My banty chicks are going on six weeks old (next Monday). They're all very well feathered out and we've started turning off their heat lamp and letting them outside during the day, but we turn the light back on when we lock them up at night. In the last couple days though the temperatures have dropped (from the 80's and 90's to about the mid to high 60's). We've been leaving the heat lamp on inside but still giving them access to the outdoors. I think they're more than ready to handle outside temps, but I don't want to shock them with a sudden temperature change. What's the best way to ease them into the fall weather?