Dred

I was given two box turtles and they're living in my back yard. The yard is enclosed. I'm told they may be Ornate Box Turtles. I was given them by someone who had several, and was advised that they can live in the outdoors and that they'll eat dog food.
I've read a bit about box turtles and have been feeding them dog food as well as some fruits and vegetables. I'm told they will hibernate in the winter. I live in Albuquerque, New Mexico and it has been dropping to the 40's at night now, but it's still 70 during the day. Any advice about feeding or hibernation would be appreciated!