I had my brooder light (heat source) go out one night. The bantam chick I had put in with my week old quail babies saved the day. They were all three huddled together in the drastically cool brooder. Thank goodness I had that bantam chick in there or I probably would have lost my two quail babies.
My duck Miss Wonky was my extra heat source for my baby quail in the winter when she was a duckling, they spent more time cuddling with her than near the lamp. She had bad legs and couldn't stand so she lived with the quail so she wouldn't get knocked around. They provided her companionship and she was a warm ball of fluff for them to snuggle with.