Differential extinction of forest species following forest fragmentation raises the questions of which populations are most prone to disappeaq and why. Hence we studied an 86–hectare woodland in west Java, the Bogor Botanical Garden (BBG), that became isolated when suwounding woodland was destroyed 50 years ago. Out of 62 bird species breeding in the BBG during 1932–1952, 20 had disappeared by 1980–1985, four were close to extinction, and five more had declined noticeably. The two main variables that identifl extinction‐prone populations in the BBG are 1) small initial population size in the BBG and 2) rareness or absence in the surrounding counttyside. Although the BBG retained wooded habitat, it is evidently too small to retain self‐sustaining populations of many woodland bird species. Small populations at high risk of extinction for stochastic reasons are doomed to disappear permanently unless subsidized by re‐colonization from the surroundings Thus, a too‐small reserve cannot function as a distributional island but comes to mirror the species composition of its surroundings More such case studies documenting species losses from small habitat fragments are required to demonstrate to nonbiologists the need for reserves large enough to support self‐sustaining populations.

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.

No abstract

The Endangered Javan hawk eagle Spizaetus bartelsi is threatened in part by the illegal pet trade. In 1993 the species was declared Indonesia's National Rare/ Precious Animal, by former President Soeharto. Trade in the species and keeping it as a pet are illegal. We consolidated data about the species in trade, as observed at bird markets, with private owners, in zoological gardens (to date the species has not been bred in captivity and those in zoos are all wild-caught that were formerly in trade) and wildlife rescue centres, involving at least 68 birds. The average price for the species at bird markets was USD 40 (n 5 5). The number observed at bird markets appears to have increased over time. Furthermore, prior to its declaration as a National Rare/Precious Animal it was not considered in trade to be different from other large eagles. There are indications that individuals have been illegally exported to other parts of Asia. In the early 1990s no Javan hawk eagles were kept in zoos but it became in demand in the mid 1990s and now there are 11 in six zoos throughout Java. Law enforcement with respect to trade in eagles appears to be largely absent but nine Javan hawk eagles have been brought to a wildlife rescue centre on Java. Overall, the data suggest there was an increase in trade in Javan hawk eagles after it was declared the National Rare/Precious Animal. When a threatened species is put in the spotlight to highlight its conservation plight, this should be done with close cooperation between conservation NGOs and government organizations, with appropriate legislation and/or management plans to prevent overexploitation.