Habitat segregation in two congeneric hawk-eagles (Spizaetus bartelsi and S. cirrhatus) in Java, Indonesia

Abstract

Habitat segregation in two congeric hawk-eagles (Spizaetus bartelsi abd S. cirrhatus) in Java, Indonesia Nijman, V. Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract: On the island of Java, Indonesia, two congeneric hawk-eagles occur, i.e. the endemic Javan hawk-eagle Spizaetus bartelsi and the wide-ranging changeable hawk-eagle S. cirrhatus. Comparisons with similar species-pairs in South-East Asia suggest that these species may be competitors both in habitat and diet. The limited area and less-diverse resources of islands should make competition between similar species more acute and should lead to marked niche segregation, with a larger niche breath for the endemic species. Spizaetus bartelsi was recorded significantly more frequently in forest habitats from sea level to 2500 m asl and S. cirrhatus more in open habitats up to 1600 m asl. Contrary to the prediction, the endemic hawk-eagle occurred in a smaller range of habitats (four out of seven) compared with S. cirrhatus that was found in all seven habitat types. Although significant, habitat segregation was not as well marked as in some similar co-occurring Spizaetus species. The relative overlap between the two species may in part result from human influences with the dense continuous rain forest being replaced by more open forest types.

Spizaetus hawk-eagles as predators of arboreal colobines

“…Although a wealth of primatological research has been conducted in Asia (see reviews in Campbell et al 2007) as indicated by Janson (1998) the most direct method to explore the impact of predation on primate populations is to conduct studies of the predators themselves that would reveal the prey profiles for each predator. Spizaetus hawkeagles are notoriously difficult to observe in the rainforest, and may be rare (Nijman 2004b;van Balen et al 2000). Thiollay (1985) estimated that on average he observed only one raptor day -1 while walking slowly inside the rainforest.…”

Pelepasliaran Elang Jawa di Kawasan Cagar Alam Gunung Picis dan Cagar Alam Gunung Sigogor, Jawa Timur

“…Kawasan penyangga kedua kawasan konservasi tersebut adalah hutan lindung, hutan produksi dan ladang masyarakat yang menyediakan habitat tambahan untuk elang jawa. Thiolay & Meyburg (1988) menyatakan bahwa elang jawa bergantung pada hutan primer, namun Nijman (2004) menyatakan bahwa daerah jelajah elang jawa bisa mencakup daerah-daerah terbuka di sekitarnya. Hal ini sesuai dengan elang jawa di kawasan CA Gunung Picis dan CA Gunung Sigogor yang juga memanfaatkan kawasankawasan di sekitarnya sebagai area berburu dan berinteraksi dengan lingkungannya.…”

Pengelolaan sumberdaya hutan di era desentralisasi: pelajaran yang dipetik dari hutan penelitian Malinau, Kalimantan Timur, Indonesia

“…2000), di mana ada hubungan yang jelas antara pemanenan kayu dengan perburuan (Bennett dan Gumal, 2001). Pengaruh dari perburuan juga dilaporkan dari Kalimantan (Nijman 2004(Nijman , 2005Marshall dkk. segera terbit) dan diambil dari pengamatan pertama di kawasan hutan dengan tekanan perburuan mulai dari tingkat rendah hingga tinggi (Meijaard, pengamatan pribadi).…”