In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.
|EPBC Act Listing Status||Listed as Extinct|
|Adopted/Made Recovery Plans|
Federal Register of
Declaration under s178, s181, and s183 of the Environment Protection and Biodiversity Conservation Act 1999 - List of threatened species, List of threatened ecological communities and List of threatening processes (Commonwealth of Australia, 2000) [Legislative Instrument].
List of Migratory Species (13/07/2000) (Commonwealth of Australia, 2000b) [Legislative Instrument].
List of Migratory Species - Amendment to the list of migratory species under section 209 of the Environment Protection and Biodiversity Conservation Act 1999 (26/11/2013) (Commonwealth of Australia, 2013af) [Legislative Instrument].
|Non-statutory Listing Status||
|Scientific name||Turdus poliocephalus poliocephalus |
|Species author||Latham, 1902|
|Distribution map||Species Distribution Map not available for this taxon.|
Scientific name: Turdus poliocephalus poliocephalus.
Common name: Grey-headed Blackbird.
Other names: Norfolk Island Thrush, Norfolk Island Ouzel, Guavabird.
The Grey-headed Blackbird is accepted to be an extinct subspecies of the Island Thrush (Clement & Hathway 2000; Schodde & Mason 1999).
Of the other two Island Thrush subspecies in Australian territories, T. p. erythropleurus (Christmas Island) is listed as Critically Endangered, and T. p. vinitinctus (Lord Howe Island) is Extinct under the EPBC Act 1999.
The Grey-headed Blackbird was probably about 20-25 cm in length (Clement & Hathway 2000; Hermes 1985; Higgins et al. 2006a). It was mainly dark brown to blackish-brown, with a light-brown to greyish-brown head and neck, indistinct light-brown scalloping on the breast, and some fine white streaks on the belly and undertail (Hull 1909; Higgins et al. 2006a; Schodde & Mason 1999). Adult males and adult females were almost identical in appearance (Clement & Hathway 2000), but sub-adult birds were a reddish-brown to chestnut-brown colour, with a dark brown head, buff-brown throat and belly, and some pale buff streaks and spots (Clement & Hathway 2000; Schodde & Mason 1999).
The Grey-headed Blackbird was formerly considered common and widespread on Norfolk Island (Schodde et al. 1983; Smithers & Disney 1969).
At least 48 other subspecies of Island Thrush are found on islands of south-east Asia and the south-west Pacific Ocean (Garnett & Crowley 2000; Hindwood, 1940).
The Grey-headed Blackbird was not recorded during an extensive survey (which included the use of mist nets) of the Norfolk Island's avifauna in 1975 (McKean et al. 1976). Only a single unconfirmed report was made during an island-wide survey of the island's avifauna in 1978 (Schodde et al. 1983). Furthermore, in 1989, no incidental records of the Grey-headed Blackbird were made during an extensive survey of white-eye Zosterops sp. on Norfolk Island (Bell 1990a).
Like the related Vinous-tinted Thrush (T. p. vinitinctus) on Lord Howe Island, the Grey-headed Blackbird might once have occurred in large flocks (Sharland 1929).
The population of the Grey-headed Blackbird probably began to decline in the early 20th century (Bell 1990), although the subspecies remained common until the early 1940s (Schodde et al. 1983). Its numbers declined rapidly thereafter (Bell 1990; Schodde et al. 1983) and, by the late 1960s, it had become rare (Smithers & Disney 1969) and was believed to be approaching extinction (Wakelin 1968). It was last recorded in 1975 (McKean et al. 1976), although unconfirmed reports were made subsequently in 1978 (Schodde et al. 1983) and 1989 (Higgins et al. 2006; McCoy 1989).
Hybridisation with the closely related Common Blackbird (Turdus merula) has been identified as a potential factor in the extinction of the Grey-headed Blackbird (Schodde & Mason 1999; Schodde et al. 1983). There is some evidence to indicate that hybridisation may have occurred as a substantial proportion of the Common Blackbird population has plumage markings similar to those of the Grey-headed Blackbird. An analysis of DNA could be employed to confirm the presence or absence of genes from the Grey-headed Blackbird in the modern Common Blackbird population (Garnett & Crowley 2000).
The Grey-headed Blackbird inhabited native rainforest, and frequented gardens adjacent to large rainforest remnants. The last few records of the Grey-headed Blackbird, prior to its extinction, were made in rainforest-pine associations dominated by the Norfolk Island Pine (Araucaria heterophylla), the Cow Itch
Tree (Lagunaria patersonii), ironwoods, bloodwoods and ferns (de Ravin 1975; Hermes 1985; Smithers & Disney 1969).
The Grey-headed Blackbird bred from August to December (Hull 1909; North 1899), and again from March to May (Hull 1909). This suggests it may have had an extended breeding season, or reared multiple broods in a season, or both (Schodde et al. 1983; Reville 1993). Its clutches consisted of two to four eggs that were typically greenish grey in colour with reddish-brown markings (Hull 1909; North 1899). It built a cup-shaped nest of palm fibre, leaves and grass that was usually situated in the branches of a shrub, sapling or tree, and often in a lemon tree (Citrus limon) (Hull 1909; North 1899). No other information is available on the breeding biology but, based on the extant subspecies, T. p. erythropleurus, on Christmas Island, eggs were probably incubated by the female for a period of around three weeks, and young probably remained in the nest for about three weeks (Gibson-Hill 1947).
The Grey-headed Blackbird fed on the fruit of Psidium guajava (Hull 1909) and foraged on the ground amongst leaf litter (Garnett & Crowley 2000). Based on the extant subspecies, T. p. erythropleurus, on Christmas Island and on the other subspecies of the Island Thrush, it probably also fed on seeds, insects and other invertebrates (Carter 2000b; Clement & Hathway 2000; Gibson-Hill 1947; Gray 1981), and may have foraged in shrubs and fruiting trees (Clement & Hathway 2000; Gibson-Hill 1947; Gray 1981).
No information was recorded on the movements of the Grey-headed Blackbird. However, based on the extant subspecies, T. p. erythropleurus, on Christmas Island (Carter 1994; Gibson-Hill 1947; Stokes 1988), the Grey-headed Blackbird is presumed to have been resident on Norfolk Island.
The Grey-headed Blackbird is said to have been very tame and confiding (Garnett & Crowley 2000; Hull 1909; McCoy 1989). The male could be distinguished from other birds on Norfolk Island by its light-brown to greyish-brown head and neck (Higgins et al. 2006a; McCoy 1989). The female, which had a more brown-coloured head than the male (Clement & Hathway 2000), was more difficult to identify because of its similarity to the Common Blackbird (McCoy 1989). However, both sexes of the Grey-headed Blackbird had a droopy stance compared to the more rigid form of the Common Blackbird. Furthermore, the Grey-headed Blackbird's eye was larger and had a reddish brown colour in contrast to the dark yellow-ringed eye of the common species (McCoy 1989).
The extinction of the Grey-headed Blackbird has been attributed to the combined effects of clearing of native rainforest, competition with the introduced Common Blackbird and Song Thrush (Turdus philomelos), and predation by the Black Rat (Rattus rattus) and the Cat (Felis catus). It is possible that hybridisation with the Common Blackbird may also have been a factor in its extinction (Bell 1990; Robinson 1988; Schodde et al. 1983; Smithers & Disney 1969). However, the fact that the Grey-headed Blackbird remained common on Norfolk Island in the early 1940s, more than 100 years after the introduction of cats, and more than 20 years after the introduction of the Common Blackbird (introduced in 1918) and Song Thrush (introduced in 1913). Its rapid decline, following the introduction of the Black Rat in the early 1940s, suggests that predation by the Black Rat was probably the main cause of its extinction (Bell 1990; Garnett & Crowley 2000; Robinson 1988; Schodde et al. 1983).
No major studies were conducted on the Grey-headed Blackbird before its extinction. Available information on the Australian subspecies of T. policephalus is summarised by Higgins and colleagues (2006a) and The Action Plan for Australian Birds (Garnett & Crowley 2000).
Management documents relevant to the Grey-headed Blackbird are at the start of the profile.
The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.
|Threat Class||Threatening Species||References|
|Agriculture and Aquaculture:Agriculture and Aquaculture:Land clearing, habitat fragmentation and/or habitat degradation||The Action Plan for Australian Birds 2000 (Garnett, S.T. & G.M. Crowley, 2000) [Cwlth Action Plan].|
|Uncategorised:Uncategorised:threats not specified||Turdus poliocephalus poliocephalusin Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006zo) [Internet].|
Bell, B.D. (1990a). The Status and Management of the White-breasted White-eye and Other Birds on Norfolk Island. Report to Australian National Parks and Wildlife Service, Canberra.
Carter, M. (1994). Birds of Australia's Christmas Island. Wingspan. 13:18-21.
Carter, M. (2000b). Christmas Island, Western Australia. Australian Birding Magazine. 6 (3,4):23-24.
Clement, P. & R. Hathway (2000). Thrushes. Christopher Helm, London.
De Ravin, J.A. (1975). The birds of Norfolk Island. Australian Bird Watcher. 6:4-10.
Garnett, S.T. & G.M. Crowley (2000). The Action Plan for Australian Birds 2000. [Online]. Canberra, ACT: Environment Australia and Birds Australia. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/action/birds2000/index.html.
Gibson-Hill, C.A. (1947). Notes on the birds of Christmas Island. Bulletin of the Raffles Museum. 18:87-165.
Gray, H.S. (1981). Christmas Island - Naturally. Author, Geraldton, Western Australia.
Hermes, N. (1985). Birds of Norfolk Island. Wonderland Publications, Norfolk Island.
Higgins, P.J., J.M. Peter & S.J. Cowling, eds. (2006a). Boatbill to Starlings. In: Handbook of Australian, New Zealand and Antarctic Birds. 7. Melbourne: Oxford University Press.
Hindwood, K.A. (1940). The birds of Lord Howe Island. Emu. 40:1-86.
Hull, A.F.B. (1909). The birds of Lord Howe and Norfolk Islands. Proceedings of the Linnean Society of New South Wales. 34:636-693.
McCoy, H. (1989). Sighting of "Guavabird" - Grey-headed Blackbird. Norfolk Nature Notes. 5:307-308.
McKean, J.L., O. Evans & J.H. Lewis (1976). Notes on the birds of Norfolk Island. Notornis. 23:299-301.
North, A.J. (1899). Nests and eggs of birds found breeding on Lord Howe and Norfolk Islands. Australian Museum Catalogue. 12:407-416.
Reville, B.J. (1993). A Visitor's Guide to the Birds of Christmas Island, Indian Ocean. In: second edition. Christmas Island Natural History Association, Christmas Island.
Robinson, D. (1988). Ecology and management of the Scarlet Robin, White-breasted White-eye and Long-billed White-eye on Norfolk Island. Report to Australian National Parks and Wildlife Service, Canberra.
Schodde, R. & I.J. Mason (1999). The Directory of Australian Birds: Passerines. Melbourne, Victoria: CSIRO.
Schodde, R., P. Fullagar & N. Hermes (1983). A review of Norfolk Island birds: past and present. Australian National Parks and Wildlife Service Special Publication. 8.
Sharland, M.S.R. (1929). Land birds of Lord Howe Island. Emu. 29:5-11.
Smithers, C.N. & H.J. Disney (1969). The distribution of terrestrial and freshwater birds on Norfolk Island. Australian Zoologist. 15:127-140.
Stokes, T. (1988). A review of the birds of Christmas Island, Indian Ocean. Australian National Parks and Wildlife Service Occasional Paper.
Wakelin, H. (1968). Some notes on the birds of Norfolk Island. Notornis. 15:156-176.
This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.
Citation: Department of the Environment (2014). Turdus poliocephalus poliocephalus in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Sat, 2 Aug 2014 11:03:35 +1000.