Have you ever seen a cormorant’s belch before?

This double-crested cormorant was sunning itself on a rock in Golden Gate Park. It was still a couple of hours before sunset and the light was fairly harsh, so I was playing with a backlit look and with the bokeh the sunlight made reflecting off ripples in the lake. All of of a sudden the cormorant reared back and opened its beak. I leaned on the shutter figuring I could get it “eating” a bokeh ball. It wasn’t until I reviewed the images that I realized it had been belching or something.

The internet tells me that scientists aren’t sure whether birds burp or not. Whatever this was, it wasn’t a normal exhalation. The cormorant is perfectly capable of breathing without opening its beak this wide. It wasn’t a particularly cold day, so a typical breath wouldn’t show up like this. If anyone knows what’s going on here, please let me know! (Irresponsible speculation is also welcome.)