Thursday, November 15, 2018
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Wallace's Hawk-eagle (Nisaetus nanus)

As we were cruising up the Kinabatangan, we spotted this conspicuous clump of branches stacked rather untidily in the fork of a tree. We were delighted to find this pair nesting at the clump. We stayed quite a long while to look for good vantage points but alas the nest was really high up. Needless to say after ten minutes my neck was creaking under the stress of peering up at 80 degrees. But this pair of hawk-eagles were quite calm and generous with their poses, even exchanging places at the nest, as if taking turns for a photoshoot. We were however, looking for distinguishing signs at their feet to ensure this is indeed the Wallace's or was it an imposter.

Three suspects of this mimicry 'crime' are the Oriental Honey Buzzard, the Jerdon's Baza or the Wallace's Hawk-eagle. The hawk-eagle is considered the model and the other two the mimics. In this interesting behavior called Batesian mimicry, a smaller, less numerous species like the Jerdon's Baza would mimic the Wallace's Hawk-eagle to protect itself from attacks from larger eagles and other Wallace's too. The rare resident race of Oriental Honey Buzzard also mimics the Wallace's Hawk-eagle, although it is similar in size - so I'm not sure why it does that. I guess they have issues?!

Anyway, the key to distinguishing the Wallace's from the other two mimic birds is in the feet or tarsus - the Wallace's is feathered all the way to the base of the toes, while the other two would-be's do not have feathers on their tarsus.

This was the tree with the nest

Some other close ups of the Wallace's Hawk-eagle

 

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