I've got three chicks about 4 weeks old they've got pretty good feathering on their wings and some starting to come in around their body. I've just moved them to a pen outside. I'm terrified to put a heat lamp in because I've had one catch fire before. Will they be okay without? It doesn't get below 50 at night and the coop is pretty well insulated and they have a nice layer of wood shavings. They've been doing just fine in my house at room temperature for a few days which is between 65 and 70. Thanks!