An update: Clucky was found today, alive, well and... not clucking.  After working through her chicken angst, she walked up to us from out of the forest and wanted to be picked up.  We did so, and gave her her favorite treat (safflower) and put her in the coop.  We are keeping all the birds in the coop a few days to let them better bond, and Scuttle, our Head Rooster, is doing his best to encourage all of the hens to adopt her as one of their own.  She is now sleeping in the midst of the other birds and is still not clucking!  We may have to change the name of this once-cranky bird!