Northern flying squirrel and boreal owl at the entrance to the same old northern flicker nesting cavity.  The flying squirrel taken with a Nikon D3s digital camera  and boreal owl shot with a Nikon F3 on Fujichrome film were taken more than ten years apart. The images illustrate the importance of the northern flickers, a keystone species. The flickers nest building activity increases forest biodiversity.  Photographs were taken near my home in Slana, Alaska.