Choo Teik Ju was observing a male Common Iora (Aegithina tiphia) moving around the branches of a tree when it suddenly caught a caterpillar. With the caterpillar firmly clamped in its bill, the bird flew to another tree to eat it.
Still gripping the caterpillar in its bill, it gently swiped it against the branch a few times (left; below, top left). It then left it on the branch, looked at it for a short while as if to admire its handiwork (below, top right). Finally, it picked it up and swallowed it (below, bottom left and right).
There are reports that some birds can tolerate swallowing caterpillar, hairs and all. And that the hairs form a layer over the stomach lining to be subsequently regurgitated as a pellet. Other birds remove the stomach content before swallowing the caterpillar.
Is this Common Iora swiping the caterpillar to remove the hairs or the stomach content?