Ptarmigan / poop

Ptarmigans have the funniest calls and for some reason just tickle me in general.

Then, later, I saw this big pile of poop and learned from one of the scientists here that it is ptarmigan poop. I just cannot mentally accept that a relatively little bird like this can produce poop this enormous. Not to put too fine a point on it, but this volume of poop seems almost equal to the volume of the bird's body. How is this possible?!?