My cockatiel is rather sensitive to the cold thanks to his bald neck. Even though he's inside and we do keep the thermostat set at 72, he used to get too cold when it was below freezing outside. I tried heat lamps, but they kept him awake at night. You have to be careful with space heaters around birds because many space heaters have teflon, which has been known to kill birds. So, I invested in a special bird-safe heat panel that can either be hung on the side of the cage or mounted on the wall behind the cage. It keeps the temperature in his cage a comfortable 75-78, which seems ideal for him. When he's out of the cage, he usually hangs out on me, so gets my body heat.
