Birds come in all sorts of eye-catching hues, which makes them easier to spot in busy backdrops. But color isn't always the best place to start when trying to identify a species. Bluebirds aren’t always blue, goldfinches aren’t always gold—if we just focus on color, we may have to learn the same species over and over. Here are some other hints birders can rely on to get to the bottom of the mystery.
With over 800 species of birds in North America alone, it's helpful to narrow the choices down from the get-go. Scientists use dozens of different families to group avians: It pays to learn which traits define each family. Noting that a bird is gray isn't as useful as recognizing that it’s a gray owl, or a gray gull, or a gray sparrow-like bird. Hone it down to the family level, or to a group of families, and you’ll be halfway home on the final ID. You'll even learn the subgroups in each family as you go along.
This is really an extension of the first clue: A bird’s shape lets you place it in the right group. Even among closely related birds, practically no two species share the same exact shape. Sandpipers, for example, all differ in leg height, bill shape, neck length, and other elements of shape. On some similar pairs of ducks, such as Greater and Lesser Scaup, or Common and Barrow’s Goldeneyes, the silhouette of the head and bill is really one of the best ID clues. Even when you’ve identified a bird by some other means, it’s a good idea to spend an extra minute studying its shape so you can recognize it in the future.
This gets only half a point, because it’s such a tricky thing to judge on a lone individual. If you can view a mystery bird in direct comparison to one that you recognize, it’s good to note whether the bird is a little smaller than a robin, larger than a coot, and so on.
Sometime we become so captivated by a bird’s good looks that we fail to notice what it’s actually doing. Is the bird hopping on the ground, climbing a tree trunk, wading in water, or flitting in the treetops? If it’s climbing a tree, is it hopping up like a woodpecker, creeping along the bark like a Brown Creeper, or scuttling upside down like a nuthatch? Is the bird all alone, or part of a flock? These behaviors can all point to its identity.
Creatures on wings are highly mobile, and can wander outside of their typical habitats, especially during migration. But most of the time, habitat is an excellent clue. You might see a Horned Lark on the ground in a plowed field and a Red-eyed Vireo in a forest treetop, but you’re very unlikely to see them trade places.
Birds are surprisingly predictable when it comes to timing—for many it's a matter of life or death. Local books or checklists can tell you about the seasonal occurrence of species in your area. For example, in much of the northern United States, the easiest way to tell two rusty-capped sparrows apart is to glance at the calendar: Chipping Sparrow if it's summer, American Tree Sparrow if it's winter.
6. Field marks
It’s also good to get into the habit of looking for certain kinds of markings. Does the bird have a white ring around the eye, or a pale stripe above it? Is the body marked with round spots, lengthwise stripes, or crosswise bars? Does the target have white outer tail feathers? These “trademarks of nature” often will pin down the species for you.
Most birders start with a visual ID, and don’t really tackle “birding by ear” until later. But if your mystery bird is making some distinct sound, it’s worthwhile to try to make a note of it.
. . . And then, finally, it’s good to muse on the bird’s colors! With practice, you’ll be able to recognize most birds by the kinds of clues listed above. Then you can relax and just enjoy the striking hues for their own sake.
An earlier version of this article contained illustrations by Charley Harper