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Slender-billed White-eye Zosterops tenuirostris

Justification
This species is listed as Near Threatened because although it has a very small range and population on a single island (and has declined historically), its population is estimated to have been stable for several decades. It has not been significantly affected by introduced predators, including rats, and therefore there is not thought to be any plausible threat likely to lead to very rapid future declines. If such a plausible future threat were to be identified it would warrant classification as Vulnerable.

Taxonomic source(s)
Christidis, L.; Boles, W. E. 2008. Systematics and taxonomy of Australian birds. CSIRO Publishing, Collingwood, Australia.

Identification
13-14 cm. Medium-sized, warbler-like bird with long, slightly decurved bill. Sexes similar. Greyish-brown upperparts, including head and flanks, with olive cast. White eye-ring. Black lores. Suffused olive-yellow upperwing-coverts. Yellow-tinged undertail-coverts. Grey bill, paler lower mandible. Similar spp. Silvereye Z. lateralis is grey on back and chest, has shorter, straighter bill, is less yellow overall. White-chested White-eye Z. albogularis is larger with white underparts. Voice High-pitched. Wheezier and more sibilant than Z. lateralis. Hints Tends to forage on branches and bark more than Z. lateralis.

Distribution and population
Zosterops tenuirostris is found on Norfolk Island (to Australia), where it is thought to number c.4,500 mature individuals, mostly restricted to the Norfolk Island National Park. It underwent declines since the 1960s, particularly outside the park, which continued in the period 1987-1997, however numbers since appear to have stabilised.

Population justification
A survey in 2010 estimated a population of c.4,000 birds in the National Park on the basis of 74 records in point counts at a density of c.900/km2; the total population has therefore been estimated at 4,500 mature individuals (Garnett et al. 2011).

Trend justification
The species has been declining since the 1960s, particularly outside the Norfolk Island National Park, a decline which has continued in the period from 1987 to 1997 (Garnett and Crowley 2000). Numbers are since thought to have stabilised, as a 2010 survey found detected similar numbers along transects to previous surveys (Garnett et al. 2011).

Ecology
It lives in rainforest and tall secondary growth. It uses its long, down-curved bill to probe fissures in bark for insects, although it also takes fruit, including those of exotic species. It is also observed feeding on nectar from flowers of the endemic Pittosporum bracteolatum (M. Christian in litt. 2007). It forages in parties and appears to have a different ecological niche to that of the self-introduced Silvereye Z. lateralis.

Threats
The species has gradually disappeared from all parts of the island that have been extensively cleared for timber, cultivation, pasture and continued development (M. Christian in litt. 2007). This species is also presently threatened by the replacement of cleared native forest with invasive weeds (M. Christian in litt. 2007). Its decline was probably exacerbated by the arrival of black rat Rattus rattus. Cats are opportunistic predators of adult birds (R. Ward in litt. 2007).

Conservation Actions Underway
The Norfolk Island National Park was declared in 1986, encompassing most of the main remaining stands of native trees on the island. Rat baiting and cat trapping is carried out within its boundaries. In 2006, it was noted that control measures for rats were budget-constrained and limited in their effectiveness (S. Garnett in litt. 2006). Responsible cat ownership is being encouraged, through sponsorship of a cat neutering clinic. The Norfolk Island Region Threatened Species Recovery Plan (Director of National Parks 2010) recommends a set of recovery measures required to reduce or remove threats to native species on the island. Rabbits have been removed from Phillip Island. Conservation Actions Proposed
Monitor trends in the population through analysis of birdwatchers' records. Consider introducing the species to Phillip Island. Install a predator-proof fence around the national park, Hundred Acre Reserve and other important areas of habitat, and remove introduced predators from within these areas (M. Christian in litt. 2007). Eliminate mammalian predators from the entire island, or at least significant sections, and prevent reintroduction (Director of National Parks 2010). Carry out research into the impacts of introduced predators (M. Christian in litt. 2007).


References
Director of National Parks. 2010. Norfolk Island Region Threatened Species Recovery Plan. Department of the Environment, Water, Heritage and the Arts, Canberra.

Garnett, S. T.; Crowley, G. M. 2000. The action plan for Australian birds 2000. Environment Australia, Canberra.

Garnett, S.T., Szabo, J.K. and Dutson, G. 2011. The Action Plan for Australian Birds 2010. CSIRO Publishing, Collingwood.

Further web sources of information
Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.

Australian Govt - Action Plan for Australian Birds 2000 - Recovery Outline

Click here for more information about the Alliance for Zero Extinction (AZE)

Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Ekstrom, J., Garnett, S., McClellan, R., Symes, A. & Taylor, J.

Contributors
Christian, M., Garnett, S., Holdaway, R. & Ward, R.

Recommended citation
BirdLife International (2014) Species factsheet: Zosterops tenuirostris. Downloaded from http://www.birdlife.org on 27/11/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 27/11/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Key facts
Current IUCN Red List category Near Threatened
Family Zosteropidae (White-eyes)
Species name author Gould, 1837
Population size 4500 mature individuals
Population trend Stable
Distribution size (breeding/resident) 8 km2
Country endemic? Yes
Links to further information
- Additional Information on this species