Abigail perched on the edge

Abigail perched on the edge of the brooder. When we get the chicks out to play with them, the other three come out quite readily, but Abigail flaps around and runs away from us as if she doesn’t want to leave her box. So we leave her in there, and as soon as she realizes she’s alone, she starts in with that pitiful cheeping. Then, a few seconds later, we hear a flap of wings and she appears just like this, ready to join us after all.