Ottawa West
Series of two (2) Photos.
The bizarre call of this member of the heron family is a distinctive "OONG-KA-CHOONK" or "OONK-A-LOONK" that some say sounds like a congested pump. The call has earned the A. Bittern the nicknames: "Thunder-pumper"; and "Stake-driver".
It is painful to watch. I hope it is not as painful to perform!
In the upper image, the call is about to be emitted; and one can see a bulge in the upper neck. In the lower image; the lower neck can be seen as inflated; the precursor to the call process.