in our first part of the series. reporter: way up in alaska, an airplane can feel like a time machine because the arctic national wildlife refuge, commonly known as anwr is the type of pure wilderness that america paved over a long time ago. there it is. we are in the heart of the arctic refuge. reporter: welcome to one of the last truly wild places on earth. brims with life from musk oxen to bears, both grizzly and polar. birds that will my great to the backyards of all 50 states. but as captured over the years, the most common creature is the caribou, and not just a few, put hundreds of thousands. the kind of herd unseen since the plains buffalo were wiped away. when he is here with his family,