A friend just dropped off 2 chicks. They are supposed to be 34 days old. They have feathers and are just starting to cluck. They spent so much time scratching in their cage, I put the cage outside so they could have some dirt and grass to scratch in. Do I have to bring them in tonight? Temp during the day is mid-70's, but it drops into the 40's at night. Could I just cover them with a blanket to help them stay warm at night? Thanks.