The "chunnel" is now 50 feet long and offers a safe run along the back of the garden. This early snow formed a nice crust and offered some shelter from October cold. Later, I covered the first 20 feet of the chunnel with plastic. The chickens love to nap in the covered chunnel during the day and venture out to the uncovered portion for some fresh air and sunshine. 
We do not heat the coop. The chickens will develop fuller feathers as they acclimate to the colder temperatures. We did wrap the attached run to block the winter winds. I attached the tarp with small bungee cords that allow me to lower the tarp on sunny days and allow fresh air into the run. It also helps to dry out the sand if it gets wet from any blown in snow.