Two rivals broke American birdwatching's biggest record - and they're still racing.

This quest is referred to as a North American "Big Year," and the goal is to see as many as you can of the almost 1,000 species on the American Birding Association's list for the continental United States and Canada in a year. (It was fictionalized in the 2011 box office flop "The Big Year.") From 1998 to 2013, the record was 748 bird species.