I have 3 hens that just started laying 2 days ago. They are free range chickens, last night when I went to shut up the coop I noticed one was missing. I looked every where bit could not find her, this morning I went to let the others out and she came running to me. Well tonight only 2 hens again and it's supposed to be 16 degrees. Can anyone tell me why she would do this....hopefully she'll show up in the morning.