Do the pullets display a different behavior when they are ready to lay? Do they stay in the nest box prior to laying the first egg or go in and out a lot? Mine are ignoring the nests at this point of 21 weeks. Do they have a certain vocalization before or as they are laying the first time? Are there any links to sites to hear chicken sounds like this? I am listening through a baby monitor but not sure what I am listening for! Is it very distinctive and different from the everyday noise? Mine have reddened up a few weeks ago. There is no interest in the oyster shell.