I have a 150 watt ceramic heater bulb running in my chicken tractor as I write this. The tractor is 8 feet long by 30 inches wide by 30 inches tall, and houses two hens: a buff orpington and a Rhode Island Red, both one and a half years old.
It is pretty cold by mid-south standards -- upper or mid 30's outside right now. The tractor is insulated except some on the top, where I made the mistake of not covering the insulation with plywood. They pecked a big hole in the insulation, which I have not had opportunity to repair yet.
Anyway, I just went out to check the ceramic heater and it's putting out enough heat to keep the tractor somewhat warm. Not toasty warm, but acceptable. The birds are sleeping about 3 feet away from it, on their roost, and seem OK.
Actually, I got worried about the use of that heater earlier tonight when I read on a website that these ceramic heaters are used mostly for reptiles and other cold blooded animals. They emit infrared light, which warms an animal from the inside out. The article I read said that is good for cold blooded creatures, but warm blooded animals (like man or chicken) do better with a heat that heats from the outside in (such as an incandescent brooder lamp).
Problem is, incandescent lamps are a greater fire hazard, plus birds can burn themselves on the incandescent lamps, but not the infrared ones. In small quarters such as these two hens live in, the issue of burning themselves on a hot bulb is something to be concerned about.
Plus occasionally a stray rain drop can get into the tractor, and that happened a few days ago. The incandescent brooder bulb I was using literally blew up when that happened.
So, unless somebody has an idea for a better way to heat my chicken's tractor, I guess I'll be sticking with the ceramic bulb heaters.
I found at amazon.com that you can buy them in different wattages: 60, 100, 150 and 250, however it is not an item that
amazon stocks. They farm out the business to one of several dealers, and no dealer had all of the available wattages.
I'm thinking about ordering a 250 watt one, in case it gets extremely cold or my two hens moult.