They're 3 weeks old this week. I think it's probably time, but I'd like confirmation. I've got the temperature in the brooder (big rubbermade bin) now down to the low to mid 80's with a 25 watt bulb, and they seem fine with that. I figure I'll still keep a heat lamp on in the cage for a while to make sure they are warm enough. Ambient room temp will be in the mid 70's, as its a warm summer, but I still only turn on the air when absolutely necessary, as I prefer the open windows and fresh air.