NSW Scientific Committee - final determination
The Scientific Committee has found that:
1. The Varied Sittella Daphoenositta chrysoptera (Latham 1802) is a small (10 cm) songbird with a sharp, slightly upturned bill, short tail, barred undertail, and yellow eyes and feet. In flight the orange wing-bar and white rump are prominent. In NSW most individuals have a grey head and are streaked with dark brown, but in the extreme north-east they have a white head, and in the extreme south-west a black cap. Varied Sittellas are much more active and acrobatic among branches than the larger treecreepers.
2. The Varied Sittella is sedentary and inhabits most of mainland Australia except the treeless deserts and open grasslands, with a nearly continuous distribution in NSW from the coast to the far west (Higgins and Peter 2002; Barrett et al. 2003). It inhabits eucalypt forests and woodlands, especially rough-barked species and mature smooth-barked gums with dead branches, mallee and Acacia woodland. The Varied Sittella feeds on arthropods gleaned from crevices in rough or decorticating bark, dead branches, standing dead trees, and from small branches and twigs in the tree canopy. It builds a cup-shaped nest of plant fibres and cobwebs in an upright tree fork high in the living tree canopy, and often re-uses the same fork or tree in successive years. Generation length is estimated as 5 years (Debus and Soderquist 2008).
3. The Varied Sittella's population size in NSW is uncertain but is believed to have undergone a moderate reduction in population size on the basis of comparative atlas surveys over the past several decades. The species was reported in 69 one-degree grids in NSW in the first national bird atlas in 1977-81 at mostly moderate to high reporting rates (Blakers et al. 1984). It was recorded in 63 one-degree grids in the second national bird atlas in 1998-2002 at mostly low reporting rates, and with gaps in its distribution coinciding with heavily cleared bioregions (Barrett et al. 2003). The index of abundance (reporting rate) for this species declined significantly by 44% in NSW in the 20 years between the two atlases, but with no significant change nationally (Barrett et al. 2003, 2007). Assuming a linear decline this is equivalent to a state wide decline of 35% over 3 generations (15 years) the time frame recommended by IUCN (2008) for estimating population change. The Varied Sittella was not less likely to be detected in Atlas 2 versus Atlas 1 due to the different survey methods (Barrett et al. 2003) and therefore comparison of the two atlases is unlikely to be significantly affected by survey bias.
4. The apparent decline has been attributed to declining habitat cover and quality (e.g. Watson et al. 2003). The sedentary nature of the Varied Sittella makes cleared agricultural land a potential barrier to movement. Survival and population viability are sensitive to habitat isolation, reduced patch size and habitat simplification, including reductions in tree species diversity, tree canopy cover, shrub cover, ground cover, logs, fallen branches and litter (Watson et al. 2001; Seddon et al. 2003). The Varied Sittella is also adversely affected by the dominance of Noisy Miners Manorina melanocephala in woodland patches (Olsen et al. 2005). Current threats include habitat degradation through small-scale clearing for fencelines and road verges, rural tree decline, loss of paddock trees and connectivity, 'tidying up' on farms, and firewood collection. 'Clearing of native vegetation', 'Loss of hollow-bearing trees', and 'Removal of dead wood and dead trees' are listed as Key Threatening Processes in NSW under the Threatened Species Conservation Act 1995.
5. The Varied Sittella is listed as a Vulnerable species in the Australian Capital Territory.
6. The Varied Sittella Daphoenositta chrysoptera (Latham 1802) is not eligible to be listed as an Endangered or Critically Endangered species.
7. The Varied Sittella Daphoenositta chrysoptera (Latham 1802) is eligible to be listed as a Vulnerable species as, in the opinion of the Scientific Committee, it is facing a high risk of extinction in New South Wales in the medium-term future as determined in accordance with the following criteria as prescribed by the Threatened Species Conservation Regulation 2002:
The species has undergone, is observed, estimated, inferred or reasonably suspected to have undergone or is likely to undergo within a time frame appropriate to the life cycle and habitat characteristics of the taxon:
(c) a moderate reduction in population size,
(d) an index of abundance appropriate to the taxon.
Dr Richard Major
Proposed Gazettal date: 12/02/10
Exhibition period: 12/02/10 – 09/04/10
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)
Debus SJS, Soderquist TR (2008) Report for Review of Species for the NSW Scientific Committee: Varied Sittella Daphoenositta chrysoptera.
Higgins PJ, Peter JM, (Eds) (2002) 'Handbook of Australian, New Zealand and Antarctic birds (vol. 6).' (Oxford University Press: Melbourne)
IUCN (2008) 'Guidelines for using the IUCN Red List Categories and Criteria. Version 7.0.' (Standards and Petitions Working Group of the IUCN Species Survival Commission Biodiversity Assessments Sub-committee: Switzerland).
Olsen P, Weston M, Tzaros C, Silcocks A (2005) The state of Australia's birds 2005: Woodlands and birds. Supplement to Wingspan 15(4), 32pp.
Seddon JA, Briggs SV, Doyle SJ (2003) Relationships between bird species and characteristics of woodland remnants in central New South Wales. Pacific Conservation Biology 9, 95-119.
Watson J, Freudenberger D, Paull D (2001) An assessment of the focal-species approach for conserving birds in variegated landscapes in southeastern Australia. Conservation Biology 15, 1364-1373.
Watson J, Watson A, Paull D, Freudenberger D (2003) Woodland fragmentation is causing the decline of species and functional groups of birds in southeastern Australia. Pacific Conservation Biology 8, 261-270.