So today when I get home from work, I go out to check on my chicks (4 weeks old) as I do every afternoon after work and before work in the mornings. I quickly notice one of the RIRs has a piece of yellow twine hanging out of her mouth. I recognize the twine because I used it originally to put together the pen to keep them in. I abandoned the twine for wire in order to attach the panels together. At the time, I thought the twine I left on the panels was harmless. Big mistake - she had swallowed it. As I slowly begin to pull it out, I realize it is well past her mouth and more than likely down in her "innards". She allowed me to pull it out very slowly and by the time I got it all out, I had pulled around a foot of twine out of her. I watched her for a while and was relieved to find her eating and drinking just like the others. Hopefully, it didn't cause any damage. Lesson to be learned - never leave anything in the coop or pen that you wouldn't want your chicks to swallow, cause they definitely will.