I apologize in advance for this. I know you were just getting comfortable with those pesky IDs—particularly with telling those big honkin’ Common Ravens and crafty little American Crows apart. You know about the bill size. You memorized the vocal difference. You were all set with the tail shape. But now I’m going to go ahead and throw a wrench in things. Please don’t kill the messenger. It’s my duty as an informative bird guy to tell you that it’s not quite as simple as “crow” or “raven.” There are actually three main crow species in the United States, and they’re a real pain to tell apart. Across the mainland you may find American Crows, Fish Crows, and Northwestern Crows. (We’ll save the two species of ravens for another day because we’ve got already enough to worry about. Likewise, we won't discuss the Hawaiian Crow, which is extinct in the wild, or the Tamaulipas Crow, which used to be common only at a landfill in Brownsville, Texas, but is...