Note From Field : Crested Serpent Eagle (Hunting & Territorial display)

After years of observing Crested Serpent Eagle I have in many occasion manage to observed the entire process of hunting. I was able to observed some good hunting and territorial display in Merapoh Taman Negara, Perak, Kuala Selangor and majority of the time in Penang. Most of the time this was observed in lowland and only on limited occasion hunting was observed in mountain area. My few successful observation was in Genting Highland and Cameroon Highland. Both provide me very good process observation. Observation was only limited to Malaysia with 2 occasion of hunting in Sabah and few more on territorial display. It will be great to see if consistency in East Coast of Peninsula Malaysia which I have limited experience on.

So what was observed in territorial?

Majority of the time observation on CSE calling in flight are on territorial display. Each time pair will fly together and calling. Where territorial meet with other group more pair can be observed flying nearby and all individual can be observed calling. In once occasion in Merapoh Taman Negara, total of 3 pair was observed and all three pair was calling. Circling within their territory but never enter and no conflict arise. Observation in Sandakan in one of the project yield the same result. Meanwhile in nesting period, female may be calling on perch which is to calling out to the male. There is no evidence on this display type to be territorial. 

What about hunting behaviour?

Meanwhile on the hunting it was noted that CSE practices perching hunting method. At current time during my observation 100% of all observation in hunting process are perching hunting. There was no documentation on my observation where soaring hunting was practices. The bird mainly perch quietly motionless unless movement from head. The prey will be detected from flight and once detected the CSE will flew directly to the prey. Prey item are mainly reptile consist of lizard such as garden fence lizard and snake which consist of both venomous and non-venomous snake such as Sumantra Spitting Cobra, Monocled Cobra, Bronzeback.

In one occasion an observation was made on a mangrove, a crab was observed to be a prey item.(see photo attach)

Approaching the prey are main done in two type. Where non venomous snake and lizard are hunted, the CSE approach directly to the prey and griping the snake or lizard directly during landing.

However, when approaching venomous snake the strategy have been switch differently. The prey are detect on perch. CSR will flew to the side of the prey or very near the prey but never snatch it directly. Once landed on the ground the CSE will strategised occasionally opening its wing to attract the snake attention. This will continue till the opportunity to attack the snake head available. The bird will directly attack the snake head killing it. If the bird is feeding the snake will be brought to the nearby perch for feeding. However if the bird is nesting in many occasion venomous snake are brought back with head almost severed or been severed. 

Although with such great predator strategy, in Naroaji book, it was noted that death case of CSE due to snake bite have been documented. On my observation however I have yet to have such encounter. Although some prey was observed to be a harder choice and more effort will be required. 

It will be great to know from other observer in the country on this observation and share the knowledge available which will be a great assistant to habitat management program.