Leaving chickens outside in winter
I'm new to the forum, and to chickens, and had a quick question. I bought twelve RIR layers in the fall, about a year old, and then later acquired an Ameraucana rooster. Right now I have them in a shed with a front about a third open to the outside, with a smaller (4'x6') insulated coop in the back. They don't get as much light as I'd hoped though, and I was wondering: does anyone let their chickens outside during the winter? What are the pros/cons to this? I'm looking to improve my set up for next winter, as we'll have a few more chickens then. We're in nw ON, and it does get cold here, -40*C with wind chill isn't unusual for the coldest part of winter during the day.
Any suggestions would be appreciated! I'm already planning my chicken tractors for this summer.