She might be "just missing" for a night. If you were there all day and evening and didn't hear a commotion, she may be roosting in a near-by tree, bush, or something. When it gets dark, those chickens can't see and if dusk creeps up on them, they'll go to the nearest sheltered site and roost. In the dead of winter just last year, we thought ALL chickens were accounted-for. Had a HUGE snow storm overnight. Huge. Next day, sunny, bright, I see Geraldine (a plucky Black Star) come out from under a tarp so close to the ground you'd have thought it was almost part of it. She started rooting in the snow, scratching and pecking as though nothing was ever amiss. Seemed impervious to the circumstances.
It's possible she's gone for good, but it's also quite possible she's just weathering her circumstances.
Don't fear. This is the way it goes when you raise chickens. They pull at your heart strings but in the larger perspective of life, they're here to enhance ours. And make you smile.
