SummaryThe Javan Hawk-eagle Spizaetus bartelsi is endemic to the island of Java. Severe habitat fragmentation and small population size, aggravated by illegal hunting have put this rainforest species on the list of threatened bird species. Intensive searching since 1986 resulted in the discovery of a large number of localities additional to the historic ones. All known locality records of Javan Hawk-eagle have been scrutinized and are listed in the present paper. Confirmed post-1980 records are from 24 forest fragments of varying sizes: 10 (including 28 discrete localities) in west, seven (including 14 discrete localities) in central and seven (including 20 discrete localities) in east Java. The configuration of available habitat in forest clusters is evaluated. The co-existence with other threatened bird taxa, and the need for further field surveys and studies of the Javan Hawk-eagle are discussed. RingkasanElang Jawa Spizaetus bartelsi adalah sejenis burung pemangsa yang endemik di Pulau Jawa. Penghuni hutan lebat ini dimasukkan ke Daftar Burung yang Terancam Punah karena populasinya yang kecil dan habitatnya yang makin sedikit. Survai-survai intensif sejak tahun 1986 menghasilkan sejumlah lokasi baru sebagai tambahan dari lokasi penemuan yang sudah diketahui sejak dahulu. Semua lokasi Elang Jawa diperiksa dan didaftarkan oleh kami. Semua lokasi pasca-1980 yang dapat kami pastikan berasal dari 24 blok hutan yang bervariasi ukurannya: 10 areal (termasuk 28 lokasi) di Jawa Barat, 7 areal (termasuk 14 lokasi) di Jawa Tengah dan 7 areal (termasuk 20 lokasi) di Jawa Timur. Pengelompokan dan penyusunan kantung-kantung hutan habitat Elang Jawa akan kami evaluasi. Keberadaan jenis-jenis burung lain yang terancam punah, dan perlunya survei-survei lanjutan serta studi lapangan mengenai berbagai aspek biologi Elang Jawa akan kami diskusikan.

Indonesian birds are especially threatened both by habitat loss and trapping for the cage‐bird trade. This paper describes recent zoo‐supported work at Cikananga Wildlife Center, Java, for the conservation breeding of a number of threatened passerine birds. The founder populations of these birds were obtained from local private bird keepers. Zoos and similar‐minded conservation organizations have backed this work through both funding and technical support. Conservation breeding has been highly successful for the Black‐winged starling Sturnus melanopterus and Sumatran laughingthrush Garrulax bicolor. A more recently initiated programme for Javan green magpie Cissa thalassina has already resulted in breeding success and another programme has recently been initiated for the Rufous‐fronted laughingthrush Garrulax rufifrons. Reintroduction trials have already been initiated for Black‐winged starling and others are at the planning stages.

Summary:The Javan Hawk-eagle Spizaetus bartelsi is one of the rarest and least known birds of prey, regarded as globally endangered and confined to the last remnants of forests left on the densely populated island of Java, Indonesia. Its biology is little-known and only a few cases of breeding have been reported. Systematic observations in 1992 and 1994 of two breeding pairs in the rainforest of the GedePangrango National Park, West Java, are described in this paper. In total over 100 h of observation were made and covered different stages of the breeding cycle. Clutches consisted of one egg, incubated for 47 ± 1 days predominantly by the female, to whom the male brought prey. After the egg hatched the female joined the male in hunting. The male was rarely seen on the nest as copulation and prey transfer took place mainly on nearby trees. After fledging the eaglet stayed near the nest for at least two months. A prolonged post-fledging period followed, the juvenile remaining with its parents for more than one year.The Javan Hawk-eagle Spizaetus bartelsi is one of the least known raptors in the world (Meyburg et al. 1989). The species is confined to the last remnants of forest on the densely populated island of Java, Indonesia. Due to the ever-decreasing area of natural forest left on Java, and more recently due to an increase in trade of birds, the species is considered globally endangered (Collar et al. 1994).Since 1986 a number of surveys have been conducted on the distribution and population status of the Javan Hawk-eagle including some identifying management priorities (e.g. Mooney 1997) and now the species is known from more localities than ever. The current population is estimated at a maximum of c. 200 breeding pairs (SvB, VN & RS unpubl. data). The species occurs in the ever-wet rainforest, which is largely restricted to the western half of the island, to the south and southeastern slopes of the higher volcanoes more to the east, and in some deciduous forest, which is more common to the eastern part of the island. As in many tropical rainforest raptors, information on demography and breeding biology is almost completely lacking (Thiollay 1985(Thiollay , 1994Clark 1994). Burton (1989) commented: 'with no information concerning the nest, eggs or habits of the bird currently available, it is difficult to envisage how any sort of conservation strategy can be developed, and at least for the present, the bird's future must remain precarious'. Recently this biological information was essential to establish a framework for a recovery plan to protect the Javan Hawk-eagle from further decline .Until now few cases of breeding by Javan Hawkeagles were recorded (Bartels 1924;Bartels 1931;Sözer & Nijman 1995a;Røv et al. 1997). The nest and egg have been described (Bartels 1924;Hellebrekers & Hoogerwerf 1967;Meyburg et al. 1989;Røv et al. 1997) and some details on different stages of the breeding cycle have been reported Sözer & Nijman 1995a) This paper describes aspects of the breeding biology and breeding requirement...

The endemic Javan hawk-eagle Spizaetus bartelsi is considered threatened with extinction because of its small population size and fragmentation of its habitat on the densely populated island of Java, Indonesia. Like many other tropical forest raptors little is known about many of its population parameters. Research was carried out from 1980 to 2000 in order to assess the status of this species. Its presence was confirmed throughout the island in both wet and dry climatic zones. Home range sizes were calculated to range between 12-36 km2, and comparison with published estimates suggests that these may differ significantly between areas. Encounter rates are in the order of 0.1-0.9 birds per survey day, and were significantly higher in areas with a short dry season compared to areas with a long dry season. Based on field-observations, museum skins and captive birds, the adult: non adult ratio is 1: 1.3. An assessment of habitat quality for all large areas where Javan hawk-eagles have been recorded, and a conservative working density differentiated to habitat quality, lead us to estimate that there are 137-188 remaining pairs, which account for a total world population of just short of a thousand birds. We make a number of suggestions for further research aimed at obtaining more insight on dispersal, recruitment and age-related habitat preferences, and for improved conservation, including more strict law enforcement and gazettment of new reserves.