My chickens are 21 weeks and have not laid any eggs yet. Today my EE named Rosemary has been very vocal and frantic. She loudly proclaims "BAWK, BAWK, BAWK, BAWK" as she paces in and out of the coop and run, jumps up on top the nesting boxes, back down, up on the roost, down, outside, inside etc. The other 3 are going about their normal daily behavior, eating, resting, dust bathing, but she just keeps pacing and squawking. If I hold her she'll calm down and rest a bit, but then goes back to her pacing etc. Is this normal behavior as they prepare to lay their first egg? When do I need to worry that she might be egg bound or something? I'd appreciate any advice.