CR
Grey-rumped Myna Acridotheres tertius



Justification

Justification of Red List Category
Although this starling was previously fairly common, the species has become severely depleted in numbers through exploitation for the cage bird trade. Its population is estimated to number fewer than 250 mature individuals, largely restricted to locations where there is enforcement against trapping, and even so this population is still considered to be declining. As such, this species qualifies as Critically Endangered, and urgent conservation action is required to halt its unsustainable exploitation for trade.

Population justification
The population has been estimated at 200 individuals, with 190 estimated to be present within Bali Barat National Park in 2014 (Eaton et al. 2015). A very small number are present in the south of Bali, estimated to be 10 or fewer (Eaton et al. 2015). Assuming that the species is present on Nusa Lembongan there may a small number of additional birds but releases appear to be ongoing (Collar et al. 2012) and as it is not clear that there is an established breeding population, these are not included in the population estimate.

Trend justification
The population is inferred to be declining from the increasing rarity of this species in the cage-bird trade and dramatically increasing price, however records from the wild within its now very restricted range indicate that the rate of decline is not as great as that noted in A. melanopterus. The species remains highly desirable (captive-bred individuals costing over US$ 120 [Shepherd et al. 2015, S. Chng in litt. 2016]) and while there is little enforcement over the origin of birds offered for sale any birds that do remain in the wild are at risk of being captured and sold. Captive-breeding of the species is assumed now to be producing virtually all the birds being sold, but birds without closed rings were still being observed in the markets in 2014 (Shepherd et al. 2015). The current operation of the market does not appear to provide any disincentive to the capture of wild birds (Shepherd et al. 2016). But the restricted nature of the locations, and enforcement efforts ongoing to prevent capture of Bali Starling Leucopsar rothschildi at which this species is found and the slightly lower desirability than the white mantled A. melanopterus appears to limit the extremes to which trappers are prepared to go to to obtain this species.

Distribution and population

The species is endemic to the island of Bali, Indonesia, also (probably this species) occurring on adjacent Nusa Penida, and (perhaps only as a vagrant or escapee) on Lombok. Its range has changed little over recent decades, but it has undergone a rapid decline over recent decades. Most of the population is found within Bali Barat National Park, with a handful persisting at a single site in the south of Bali (Eaton et al. 2015). Individuals were released onto Nusa Penida in 1986, but it is uncertain that they were this species or perhaps A. tricolor or A. melanopterus. A very small number have been observed on the adjacent Nusa Lembongan recently, but there have been no reports from Nusa Penida itself since around 2011 (Eaton et al. 2015).

Ecology

Small flocks forage on the ground in a variety of habitats, mostly now in primary and secondary monsoon forest, forest edge and open woodland chiefly in the extreme lowlands. Formerly it was found in agricultural and livestock-grazed areas. Some flocks were thought to make significant local movements, following the flowering and fruiting of trees, but it is unclear if such movements still take place. 

Threats

Capture for trade is the primary threat, and the main cause of its decline. Many are now being captive-bred for the bird trade but it is unclear if there has been any attempt to maintain the distinction between this species and A. tricolor, which may appear very similar as immatures, and there is suspicion that there may be deliberate breeding with A. melanopterus to increase the value of the offspring, as A. melanopterus is more highly valued (Shepherd et al. 2015, S. Chng in litt. 2016). The release of such birds poses a serious risk of genetic introgression occurring in the wild population, though this may already be occurring. The high price the species commands in the market continues to provide a significant problem for the re-establishment of a population outside a well-enforced protected area.

Conservation actions

Conservation and Research Actions Underway
The species has been nominally protected under Indonesian law since 1979. It occurs in Bali Barat National Park, Bali, where the Bali Starling Project has helped with the prevention of poaching since 1983, but unlike Bali Starling is not listed on CITES. 

Conservation and Research Actions Proposed
Promote widespread, strict and effective enforcement of capture and trade regulations (including CITES listing [Shepherd et al. 2015]), focusing activities on protected areas and bird markets. Implement awareness raising activities to discourage people from purchasing protected wildlife (Shepherd et al. 2015). Develop the programme of captive breeding (Collar and Butchart 2013) and increase security measures at breeding centres to prevent further incidences of theft (Shepherd et al. 2015). Birds bred for potential release into the wild must be screened to ensure that genetic introgression does not occur. Conduct screening of birds in the locations where birds of uncertain origin have been released previously. Control use of agricultural pesticides (if these are found to be a significant constraint), especially in key areas for the species. 

Identification

23 cm. Medium-sized, stocky, piebald starling. Entirely clean white apart from a dark slate-grey mantle, grey rump, black wings and tail. Adults have a short white crest, naked yellowish or pinkish skin around eye and yellow bill and legs. Voice Loud, harsh whistles.


Acknowledgements

Text account compilers
Benstead, P., Calvert, R., Derhé, M., Gilroy, J., Khwaja, N., Symes, A., Wright, L, Ashpole, J, Martin, R

Contributors
Chng, S., Jihad, Mahood, S., van Balen, B., Miller, A., Iqbal, M., Brickle, N., Eaton, J., Winnasis, S.


Recommended citation
BirdLife International (2017) Species factsheet: Acridotheres tertius. Downloaded from http://www.birdlife.org on 16/10/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 16/10/2017.