I have 5 Newhampshire Reds, and in the last week we have gone from averaging 4 eggs, to only 1 egg per day!! The only thing that is different in their routine is I changed their bedding straw to pine shavings. And I added a heat lamp to their coop for when it gets cold. I've searched and searched and searched my yard to no avail. There are NO other nests in my yard. I've also not heard any egg songs lately. Is this normal?! They are only 7 months old! Please help ease my mind!