There is a 125 watt heat lamp hanging from the nest bar they can get underneath. It's fairly warm here at the moment, so by the time it turns cold again, they will be six weeks old and mostly feathered.
I'm not entirely new to Delawares, to answer the previous question. I did hatch some from a friend's pair quite a while back and when they were about 8 weeks old, I sold every one of them. They were aggressive, flighty and generally unpleasant. My friend ended up culling both her hen and rooster because they were both very aggressive later. They were McMurray hatchery stock. My breeder friend had to convince me to hatch some from her flock. I'm very happy I did. I have a pullet from that batch laying already and she is with the laying flock till these guys are old enough for her to go in with them. I had two more but lost one to an unexpected heart defect and culled the rooster. These are the true heritage Delaware, deep bodied and beautifully marked. I'm very proud to have them.
