NSW Scientific Committee – final determination
The Scientific Committee has found that:
1. The Red-lored Whistler Pachycephala rufogularis Gould, 1841 is a small (21 cm) grey-brown songbird with a rusty orange face, throat and belly (separated by a grey breast-band), and red eyes. The female is much duller, almost lacking the orange colouration. The Red-lored Whistler is very similar to the respective sexes of Gilbert’s Whistler, but the orange is much more extensive on the face and underparts.
2. The Red-lored Whistler occurs in mature mallee or advanced regrowth (especially between 16 and 35 years post-fire, but rarely in much older stands, e.g. 50+ years), with a shrub layer (e.g. Broombush in some areas) and a spinifex (Triodia scariosa) ground layer. Historically there were two main populations in NSW: one at Round Hill/Nombinnie Nature Reserves near Hillston, with an isolate at Pulletop Nature Reserve near Griffith, and another population in the Scotia Mallee adjoining South Australia and north-west Victoria. The whistler was recorded in the Scotia Mallee in the first national bird atlas in 1977-81 (at low reporting rates: Blakers et al. 1984), but not in the second in 1998-2002 (Barrett et al. 2003). Recent intensive surveys in Scotia, Tarawi Nature Reserve, Mallee Cliffs National Park, Petro and Lethero stations and private land in the area failed to find the species (S. Watson pers. comm. July 2008). Thus, there are now only one or perhaps two populations in NSW.
3. Because of the whistler’s cryptic behaviour and preference for dense habitat, the number of birds in NSW is difficult to quantify accurately, yet the known population size is extremely low. Annual bird reports over the past 15 years (1989-2004) have reported mostly single individuals, occasionally two or up to six, at Round Hill Nature Reserve and/or Nombinnie Nature Reserve and State Conservation Area. In seven of these years there were no birds reported (NSW Field Ornithologists Club data). In 2001-2002, intensive searches by NSW National Parks and Wildlife Service made 27 observations in four clusters. The limited number of subsequent records may be due to low survey effort. Trends in the population are poorly known but are thought to have declined in the past decade (D. Egan in litt. November 2008).
4. The Pulletop subpopulation is extinct, and there have been no published reports of the south-west NSW mallee population for over two decades (Higgins and Peter 2003). The whistler’s habitat can be degraded by frequent fire and mallee remnants on grazing land are likely to be in suboptimal condition. For example, the Cobar Peneplain Bioregion has a landscape stress rating of 3, and the Murray-Darling Depression Bioregion a stress rating of 4, out of 6, although these regions are only 30% and 6% cleared, respectively (Barrett et al. 2007). Globally, the species’ range has contracted and breeding populations have declined, with losses of subpopulations from small habitat remnants (Garnett and Crowley 2000; Higgins and Peter 2003). Declines in Victoria are continuing, with contraction to the larger reserves. Losses from some reserves (Wathe, 5000 ha; Bronzewing, 13,000 ha and Annuello, 20,000 ha) over the last 2-3 decades suggest that reserves of this scale are insufficient for long-term persistence (R. Clarke pers. comm. July 2008). The whistler appears to be now extinct in Hattah-Kulkyne National Park, which is contiguous with the 600,000 ha Murray-Sunset National Park. A large portion of its core range in South Australia was burnt in 2006, and it appears to be extinct in Ngarkat Conservation Park (SA) owing to a combination of wildfire and drought (R. Clarke pers. comm. July 2008). These trends suggest that a decline is occurring or will occur in similar NSW habitat.
5. Historically, the main threat was habitat clearing. Threats to remaining habitat include frequent fires over large areas (versus a mosaic of age classes) and overgrazing by livestock. Predation by cats and foxes may influence viability of the small populations. ‘Clearing of native vegetation’, ‘High frequency fire resulting in the disruption of life cycle processes in plants and animals and loss of vegetation structure and composition’, ‘Predation by the Feral Cat Felis catus (Linnaeus, 1758),’ ‘Predation by the European Red Fox Vulpes vulpes (Linnaeus, 1758),’ and ‘Competition and habitat degradation by feral goats, Capra hircus Linnaeus, 1758’ are listed as Key Threatening Processes under the NSW Threatened Species Conservation Act 1995.
6. The Red-lored Whistler is listed as Threatened in Victoria (Flora & Fauna Guarantee Act; Endangered on the Advisory List), and Rare in South Australia. The species is considered globally Near Threatened (Garnett and Crowley 2000).
7. Red-lored Whistler Pachycephala rufogularis Gould, 1841 is eligible to be listed as a Critically Endangered species as, in the opinion of the Scientific Committee, it is facing an extremely high risk of extinction in New South Wales in the immediate future as determined in accordance with the following criteria as prescribed by the Threatened Species Conservation Regulation 2002:
Clause 16
The estimated total number of mature individuals of the species is:
(a) very low,
and:
(e) the following conditions apply:
(i) the population or habitat is observed or inferred to be severely fragmented
(ii) all or nearly all mature individuals are observed or inferred to occur within a small number of populations or locations
Clause 17
The total number of mature individuals of the species is observed, estimated or inferred to be:
(a) extremely low.
Dr Richard Major
Chairperson
Scientific Committee
Proposed Gazettal date: 31/07/09
Exhibition period: 31/07/09 - 25/09/09
References:
Barrett G, Silcocks A, Barry S, Cunningham R, Poulter R (2003) ‘The new atlas of Australian birds.’ (RAOU: Melbourne)
Barrett GW, Silcocks AF, Cunningham R, Oliver DL, Weston MA, Baker J (2007) Comparison of atlas data to determine the conservation status of bird species in New South Wales, with an emphasis on woodland-dependent species. Australian Zoologist 34, 37-77.
Blakers M, Davies SJJF, Reilly PN (1984) ‘The atlas of Australian birds.’ Melbourne University Press: Melbourne)
Garnett S, Crowley G (Eds) (2000) ‘The action plan for Australian birds 2000.’ (Environment Australia: Canberra)
Higgins PJ, Peter JM (Eds) (2003) ‘Handbook of Australian, New Zealand and Antarctic Birds (Vol. 6).’ (Oxford University Press: Melbourne)
NSW Field Ornithologists Club (1988-2007) NSW annual bird reports, published annually in Australian Birds.