Apparently you can get water heaters for wild birds and other pets, too, they're in most hardware stores. A lot of them are perfect for the coop provided you have an electric outlet. Sometimes they're cheaper than poultry supplies. Remember to shield the cord with a metal spring or something if it doesn't have a guard.
http://www.forthebirdsnatureshop.ca/sto FQodChXdyw
http://www.snowcountrypets.com/products FQodI0xDMA


http://www.forthebirdsnatureshop.ca/sto FQodChXdyw
http://www.snowcountrypets.com/products FQodI0xDMA

