I have 7 hens that have all been laying for about a year. I have three nest boxes for them that they have been using since March. For the past couple months A couple of the birds had been laying eggs in the yard until I would find their stash and then they would lay in the nests again Suddenly, they all started laying on the floor of the coop in a corner. This has been going on for about a week. The only thing that may explain this is that one of our adolescent birds was caught and killed by a hawk last week. Is there anything I can do to encourage them to use the nests again?