There are terms we use about which we don’t give much thought. On the face of it, their origin seems obvious enough, it’s just that we have no personal experience to give the expressions much tangible significance; they’re part of the common vernacular.
‘Eagle eyes’ is one of them. I was on a boat tour in George Inlet near Ketchikan. To demonstrate the power of bald eagle vision, the guide tossed a herring into the water. We were surrounded by nothing but trees onshore, part of the massive Tongass National Forest that covers most of southeast Alaska (Panhandle, as it’s commonly called). We waited. And waited. The guide thought it might be hunting elsewhere. Then, out of the forest it came, an eagle from easily a mile away. It circled for a bit, then came swooping down and plucked the fish out of the water. It was an incredible demonstration. Now I’ve seen eagle eyes with my own.