Striated fieldwren (Calamanthus fuliginosus) sensu stricto - endangered species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the Striated Fieldwren, Calamanthus fuliginosus (Vigors & Horsfield, 1827) sensu stricto as an ENDANGERED SPECIES in Part 1 of Schedule 1 of the Act, and as a consequence, to omit reference to Calamanthus fuliginosus (Vigors & Horsfield, 1827) sensu stricto from Part 1 of Schedule 2 (Vulnerable species) of the Act. Listing of Endangered species is provided for by Part 2 of the Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. The Striated Fieldwren, Calamanthus fuliginosus (Vigors & Horsfield, 1827)  sensu stricto is listed as a Vulnerable species in NSW. The Rufous Fieldwren  Calamanthus campestris, of arid western NSW, was recently separated as a full species from the Striated Fieldwren (Schodde and Mason 1999; Christidis and Boles 2008) making a reassessment of the conservation status of both species desirable. A determination to make a minor amendment to the Schedules has been made in relation to  Calamanthus campestris.

2. The Striated Fieldwren sensu stricto (family Acanthizidae) is a small (12 cm), scrubwren-like, olive-brown songbird, heavily streaked, with a pale eyebrow and a cocked tail. It is darker and more olive than the Rufous Fieldwren,  Calamanthus campestris and occupies coastal rather than arid habitats. It is smaller and more streaked than the Eastern Bristlebird,  Dasyornis brachypterus and has a shorter tail with a white tip. It is more streaked than scrubwrens and heathwrens, and lacks the heathwrens’ bright rufous rump. The Little Grassbird,  Megalurus gramineus has a longer, unmarked tail.

3. The Striated Fieldwren lives on the ground in low, dense, mostly native vegetation (especially heathland in NSW) and in sedgeland, samphire and tussock grassland, often bordering wetlands (e.g. swamps, lagoons and saltmarsh). Its range extends from South Australia across Victoria and into NSW, and also includes Tasmania. In NSW it is restricted to the south-east coast, formerly occupying habitat from the Victorian border to the Blue Mountains (Higgins and Peter 2002). There are no recent records for the northern Blue Mountains (Bilpin) or Botany Bay, where small and isolated populations were last recorded in the 1970s (Higgins and Peter 2002), nor any recent reports north of the main populations in Morton National Park and Ben Boyd National Park/Nadgee Nature Reserve (Higgins and Peter 2002). Its extent of occurrence has declined by about 50% over 20 years between 1977-81 and 1998-2002 (Blakers  et al. 1984; Barrett  et al. 2003). The estimated extent of occurrence based on recent records in the NSW Wildlife Atlas is 3400 km². Four geographic populations encompass approximately 10, 20, 80 and 300 km² (410 km² total). The actual area of occupancy based on 2 x 2 km grid cells, the spatial scale of assessment recommended by IUCN (2008), is likely to be smaller than this estimate because of the scattered distribution of records within the largest population.

4. The size of the population is unknown for NSW, but presumed to be moderately low, with the species recorded at “sparsely scattered sites” (Higgins and Peter 2002). An average population density of 0.6 bird/ha was recorded during the 1990s in its NSW strongholds of Nadgee Nature Reserve and Ben Boyd National Park (Higgins and Peter 2002). However, comparison of survey results from Nadgee in 1977-81 (recorded in more than 40% of surveys per grid; Blakers et al. 1984) to those from 1998-2002 (recorded in 10-20% of surveys per grid: Barrett  et al. 2003) suggest a decline has since occurred. Lower population densities have been recorded in other parts of its range ( e.g. Victoria and Tasmania, 0.06-0.34 birds/ha: Higgins and Peter 2002). Reporting rates at Nadgee have approximately halved, and the lowest reporting rates (less than 10% of surveys per grid) apply elsewhere in NSW and adjoining parts of Victoria (Barrett  et al. 2003). A mean density of between 0.1 and 0.3 birds per hectare ( c. 0.2 birds/ha) may now apply across most of its NSW range ( cf. Higgins and Peter 2002), giving an estimated population of  c. 8100 (plausible range 4000-12000) birds in NSW.

5. The species has declined in some parts of its mainland range (Higgins and Peter 2002). In the first national bird atlas during 1977-81 the species occurred in five one-degree grids in NSW, at the lowest reporting rate (less than 10% of surveys per grid) except for the Nadgee grid where its reporting rate was high (greater than 40%: Blakers et al. 1984). In the second bird atlas during 1998-2002 it occurred in two southern grids (including Nadgee), at the lowest reporting rates (less than 10% and 10-20%: Barrett  et al. 2003). There were too few records in the atlases to statistically compare reporting rates in NSW in the two time periods (Barrett  et al. 2007). Reporting rates for the species showed no significant change nationally over this period (Barrett  et al. 2003).

6. Some habitat of the Striated Fieldwren has been lost to urbanisation and agriculture. The main threat to remaining heathland habitat of this species in NSW (much of which is now in reserves) is inappropriate fire regimes. Other threats include predation by cats and foxes, and degradation of habitat by weed invasion. ‘Invasion of native plant communities by Chrysanthemoides monilifera’, '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)’ and ‘Predation by the European Red Fox  Vulpes vulpes (Linnaeus 1758)’ are listed as Key Threatening Processes in NSW under the  Threatened Species Conservation Act 1995.

7. Calamanthus fuliginosus (Vigors & Horsfield, 1827)  sensu stricto is not eligible to be listed as a Critically Endangered species.

8. The Striated Fieldwren Calamanthus fuliginosus (Vigors & Horsfield, 1827)  sensu stricto is eligible to be listed as an Endangered species as, in the opinion of the Scientific Committee, it is facing a very high risk of extinction in New South Wales in the near future as determined in accordance with the following criteria as prescribed by the  Threatened Species Conservation Regulation 2002:

Clause 15

The geographic distribution of the species is estimated or inferred to be:

(b) highly restricted,

and:

(d) a projected or continuing decline is observed, estimated or inferred in:

(i) an index of abundance appropriate to the taxon, and
(ii) geographic distribution, habitat quality or diversity, or genetic diversity.

Dr Richard Major
Chairperson
Scientific Committee

Proposed Gazettal date: 23/04/10
Exhibition period: 23/04/10 - 18/06/10

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)

Christidis L, Boles WE (2008) ‘Systematics and taxonomy of Australian birds.’ (CSIRO: 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).

Higgins PJ, Peter JM (Eds) (2002) ‘Handbook of Australian, New Zealand and Antarctic birds (Vol. 6).’ (Oxford University Press: Melbourne)

Schodde R, Mason IJ (1999) ‘The directory of Australian birds: Passerines.’ (CSIRO: Melbourne)