This is the first winter for my new aviary addition. The Chickens and Pigeons love it. It's safe, dry and warm. They love to take dirt baths and they lounge around laying in the warm sun like tourists on a beach. They're free to go outside, but prefer inside.
Whenever the aviary is over 50 degrees a thermostat turns on a fan to draw surplus heat inside to the insulated coop to warm it so the coop will remain warm all night long (free). The pigeon nests near the top are the warmest...the sand floor (about 85F degrees, 30C ) acts a bit like a heat sync during the day so at night the aviary is always about 10-15 degrees warmer than ambient, the inside coop remains well above freezing. It's all free heat. Even on cloudy days it's about 15-20 degrees above ambient. On those minus 40 degree nights a tiny elec heater (40w hair curler) keeps the coop above freezing. The elec bill for all winter is less than $5.
For more information click on Coop Design (temporarily disabled)