Crop question

[Tishrei]

I've always been curious about this and tried to find the answer on the internet but could not. It's not an issue but am just curious.

Since my bird, Ducky, is self plucked, I can see some things that I normally would not be able to see if he were fully feathered. I realize that his food goes into his crop and it gets big when there's food in it. I can always tell when's he's been eating as I can see his crop.

My question does not have to do with food but him puffing it out on purpose. What he does is, or it seems like, he'll take in some air and fill his crop with air and it's huge. It can be virtually empty and I'll watch him puff it out with air. I've watched him do it. My question is what's the purpose of a bird doing that? Does it aid in digestion?

Thanks,

[birdlady49]

You might be seeing an air sac inflating and not the crop. Air sacs are located all over a bird's body. Their respiratory systems allow them to fly long distances without running out of breath. At the same time some of the sacs are inhaling, others are exhaling. Here's a diagram of where the air sacs are located: Avian Respiratory Anatomy