stop laying without freeranging?

I am wondering if it is coincidence or real that the last several times I have had to leave the birds (ducks and chickens and geese) in the pen all day and not been home to let them freerange that egg production stopped. I figured it's related to being 100 degrees every day also, but they definitely lay some when they are out roaming around, but haven't been when penned up.

 

I doubt they ate them. I would see evidence of that behavior at other times, I would think. I am speculating maybe it's related to a combination of heat and social stress, being couped up with a lot of newer birds. I am trying to plan ahead for our family vacation in a week. I think I will try moving some of them to my "grower pen" to reduce the number of birds in the big pen and also try to find some more shade to increase the amount of shade for them. I worry though about putting up too much tarps, etc because of blocking what little wind we have also. I would think the sirflow is also important on these 100 degree days.
I let them freerange yesterday and collected 8 eggs after zero the day before in the pen. The trend definitely continues.