This sound!!??? What’s going on?

So- I have a flock of four that are all the same age and one started making these crazy noises about a week ago. Two days ago she laid her first egg and I have heard her also singing the egg song which was more of a bock-bock- bgawk!!! This one is different. Otherwise she’s acting totally fine and sweet. Anybody have any experience with this? Here’s a video. Sometimes she goes on for a bit longer and louder if you can believe it.

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