Hmmm, my chickens must be as weird as myself. I'm in Northern Vermont, we've had good snow cover for about 3 weeks now, since early November this year (but next week should hit 50 degrees & rain Tuesday with 20 degrees Wednesday...) My chickens always go out free range, unless I lock them in, which I do when the temp or wind chill will be 10 belowF or so. I've got horses, so I've got sheds too, but the birds go everywhere. Of course, I am very careful to get cold-tolerant bird variants, it would be irresponsible to do otherwise.
I get a few new chicks each year, and they are always the last hens to leave the coop when it first snows. They look out the door, look at me, clearly give me a "WHAAAAAT?" look, then a few days later they are also outside. Compost scraps get dumped outside and who wants to miss the treats for too long just because of a little snow?!
So, I think chickens can easily learn to be snowbirds, but you must provide more feed, a draft-free coop (notice I didn't say heated), and expect fewer eggs. I just use a light on a timer starting mid-November, once most everyone has finished their molt cycle. It comes on early enough to provide 13 hours of daylight (barely able to read a newspaper brightness) I only provide supplemental heat when it drops to about 5 degrees Fahrenheit, and that's a single 70 to 100 watt incandescent bulb with a reflector way out of reach. If you heat the coop consistently, you put the birds at a disadvantage going outside since they can't put on sweaters...