltria georgiana) is a characteristic resident of tangled gullies and thick understorey in the karri and jarrah forests of south-west WA, though there is also a lesser-known relict population in coastal gully thickets north of Perth. “A quietly garbed but attractive bird” was Serventy and Whittell’s description [1], capturing surprise that a grey and white robin should be so much more striking than a plumage description would make it sound.

White-breasted Robin Eopsaltria georgiana

“Peculiar” was Leach’s more prosaic assessment [2]. Taxonomy of the White-breasted Robin has been surprisingly controversial, given that to superficial appearances it seems a typical (if colourless) Eopsaltria robin. It shares many mannerisms with the Eastern and Western Yellow Robins, such as the habit of clinging sideways to low trunks and branches, motionless except for occasional flicking of the tail and wings. Like them it is initially shy but hopelessly inquisitive, and cannot resist checking you out if you sit still for a moment. Indeed it is so similar to the Yellow Robins that this complex has long been considered a classic example of speciation by double invasion, with successive waves into the south-west forests evolving to lose all (White-breasted Robin) or half (Western Yellow Robin) of an originally fully yellow breast (Eastern Yellow Robin).

However it has sufficient differences from the Yellow Robins, particularly its eggs, to persistently trouble taxonomists. Campbell first removed it from Eopsaltria to Amaurodryas (now Melanodryas) based on a perceived “oological” association with the Dusky Robin of Tasmania; Mathews lumped it instead with Mangrove Robin in the genus Quoyornis, where it remained isolated for some time after Mangrove Robin was split off to yet another monospecific genus Peneonanthe [2]. However a 2009 molecular phylogenetic study [3] reported the unexpected finding that the White-breasted Robin may instead be most closely related to the ‘other’ yellow robins - the two Tregellasia robins (the White-faced and Pale Yellow Robin of north-eastern rainforests).
UPDATE: Christidis et al 2011 [6] confimed this unexpected paraphyletic status of Eopsaltria and recommended that White-breasted Robin return to the genus Quoyornis.

Monday, December 5, 2011

3 People, 50 Hours, 4,474km, One Bird - Eurasian Hoopoe near Broome

In early November this year, the Australian twitching community went into overdrive with news that a Eurasian Hoopoe (Upupa epops) had turned up near Broome. Eurasian Hoopoes occur widely across Europe and Asia. The Broome bird has been identified as the strongly migratory race saturata, which breeds mostly in east Asia (Japan, Siberia, South China etc.) and migrates south to winter, making it the most likely candidate for vagrancy to Australia. Nonetheless, most Aussie twitchers would probably admit that the species had not figured highly on their list of likely new birds for Australia.

Eurasian Hoopoe at Roebuck Roadhouse near Broome.

The bird was found on the 10th November hanging around near the Roebuck Roadhouse, 30km out of Broome, by Kim Onton, Chris Hassell and Marten Hulzebosch. Being a first record for Australia, and a particularly charismatic species to boot, it was no surprise that news of the sighting sent twitchers into something of a frenzy, as many raced to work out the feasibility of a mad dash to see the bird. Fortunately for those that have made the trip, the bird has generally remained in situ since the initial sighting (still present Saturday 3rd December), although it hasn't always been easy to locate and a few people dipped several times before connecting.

The Broome Eurasian Hoopoe feeding up!

Thursday, December 1, 2011

Intermediate Morph Soft-plumaged Petrels off Perth

The Soft-plumaged Petrel (Pterodroma mollis) is a common visitor to offshore waters of southern Western Australia, predominantly from late autumn to early spring. Pelagic seabird trips off Perth, run since 1996, have recorded the species on 27 of the 31 trips run (an 87% recording rate). The species has been recorded less commonly on pelagic trips off Albany, run since 2003, having been recorded on five of the nine trips run (a 56% recording rate).

Soft-plumaged Petrel off Perth.

Soft-plumaged Petrels are one of several petrel species to exhibit polymorphism. The pale morph is easily the most commonly occurring variant, but dark morph individuals are also regularly (but rarely) recorded. Intermediate individuals have been recorded, but these are particularly rare. Indeed, Onley & Scofield [1] report only “a few scruffy intermediate specimens … in museum collections” and “no recent records at sea or from breeding grounds”. This assertion is clouded by differences in treatment of intermediate individuals between authors. Shirihai [2] for example appears to include all intermediate morphs, along with the wholly dark morph, under the dark morphs. He describes the dark morph as being “partially (mottled) to wholly dusky-brown/sooty-grey on underparts, with variable breastband, but rest of plumage as pale morph”. Much of the confusion is likely down to the fact that in reality there is not a distinct intermediate morph; rather intermediate birds can fall anywhere on a spectrum between typical pale morph birds and fully dark individuals.

Pale morph Soft-plumaged Petrel off Perth.