Ever heard of this?

[punk-a-doodle]

Owls, Kookaburras, and other birds produce pellets. These are vomited up undigestibles from their stomach. http://biologycorner.com/worksheets/owlpellet.html
That's a better known example of bird vomit.

And trust me, vultures can vomit up their stomach contents, and do so willingly when stressed. Catch up day for vultures is no fun.

 

[TheBrumstead]

Parrots will regurgitate for their young and to show affection. I had a Sun Conure who always did that on my shoulder... gee... thanks!

 

[Redcatcher]

I think all birds that feed their young, regurgitate food when they are hatchlings. As the chicks age, the regurgitate spends less and less time in the crop. By the time the chicks have fledged, the food is either passed to them directly or else regurgitated to some degree. Small hulled seed for example where the crop is used for storage more than to break the food down.

 

[Redcatcher]

I watched a rooster drink a crop full of water yesterday, then immediately mount a hen. It all came up on the hen and she was not too happy.

 

[Dunkopf]

Quote:
Been there done that.