I recently built a chicken coop and purchased 9 buff orphingtons and a rooster from a local farmer. They've been great at laying eggs, but for the last two weeks I've noticed one chicken has not left her box. I assume this is because she is planning to hatch some eggs, which is fine. However, how can a chicken live for two to three weeks without ever leaving the nest? I thought virtually any animal would die if it didn't at least have some water periodically. I've never seen a chicken so still. Do I need to intervene in any way? I don't want to lose a chicken due to my lack of farming skills.