I know Caitlin is from Maine and she has showgirls and has hers out.YOur's are young yet I know they are more hearty when they are fully feathered out.I would think maybe chekc the temp. in your coop and then gradually adjust them down in temp.It is hard on any animal to just take them from inside the heated house and then throw them outside without heat.They need time to adjust.I know my banties which are cochins I put out in the barn at 1wk.it was middle of may a couple of nites it was really cold so I had a heat lamp low to the ground attached to plastic tote turned on its side they stayed in that alot I put the food and h20 bowls out further so they had to venture out to get it.