It's good that people are considering the possibilities that eating snow will cause dehydration or lower body temperature, however wild animals from large to small like deer, fox, coyotes, squirrels down to the tiniest of birds get hydrated by eating snow in the winter. I cannot see why a chicken can't do the same, in fact from my experience they can. Does it take more volume of snow? Yes, so just give them enough snow. I throw in a shovelful every day and they never eat it all. Of course it depends on how many chickens you have. A large flock will take more. I only have 5-6 chickens so a shovelful is more than enough. I have never lost a chicken in the winter and our winters here in Alberta, Canada can get down to -35 or colder, my coop is not heated although it's very well insulated. In terms of body temperature, eating snow has never affected them negatively, they strut about outside in their pen quite happily even on the coldest of days.