This Conservation Advice was approved by the Delegate of the Minister on 11 April 2014

Approved Conservation Advice for Turdus poliocephalus erythropleurus ( )

(s266B of the Environment Protection and Biodiversity Conservation Act 1999)

This Conservation Advice has been developed based on the best available information at the time this Conservation Advice was approved; this includes existing and draft plans, records or management prescriptions for this species.

Description

Turdus poliocephalus erythropleurus (Christmas Island thrush), family Turdidae, is also known as the Christmas Island ground-thrush. The Christmas Island thrush is 21 to 22 cm long; it has a wingspan of about 34 cm, and a mass of 44 to 68 g. It has brown to dark-grey upperparts, a white chin and throat, a grey-brown to grey breast, dull orange flanks, and a belly that is dull orange on the sides and white in the centre. It has a dark brown iris, a prominent ring of yellow to orange-yellow skin around each eye, a yellow to orange bill, and yellow to orange-yellow legs and feet. The male and female are almost identical, but vary slightly in the colour of the bill. Immature are very similar to the adults, but retain some aspects of juvenile plumage (Higgins et al., 2006).

The Christmas Island thrush is a conventionally accepted of the island thrush Turdus poliocephalus (Schodde & Mason, 1999). It is the only subspecies (and the only member of the Turdus and family Turdidae) that is resident on Christmas Island.

Conservation Status

Turdus poliocephalus erythropleurus (Christmas Island thrush) is listed as endangered under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) under the name Turdus poliocephalus erythropleurus (Island Thrush (Christmas Island)). It was found eligible for listing as “it has a restricted geographic distribution occurring only on Christmas Island, predominantly in the forested area, an extent of occurrence of approximately 135 km². The estimated population is 15 000. There has been an observed decline in the habitat and reproductive success for this species and an inferred decline in the population due to the spread of Crazy Ant supercolonies. The direct threat of Crazy Ants has not yet been eliminated and the long term effects of the change in habitat are yet unknown” (TSSC, 2005).

A series of surveys conducted in 2005 and 2006 indicate that the population of the Christmas Island thrush is currently secure (James & Retallick, 2007).

Distribution and Habitat

Turdus poliocephalus is widespread throughout south-east Asia and the south-west Pacific with many subspecies. The Christmas Island thrush subspecies is endemic to Christmas Island. The two other Australian subspecies (T. p. poliocephalus from and T. p. vinitinctus from ) are now extinct (Garnett et al., 2011).

There is a single population of the subspecies and no reliable estimate of population size. The population was estimated to contain 4000 breeding birds and be decreasing in 2000 (Garnett & Crowley, 2000). The most recent estimate of 20 000- 50 000 individuals, derived from the result of a systematic survey in August 2002 (Corbett et al., 2003), is considered to be unreliable due to sample sizes and the assumptions involved (DNP, 2008). Present distribution has probably been reduced due to human settlement, mining and introduced predators but the species remains common: it was detected at 83 per cent of the 932 waypoints visited during the 2011 Island-Wide Survey (DNP, 2014).

Turdus poliocephalus erythropleurus (Christmas Island thrush) Approved Conservation Advice Page 1 of 4 This Conservation Advice was approved by the Delegate of the Minister on 11 April 2014

In 2000, it was surmised that the area of occupancy was declining in response to the spread of the introduced Anoplolepis gracilipes. However, crazy ant spread has been managed through island-wide aerial baiting since September 2002, and the results of a series of surveys conducted in 2005 and 2006 show that the Christmas Island thrush is currently secure on Christmas Island (James & Retallick, 2007).

The Christmas Island thrush is found in most habitats on Christmas Island, including tall closed evergreen rainforest, open semi-deciduous rainforest, secondary regrowth, thickets of weeds and semi-deciduous vines, settled areas (where it forages on lawns and nests on buildings) and on the Christmas Island golf course. It is most common in tall closed evergreen rainforest and open semi-deciduous rainforest on the coastal and higher terraces and plateau of Christmas Island. It is least common in disturbed habitats (such as regrowth and post-mining wasteland) and in suboptimal endemic vegetation such as Pandanus thickets and patches of low vegetation in coastal areas (Stokes, 1988; DNP, 2008).

This species occurs within the Territory of Christmas Island Natural Resource Management Region. The distribution of this species is not known to overlap with any EPBC Act-listed threatened ecological community.

The Department of the Environment has prepared survey guidelines for Turdus poliocephalus erythropleurus. The survey guidelines are intended to provide guidance for stakeholders on the effort and methods considered appropriate when conducting a presence/absence survey for species listed as threatened under the EPBC Act. http://www.environment.gov.au/epbc/publications/pubs/survey-guidelines-birds.pdf

Threats

The main identified threats to the Christmas Island thrush are introduced . The birds forage on the ground, so are exposed to contact with terrestrial predators such as cats Felis catus, black rats Rattus rattus and yellow crazy ants (Stokes, 1988). Black rats are known to have caused the of the island thrush on other islands.

There is insufficient evidence to indicate that the yellow crazy ant has caused a decline in the Christmas Island thrush population, however the potential for impacts has been demonstrated by a study that showed nest success and the number of juveniles encountered are lower in areas with crazy ants than without (Davis et al., 2008). The habit of the thrush to perch in low vegetation and forage on the ground, where densities of the crazy ant are greatest, make it susceptible to harassment or attack (Davis, 2002). The ants could also compete with the birds for food (Davis, 2002). However, in the 2011 Island-Wide Survey, little evidence was found of a negative impact of high density crazy ant colonies on the Christmas Island thrush’s distribution (DNP, 2014).

The main potential threats to the Christmas Island thrush include introduced diseases (Garnett et al., 2011); the introduction of new species and diseases; and ecological changes arising from the impact of crazy ants which could include favouring the spread of introduced predators (Garnett & Crowley, 2000), and changing rainforest composition to make habitat less suitable (O’Dowd et al., 1999).

The level of impact of each threat and potential threat is unknown.

Research Priorities

Research priorities that would inform future regional and local priority actions include:

• Conduct research on threats, including cats, rats, introduced ants and avian disease.

Turdus poliocephalus erythropleurus (Christmas Island thrush) Approved Conservation Advice Page 2 of 4 This Conservation Advice was approved by the Delegate of the Minister on 11 April 2014

Priority Actions

The following priority recovery and threat abatement actions can be done to support the recovery of the Christmas Island thrush:

Habitat Disturbance and Modification, including Invasive species • Continue measures to control the spread and abundance of crazy ants. • Control introduced cats and rats. • Improve biosecurity to maintain effective quarantine against the introduction of further invasive species and avian diseases. This includes rapidly controlling pests that may enter and assessing the risk of threat. Conservation Information • Coordinate implementation, including manage and analyse data, review the progress of recovery and effectiveness of management actions, and adapting actions if necessary. • Communicate with and engage the community and stakeholders regarding conservation of the Christmas Island thrush.

This list does not necessarily encompass all actions that may be of benefit to the Christmas Island thrush, but highlights those that are considered to be of highest priority at the time of preparing the Approved Conservation Advice.

Existing Plans/Management Prescriptions that are Relevant to the Species

• Christmas Island National Park Management Plan (EA, 2002) • Draft Christmas Island Biodiversity Conservation Plan (DNP, 2014) • Monitoring through the biennial Island-Wide Survey • The Action Plan for Invasive Ants on Christmas Island (Slip, 2002) • Threat Abatement Plan (TAP) for Tramp Ants (including Crazy Ants) (DEH, 2006)

These plans/prescriptions were current at the time of publishing; please refer to the relevant agency’s website for any updated versions.

References

Corbett L, Crome F and Richards G (2003). Fauna survey of Mine Lease Applications and National Park reference areas, Christmas Island, August 2002. Appendix G. In: Phosphate Resources Limited. Christmas Island Phosphates Draft Environmental Impact Statement for the Proposed Christmas Island Phosphate Mines (9 Sites) (EPBC 2001/487). Christmas Island: Phosphate Resources Limited.

Davis N (2002). The Invasive Yellow Crazy Ant (Anoplolepis gracilipes) on Christmas Island, Indian Ocean: Impacts on the Frugivorous Bird Fauna. Hons. Thesis. Honours thesis, Monash University.

Davis NE, O’Dowd DJ, Green PT and Mac Nally R (2008). Effects of alien ant invasion on abundance, behaviour, and reproductive success of endemic island birds. Conservation Biology 22: 1165-1176.

Department of Environment and Heritage (DEH) (2006). Threat Abatement Plan to Reduce the Impacts of Tramp Ants on Biodiversity in Australia and its Territories. Canberra, ACT: Department of the Environment and Heritage. Available on the internet at: http://www.environment.gov.au/resource/reduction-impacts-tramp-ants-biodiversity- australia-and-its-territories

Turdus poliocephalus erythropleurus (Christmas Island thrush) Approved Conservation Advice Page 3 of 4 This Conservation Advice was approved by the Delegate of the Minister on 11 April 2014

Director of National Parks (DNP) (2008). Christmas Island Biodiversity Monitoring Program: December 2003 to April 2007. Report to the Department of Finance and Deregulation from the Director of National Parks.

Director of National Parks (DNP) (2014). Christmas Island Biodiversity Conservation Plan – Draft. Department of the Environment, Canberra.

Environment Australia (EA) (2002). Third Christmas Island National Park Management Plan. Department of the Environment and Heritage, Canberra.

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

Garnett ST and Crowley GM (2000). The Action Plan for Australian Birds 2000. Canberra, ACT: Environment Australia and Birds Australia. Available on the internet at: http://www.environment.gov.au/biodiversity/threatened/publications/action/birds2000/in dex.html.

Higgins PJ, Peter JM and Cowling SJ, eds. (2006). Boatbill to Starlings. In: Handbook of Australian, New Zealand and Antarctic Birds. 7. Melbourne: Oxford University Press.

James DJ and Retallick K (2007). Forest Birds of Christmas Island: A Baseline Survey of Abundance. Parks Australia North Christmas Island Biodiversity Monitoring Programme. Canberra, ACT: Department of Finance and Administration and the Department of the Environment and Water Resources.

O’Dowd DJ, Green PT and Lake PS (1999). Status, impact, and recommendations for research and management of exotic invasive ants in Christmas Island National Park. Environment Australia, Darwin.

Schodde R and Mason IJ (1999). The Directory of Australian Birds: . Melbourne, Victoria: CSIRO.

Slip D (2002). Invasive Ants on Christmas Island Action Plan, February 2000-February 2003. Parks Australia North, Christmas Island.

Stokes T (1988). A review of the birds of Christmas Island, Indian Ocean. Australian National Parks and Wildlife Service Occasional Paper.

Threatened Species Scientific Committee (TSSC) (2005). Listing on Island Thrush (Christmas Island) (Turdus poliocephalus erythropleurus). Available on the internet at: http://www.environment.gov.au/biodiversity/threatened/species/turdus-poliocephalus- eurythropleurus.html

Turdus poliocephalus erythropleurus (Christmas Island thrush) Approved Conservation Advice Page 4 of 4