นกกาเหว่าคายกากอาหาร Koel casting pellet

Today in SRF I was looking at an Asian Koel นกกาเหว่า on a tabebuia rosea. Suddenly the bird opened its mouth and something emerged. It was casting a pellet.

It looked to me as if the pellet was mostly fibres and seeds, neither of which would be digestible, so this may be an efficient way of extracting nutrition without filling up the gut with indigestible ballast.