Zosterops albogularis

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

Bibliography

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AVES	PASSERIFORMES	ZOSTEROPIDAE

Scientific Name:

Zosterops albogularis

Species Authority:

Gould, 1837

Common Name/s:

English	–	White-breasted Silvereye, White-chested White-eye
Spanish	–	Gafudo Gorgiblanco

Assessment Information [top]

Red List Category & Criteria:

Critically Endangered B1ab(v);C2a(i,ii);D ver 3.1

Year Published:

2012

Assessor/s:

BirdLife International

Reviewer/s:

Butchart, S. & Symes, A.

Contributor/s:

Christian, M., Dutson, G., Holdaway, R., Ward, R. & Watson, B.

Justification:
This species appears to have declined as a result of predation by introduced rats, exacerbated by habitat destruction and degradation through invasion of exotic weeds. Formal surveys have failed to find any in the last two decades. There have been a number of other reports during 1978-2005, however a three-week survey in 2010 failed to find the species and estimated a 90% chance that the species is functionally extinct. A tiny population may however remain and therefore it is treated as Critically Endangered.

History:

2011	–	Critically Endangered
2010	–	Critically Endangered
2009	–	Critically Endangered
2008	–	Critically Endangered
2004	–	Critically Endangered
2000	–	Critically Endangered
1996	–	Critically Endangered
1994	–	Critically Endangered

Geographic Range [top]

Range Description:	Zosterops albogularis is endemic to Norfolk Island (to Australia). It was reported as "very plentiful" by Hull (1909) and 12 specimens were taken in one week in 1926 by Correia. However, the population is thought to have fallen below 50 individuals by 1962 (Mees 1969), and by the 1970s it had become confined to weed-free indigenous forest in and around the Norfolk Island National Park. Although formal searches have failed to find any in the last three decades, there have been scattered sightings throughout this period (Schodde et al. 1983), including one in 1987, two in 1991, four in 1994 and one in 2000. Since then a number of unconfirmed reports have been logged from the Norfolk Island National Park, most recently in 2006 (B. Watson in litt. 2006, G. Dutson in litt. 2009, 2010). The remaining population, if any exists, is likely to be very small; a comprehensive three-week survey in November 2009 based on 353 point counts failed to find the species and concluded there was a 90% chance that it was functionally extinct (G. Dutson in litt. 2009, 2010).
Countries:	Native: Norfolk Island
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	The remaining population is assumed to be tiny (fewer than 50 individuals and mature individuals), with only scattered sightings since 1978
Population Trend:	Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	It appears to occur mostly in weed-free indigenous forest, feeding high in shrubs and trees. However, there are old records of it nesting in orchards (Hull 1909), in red guava Pisidium cattleianum trees, and feeding on olive fruits (Mees 1969).
Systems:	Terrestrial

Threats [top]

Major Threat(s):	The principal threat is probably predation by black rat Rattus rattus, which is thought to have been introduced in the mid-1940s. The effects of predation have been exacerbated by the clearance of much native forest and invasion of the remainder by exotic weeds. As a result, favoured habitat has been reduced to less than 1% of the area of the island. Competition from the self-introduced Silvereye Z. lateralis, which was first recorded on the island in 1904, may also have contributed to the decline, and recent drought years may have stressed the population further (R. Ward in litt. 2006). Predation by feral cats Felis catus may also be a threat. The species may be vulnerable to climate changes and appears to fare poorly during dry years.

Major Threat(s):

The principal threat is probably predation by black rat Rattus rattus, which is thought to have been introduced in the mid-1940s. The effects of predation have been exacerbated by the clearance of much native forest and invasion of the remainder by exotic weeds. As a result, favoured habitat has been reduced to less than 1% of the area of the island. Competition from the self-introduced Silvereye Z. lateralis, which was first recorded on the island in 1904, may also have contributed to the decline, and recent drought years may have stressed the population further (R. Ward in litt. 2006). Predation by feral cats Felis catus may also be a threat. The species may be vulnerable to climate changes and appears to fare poorly during dry years.

Conservation Actions [top]

Conservation Actions:	Conservation Actions Underway CITES Appendix I. Surveys were carried out for the species, without success, in 2009 (G. Dutson in litt. 2012). Rat baiting, cat trapping and control of other invasive plants and animals is occurring in Norfolk Island National Park. Responsible cat ownership is being encouraged through sponsorship of cat neutering clinics. The species is being considered in a multi-species management plan for Norfolk Island National Park. Possibilities of captive breeding and securing additional funding to finance recovery efforts are being pursued. A predator exclusion fence has been proposed for Norfolk Island National Park to create a predator free "island" within the park (B. Watson in litt. 2006), and the proposal is now supported by the WWF and the Norfolk Island government. The Australian government has recently rated Norfolk Island very high on its list of the Australian islands in which they are considering the eradication of invasive rodents, with a possible $20 million investment in the chosen islands over a number of years (M. Christian in litt. 2008). Conservation Actions Proposed Determine a method for finding the birds reliably and conduct thorough surveys to estimate the remaining population size. Survey both native and introduced vegetation, as some recent reports refer to the latter (R. Holdaway in litt. 2012). Establish cooperative rodent control programmes throughout Norfolk Island, with a view to rat eradication throughout the island (G. Dutson in litt. 2012). Enhance rat baiting and cat trapping on Norfolk Island and monitor their efficacy. If birds are located, perhaps consider whether establishing a captive-breeding population is feasible. Continue to restore native habitat across Norfolk Island. Introduce to Phillip Island following revegetation. Gain support and funding from external sources to facilitate conservation actions.

Conservation Actions:

Conservation Actions Underway
CITES Appendix I. Surveys were carried out for the species, without success, in 2009 (G. Dutson in litt. 2012). Rat baiting, cat trapping and control of other invasive plants and animals is occurring in Norfolk Island National Park. Responsible cat ownership is being encouraged through sponsorship of cat neutering clinics. The species is being considered in a multi-species management plan for Norfolk Island National Park. Possibilities of captive breeding and securing additional funding to finance recovery efforts are being pursued. A predator exclusion fence has been proposed for Norfolk Island National Park to create a predator free "island" within the park (B. Watson in litt. 2006), and the proposal is now supported by the WWF and the Norfolk Island government. The Australian government has recently rated Norfolk Island very high on its list of the Australian islands in which they are considering the eradication of invasive rodents, with a possible $20 million investment in the chosen islands over a number of years (M. Christian in litt. 2008).

Conservation Actions Proposed
Determine a method for finding the birds reliably and conduct thorough surveys to estimate the remaining population size. Survey both native and introduced vegetation, as some recent reports refer to the latter (R. Holdaway in litt. 2012). Establish cooperative rodent control programmes throughout Norfolk Island, with a view to rat eradication throughout the island (G. Dutson in litt. 2012). Enhance rat baiting and cat trapping on Norfolk Island and monitor their efficacy. If birds are located, perhaps consider whether establishing a captive-breeding population is feasible. Continue to restore native habitat across Norfolk Island. Introduce to Phillip Island following revegetation. Gain support and funding from external sources to facilitate conservation actions.

Bibliography [top]

	Garnett, S. T.; Crowley, G. M. 2000. The action plan for Australian birds 2000. Environment Australia, Canberra. 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. IUCN. 2012. IUCN Red List of Threatened Species (ver. 2012.1). Available at: http://www.iucnredlist.org. (Accessed: 19 June 2012). Mees, G. F. 1969. A systematic review of the Indo-Australian Zosteropidae (Part I). Zoologische Verhandelingen 102: 1-390. Schodde, R.; Fullagar, P.; Hermes, N. 1983. A review of Norfolk Island birds: past and present. Australian National Parks and Wildlife Service, Canberra.

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

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.

IUCN. 2012. IUCN Red List of Threatened Species (ver. 2012.1). Available at: http://www.iucnredlist.org. (Accessed: 19 June 2012).

Mees, G. F. 1969. A systematic review of the Indo-Australian Zosteropidae (Part I). Zoologische Verhandelingen 102: 1-390.

Schodde, R.; Fullagar, P.; Hermes, N. 1983. A review of Norfolk Island birds: past and present. Australian National Parks and Wildlife Service, Canberra.

Citation:	BirdLife International 2012. Zosterops albogularis. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 21 May 2013.
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