I was out today, 31st October 2022, at the outskirts of Ipoh City where there are many ex-mining pools (wetlands-like habitat) and limestone hills. I observed a Changeable Hawk-Eagle (Nisaetus cirrhatus) hunting for prey. It was a juvenile (see images 1 and 2), on its own, that attempted to catch Grey Herons (Ardea cinerea).
I first spotted it fly past me, and I followed it as it landed in a ‘concealed’ section of an Albizia saman (Rain Tree) which housed a heronry. This heronry on the Albizia saman tree has 25-30 adult birds with 10-12 active nests, in various stages.
When the Changeable Hawk-Eagle approached and landed in the tree, all the adult Grey Herons gave out loud, continual distress calls. The Changeable Hawk-Eagle was located 4-5 meters above the highest density of nesting. The adult Grey Herons had their crest raised, wings outspread and continued to make loud vocalisation.
Over the next 30 minutes the Changeable Hawk-Eagle made four attempts to catch a Grey Heron. Twice it swooped down to the nesting birds (see image 3) but the nesting adults put up a fierce defence. Two other times it went after a flying adult Grey Heron but they managed to evade it. All attempts were unsuccessful. After each attempt it returned to the Rain Tree to a concealed perch.
An audio recording of the vocal distress of the Grey Herons can be heard here: https://xeno-canto.org/758701
The Herons were in various stages of nesting. Most were incubating eggs but a few had young chicks and 2-3 had juveniles close to fledgling. It seemed to target the nesting birds but also went after adults in flight. I suspect inexperience on its part resulted in poor hunting.
The ruckus attracted a number of Large-billed Crows (Corvus macrorhynchos) who came to the tree and subsequently chased off the Changeable Hawk-Eagle.
Changeable Hawk-Eagles are known to take a variety of animal prey which include reptiles (snakes, frogs, lizards), birds (chickens, White-breasted Waterhens, Spotted Doves, Quail, Peafowl) and mammals (squirrels, rats, hares, monkeys). The Asian Raptor Research and Conservation Network (2018) suggests that it prefers birds, including bush quail, spurfowl and jungle fowl.
Wells (1999) states, “believed to hunt mainly from concealment within tree-crowns”. My observations this morning of this hunting episode support this form of perch-hunting.
References:
- Gombobaatar Sundev, Tour Yamazaki (2018). Field guide to Raptors of Asia: Sedentary Raptors of Oriental and East Asia, Volume 2. Asian Raptor Research and Conservation Network.
- Wells, D.R. (1999). The birds of the Thai-Malay Peninsula: Vol. 1 (Passerines). Christopher Helm, London.
- James Ferguson-Lees, David A. Christie (2001). Raptors of the World. Christopher Helm.
Dato’ Dr Amar-Singh HSS)
Ipoh, Perak, Malaysia
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