most people ask if they need a heating lamp for chicks with out a mother. YES you do! 2 of my chicks died without having a heating lamp or heater. once I put up the heating lamp no one else died or should any signs of being sick.
The only exceptions for chicks having a heat lamp is if they're with their mother or if the temperature is already hot. (One poster on this site had to remove a heat lamp when their little chicks started panting.)