There are other answers on how to keep the habitat warm enough to keep the water from freezing besides electricity. If you build the shelter for them so that the southwest facing wall is made of clear material such as glass or lexan short wave radiation from the sun will pass through and transform into long wave radiation inside the shelter and not be able to pass back through the walls. This is known as the greenhouse effect like what happens inside your vehicle. You can capture this type of radiation into materials such as large stones or pieces of concrete inside the shelter. These will release their energy slowly throughout the night helping to keep the inside of the shelter very much warmer than the exterior. You can also install a rainwater collection system on a solar powered pump to keep thier water source fresh and topped off while you are not there to care for them by hand. Water also absorbs heat from the sun and can be used to maintain a warmer interior. You can also place an automated feed inside of the shelter. It's really all in the design. The short answer to your question is that yes, it is possible to keep these bird alive throughout the wintertime in your area, but you will have some expenses to go through to get the shelter to that point. If you do not want to invest into the birds financially all at once on a sophisticate shelter like this your other option is to place the birds out in the hunting area every year to replace the birds that did not survive due to predation and cold. I think that you are going to have much better success investing more money up front by building a sophisticated insulated shelter that uses natural solar heat and energy to provide a survivable habitat for the birds than if you just plan to replace them every year due to the fact that each time you replace the birds you will need to cage them for six weeks so they know to remain on the property. Having a solid shelter for them will cost you more money up front, but much less in the long run because your habitat will be self sufficient and self replenishing and you will have to drive out to the property much less frequently to check on them. It can be done, its just a matter of how much you have to invest up front and how much you want to get rid of the excessive tick population. I'm in the process of doing the exact same thing on our hunting property.
