Justification of Red List Category
This species occupies a small range, in which it is known from only a few locations, and there are on-going declines in the extent and quality of habitat owing primarily to logging and agricultural expansion. These threats, coupled with likely hunting pressure, suggest that the species is undergoing a rapid population decline. For all of these reasons the species is classified as Vulnerable.
Its population was initially estimated at 1,000-10,000 individuals, but it has subsequently been found at several more sites and may considerably exceed this upper limit. It is restricted to two or three forest blocks, that total an absolute maximum of 225,000 ha of suitable habitat, which, considering home range sizes of c.8-20 ha found in other tropical partridges, suggests that a total of 11,000-28,000 pairs might still be present, but hunting pressure and variable habitat quality could mean that numbers are much lower than this (B. van Balen in litt. 2012). On the basis of this information, its population is conservatively estimated to include 10,000-19,999 mature individuals.
Remaining forest continues to face logging pressure and the clearance of fragments is commonplace, whilst the species may also suffer some amount of hunting pressure; hence, it is suspected to be declining rapidly overall.
Arborophila orientalis is apparently restricted to the eastern part of East Java, Indonesia, from the Yang Highlands eastwards, and thus occupies a range which historically covered only c.7,000 km2 and which today covers less than 2,500 km2. Its population was initially estimated at 1,000-10,000 individuals, but it has subsequently been found at several more sites and may considerably exceed this upper limit. The remaining area of suitable habitat suggests that a total of 11,000-28,000 pairs might still be present, but hunting pressure and variable habitat quality could mean that numbers are much lower than this (B. van Balen in litt. 2012). Its population is conservatively estimated to include 10,000-19,999 mature individuals.
While data on this species are extremely scant, current information suggests that it is similar to its close congeners in that it frequents the interior of montane evergreen forest, from 500 m (but usually above 1,000 m) on mountains whose summits tend to be higher than 1,700 m. It is also probably relatively resilient to habitat degradation and hunting pressure, although this remains to be confirmed.
Most forest in the Yang Highlands has been cleared, while elsewhere in the range of this species degradation occurs along the edges of remaining blocks and clearance of fragments remains commonplace (owing to logging and agricultural encroachment), steadily reducing its habitat. Furthermore, partridges are frequently caught and eaten or traded by local people on Java (Nijman 2003). The combination of these factors is likely to be reducing its population quite rapidly.
Conservation Actions Underway
A game reserve (perhaps embracing 15 km2 of forest) has existed in the Yang Highlands since 1962, although this has proved an ineffective designation. It also occurs in Meru Betiri National Park and the Kawah Ijen Ungup-ungup Nature Reserve. There is a small captive population (c.20 birds) in Belgium.
c.28cm. Stocky, short-legged, forest-dwelling partridge. Generally grey, barred darker on lower back and tail, with blackish crown and nape, and conspicuous whitish forehead, cheeks and throat. Wings brownish with dark tips to inner wing feathers and rufous on flight feathers. Black bill and red legs. Reddish orbital skin. Voice Undocumented.
Text account compilers
Taylor, J., Bird, J., Benstead, P., Keane, A., Tobias, J.
van Balen, B., Nijman, V.
BirdLife International (2023) Species factsheet: Arborophila orientalis. Downloaded from http://www.birdlife.org on 08/02/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 08/02/2023.