An important question is raised here: how come there are many, many recordings of bird calls, but none of birds doing other things? They certainly must make sounds regurgitating (I have seen mother birds do this, and a revolting maternal spectacle it is), and engaging in other bodily activities. Where is the Folkways Recording of Bird Flatulence from Around the World? This is surely a lacuna (a red-breasted lacuna) in the sonic archives.

yours, Peter T.