I haven't had eggs chirp much unless they were cold (by accident I found this out). However, I have had an incubator chick hatch and dry off in the incubator, then I took it outside to pop under moma hen. She had two babies already but they were only about two days old. She heard the incubator chick cheeping with cold, and started calling to it with great concern. I shoved it under her and everyone was quiet. No problems with her accepting that baby. But then, she hadn't left the nest for good with her other hatchlings yet.