The Indonesian islands of Java and Bali are both mountainous, rising to maximum altitudes of 3,676 m at Mt Semeru in eastern Java and 3,142 m at Mt Agung on Bali. There are numerous active and extinct volcanoes on the islands, and the fertile volcanic soils support some of the most intensive agriculture in the world-and c.60% of Indonesia's total population (FAO 1982a, RePPProT 1990).

The western half of Java, except for the northern coastal strip, has very high rainfall through most of the year and the natural vegetation is tropical rain forest. Bali and the eastern half of Java are affected by the Australian rain-shadow, and many areas have more seasonal rainfall, and the natural vegetation is deciduous monsoon forest. However, the south-facing sides of the mountains receive relatively high rainfall from the onshore winds, so there are isolated pockets of rain forest in the highlands of central and eastern Java and Bali, and locally in the lowlands along the south coast of Java (Whitmore 1984, A. J. Whitten in litt. 1993).

Most of the restricted-range bird species of this EBA are associated with rain forest, principally montane forest, but some occur in the lowlands and in drier forest types. They occur in the provinces of Jawa Barat (West Java), Jawa Tengah (Central Java), Jawa Timur (East Java) and Bali, and probably Yogyakarta. As montane forest above 1,000 m is the most important habitat of this EBA, and much of the forest below this altitude has been cleared, the 1,000 m contour has been used to delineate the EBA, but important lowland localities for the restricted-range bird species are also shown individually on the map. This EBA is adjacent to the Javan coastal zone (EBA 161), but the birds of that EBA are restricted to coastal (mainly non-forest) habitats, and there is little actual overlap between the two.

The restricted-range species of this EBA include two monotypic endemic genera, Psaltria, which is endemic to Java, and Leucopsar, which is endemic to Bali. There are close affinities with the Sumatra and Peninsular Malaysia (EBA 158), with which 12 restricted-range species are shared. An additional six species are endemic to Java and Bali, and several more are near-endemic (see Andrew 1992), but these are non-forest birds, or forest birds which have adapted to man-modified habitats, and occur in too wide a range of habitats to be treated as restricted-range.

Most of the restricted-range species are now virtually confined to montane forest, although there are historical records of several of them from the lowlands, which suggests that before extensive lowland deforestation took place they may also have occurred (at least locally) in lowland forest. Stachyris grammiceps and Macronous flavicollis are mainly found in the lowlands below 1,000 m, S. grammiceps mainly in remnant forest patches but M. flavicollis also in a variety of non-forest habitats. Leucopsar rothschildi is confined to a small area of lowland monsoon forest in western Bali.

All of the restricted-range species apart from L. rothschildi have been recorded in West Java, and several are known only from this part of the island, which may be a natural pattern related to the very high rainfall and relatively extensive areas of rain forest found there. However, West Java has been more intensively studied than the rest of the island, and some species may yet prove to be more widespread than is currently known. Recent fieldwork has, for example, extended the known ranges of Megalaima corvina and Psaltria exilis into Central Java (Robson 1994).

The form of Javan Frogmouth Batrachostomus javensis which is endemic to Java (and a restricted-range taxon confined to this EBA) was treated as a full species by Sibley and Monroe (1990, 1993), but is here considered as part of a more widespread species which includes Blyth's Frogmouth B. (javensis) affinis (following Andrew 1992).

Closed-canopy forest now covers less than 10% of the land area of Java and Bali (Collins et al. 1991). Most of this forest is montane, although several important areas of lowland forest are included in protected areas. Loss of forest cover has now virtually ceased, but degradation of the remaining habitats continues to be a threat, and the hunting and trapping of birds is widespread (MacKinnon and Phillipps 1993, D. A. Holmes in litt. 1993). West Java is the most extensively forested part of the EBA, and in Central and East Java and on Bali the natural forest is mostly confined to the upper slopes of the isolated volcanoes and other mountains.

Six of the EBA's restricted-range bird species are threatened, several because they are particularly restricted in range and therefore vulnerable to habitat loss; of the others, Spizaetus bartelsi is listed because it occurs at very low densities and prefers forest on the lower mountain slopes, Stachyris grammiceps because it is mainly confined to lowland forest, and Leucopsar rothschildi because it has a tiny range and population, and continues to be illegally trapped for the cage-bird trade (van Balen and Gepak 1994). More widespread threatened birds which occur on Java include: Green Peafowl Pavo muticus (classified as Vulnerable), which has declined throughout its large Asian range and whose relict populations on Java are now all scattered and threatened (van Balen and Holmes 1993); Java Sparrow Padda oryzivora (Vulnerable), formerly abundant throughout Java, Bali and the Kangean islands but now much reduced in numbers, apparently due entirely to massive capture for the cage-bird trade; and Straw-headed Bulbul Pycnonotus zeylanicus (Vulnerable), which has also declined rapidly as a result of excessive trapping.

Most of the remaining forest on Java and Bali is in the mountains, and much of it is already included in gazetted protected areas. Gunung Gede Pangrango National Park and Gunung Halimun Nature Reserve in West Java are notable, because they probably support populations of all of the restricted-range species-except for Leucopsar rothschildi, whose entire range is included within the Bali Barat National Park. Important areas of lowland rain forest are protected in Ujung Kulon, Alas Purwo, Baluran and Meru-Betiri National Parks (Ujung Kulon supports one of only two known populations of the critically endangered Javan rhinoceros Rhinoceros sondaicus).

Given the extensive forest loss and fragmentation which has taken place on Java and Bali, the following 21 forest areas are recommended as new reserves (FAO 1982a, Sujatnika and Jepson 1995): Jatiluhur/Sanggabuana, Ciogong, Cikencreng, Cipatujah, Gunung Limbung, Gunung Kencana, Gunung Masigit, Gunung Masigit-Kareumbi and Cimapang in West Java; Gunung Muryo, Pegunungan Pembarisan, Gunung Slamat and Gunung Perahu in Central Java; Teluk Lenggasana (Lebakharjo), Gunung Beser, Gunung Ringgit, Gunung Jagatamu, Gunung Liman Wilis, Gunung Raung, Gunung Kawi/Kelud and Maelang in East Java; extensions are recommended to Bali Barat National Park and Gunung Batukahu Nature Reserve.

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Java and Bali forest. Downloaded from https://datazone.birdlife.org/eba/factsheet/160 on 22/11/2024.