Yeo Eng Chai’s video of a Daurian Redstart (Phoenicurus auroreus) casting a pellet is the most complete video documentation we have of the phenomenon. It clearly shows the gaping of the bill when the bird started the process of regurgitating the pellet, followed by the appearance of the pellet itself between the mandibles and ending in the pellet being cast out – see video clip below. Video grabs show the various stages – from top down.
We have an earlier account of the Daurian Redstart casting a pellet but only an image of the bird with a pellet between its bills LINK.
An earlier video by Jeremiah Loei shows similar details of a Black-backed Kingfisher (Ceyx erithaca) casting a pellet.
Such documentation needs luck and lots of patience. If the bird has eaten something, you need to wait for many minutes until it has compacted the undigested parts of its meal into a pellet before regurgitating it. On the other hand, if feeding was not seen earlier, you need luck to catch the bird casting a pellet.
Yeo Eng Chai
23rd November 2019