Opening mouth??

[macadam8157]

My chicks will perch or sit down for a nap and I've noticed them opening and closing there mouth alot. all of them seem to do this was just wondering what this is caused from??
Yawning? Are they hot? Grinding food?? I dont know????

 

[Pinky]

I think it's just yawning. I never worried about mine doing it. I really don't know why they do it. Maybe it's a cute chick thing