102 BirdingASIA 11 (2009): 102

NOTEBOOK Observation of the mobbing of a Javan Hawk Eagle Spizaetus bartelsi by an Ashy Dicrurus leucophaeus in Yogyakarta, IMAM TAUFIQURRAHMAN

On the morning of 27 October 2007, while Merapi National Park. In that time I recorded 1,003 conducting a raptor migration watch on the Turgo migrants including Oriental Honey-buzzard Pernis Hill (07°35’1”S 110°25’28”E), Mount Merapi ptilorhynchus, Chinese Sparrowhawk Accipiter National Park, Yogyakarta, Java, Indonesia, I saw soloensis and Japanese Sparrowhawk A. gularis, a display of aggressive behaviour by an Ashy along with the almost daily presence of three Drongo Dicrurus leucophaeus towards a Javan resident species Black Eagle Ictinaetus malayensis, Hawk Eagle Spizaetus bartelsi, a Javan endemic, Crested Serpent Eagle Spilornis cheela and Spotted classified as an Endangered species (BirdLife Kestrel Falco moluccensis. On only this one occasion International 2004). did I record any aggressive behaviour by a small I was on the north-west side of the hilltop at an towards a raptor. altitude of about 1,300 m. At 09h51 I saw two Javan Similar behaviour has been described before Hawk Eagles flying and then soaring together. At (Nijman & Sözer 1995) from other areas on Java 10h23 one Javan Hawk Eagle, which I took to be and seem to top the list of the most one of the pair seen earlier, flew to the west on the aggressive bird species. They are well known for southern side of the hill only 100 m from where their pugnacity and fearlessness in attacking and I was standing. As I was watching it, an Ashy chasing larger such as crows and hawks Drongo suddenly appeared and mobbed the raptor (Campbell & Lack 1985: 357). Besides Ashy (Plate 1), calling noisily as it did so. The drongo’s Drongo, Dicrurus marcocercus, Black aggression lasted for about two minutes but, despite Eagle, Crested Serpent Eagle and Woolly-necked being chased and attacked, the eagle did not Stork Ciconia episcopus have been recorded mobbing respond except to turn its head towards the attacker Javan Hawk Eagles (Nijman & Sözer 1995). and change its direction of flight. I did not hear any vocalisation from the eagle. The mobbing Acknowledgement ended when the eagle flew away to the east, I would like to thank Siti Cholifah K. and Mehd presumably leaving the drongo’s territory. Halaouate for preparing the manuscript in English, Between September and December 2007, I spent Mrs. Dewi M. Prawiradilaga from Indonesian 164 hours observing migrating raptors in Mount Institute of Science (LIPI) for her kindness in reviewing it, and all of my friends in KPB Bionic Plate 1. Ashy Drongo Dicrurus leucophaeus mobbing Javan UNY and Jogja’s Birdwatchers Community that Hawk Eagle Spizaetus bartelsi, Yogyakarta, Java. helping me during the research.

References BirdLife International (2004) Spizaetus bartelsi. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. Campbell, B. & Lack, E. (1985) A dictionary of birds. London: British Ornithologists’ Union. MacKinnon, J. (1991) Field guide to the birds of Java and Bali. Yogyakarta: UGM Press. Nijman, V. & Sözer, R. (1995) Aggressive behaviour displayed towards the Javan Hawk-eagle. Kukila 7: 152–154.

Imam Taufiqurrahman, Kelompok Pengamat Burung Bionic (Biology UNY Ornithology Club), Universitas Negeri Yogyakarta, Karangmalang Yogyakarta 55281

IMAM TAUFIQURRAHMAN Email: [email protected]