Identifying a bird can be a challenge, even for experienced birders. And if you're new to using field guides, it can be daunting to figure out where to even begin searching in the hundreds of pages of species.
There's a great technique for making positive identifications. It's all about knowing what to look for and in what order. Keep this checklist handy and follow it in order, and you'll be able to name that mystery bird!
The first and easiest place to start is size. Look at the bird and compare it to the size of species you're familiar with. Is the bird smaller than a sparrow, about the size of a pigeon, bigger than a goose?
If you're still unsure about the bird's size, look for an object near the bird you can use for comparison. For instance, if the bird is near something like a rock, a sign or a flower, you can go measure that object and get a rough idea of the size of the bird.
2. Overall shape
Look at the silhouette of the bird and compare this to species you know. Is it shaped like a robin, a heron, a duck, an owl? The overall shape of the bird can go a long way in narrowing down which section to look through in your field guide.
Next, look at the details of bird's shape. Zoom in on the shape of bill, wings, body, tail and legs. Again, it can be easier to notice and remember details if you compare these aspects of the bird you're looking at to the bird species you already know.
Is the tail long or short compared to the body? Are the legs long or short, slender or sturdy? Is the bill bulbous like a cardinal, thin like a hummingbird, hooked like a hawk or flat like a duck?
3. General behavior
Where the bird is located in a habitat and what it's doing can reveal information to help narrow down the species possibilities. Some of the questions about general behavior to ask include:
- Is the bird in a flock or solitary?
- Is it staying close to brushy cover or is it out in the open?
- If it is in a tree, is it staying high in the canopy or lower in the branches?
- If it is eating, can you tell if it is eating seeds, insects, nectar, plants or something else? Is it feeding on the ground or in water?
Notice everything you can about what the bird is doing because these subtle details will help distinguish the general category of bird and perhaps between species that look very similar but act differently.
4. Habitat and range
Next, you can rapidly rule out possible species by noting the habitat type and considering the range of the species.
What kind of place is this bird in? Is it a grassy plain, a marsh, a conifer forest or an oak woodland? A desert-adapted roadrunner is unlikely to be hanging out on a beach, just as a great blue heron is unlikely to be found on a mountain top.
The habitat type is equally helpful with subtle differences between species, too. Let's say there are two sparrows that both look like they could be your bird, but one is found in an arid habitat and the other is found only in forested habitats. You'll know which is your bird based on where you saw it.
Now let's say both of the two candidate sparrow species are found in conifer forest. You can narrow it down based on the range of the species. Is the conifer forest in the upper Midwest or along the West Coast? You can exclude candidate species that are very rarely or never found in the area where you're birding.
5. Color and field marks
Color comes last because many bird species have differently colored plumage based on sex, age, season and other factors. The very same male bird might look completely different in April when he has his colorful breeding plumage versus November when he's wearing his winter plumage.
Did you know bald eagles don't get their signature black body and white head until they're around seven years old? It can be easy to mistake a juvenile bald eagle in its mottled brown plumage for a somewhat similarly colored golden eagle — yet size, wing shape and habitat helps distinguish them.
Some bird species can look incredibly similar to one another. There's a reason why birders use the term LBJ, which stands for little brown job, to describe so many little brown sparrow species! Only the most subtle differences in markings — such as a pale gray versus a white marking near the eye — might distinguish two species from one another. That's why noticing other identifying characteristics first is critical, and noting color details will assist in finalizing a positive ID on a bird.
With the five checklist items above, you'll know where to begin to look in a field guide and how to pick out your species among similar species. However, if you need additional clues, you can include:
- Listening to its song or other vocalizations
- Watching its flight pattern — how it flaps its wings and maneuvers in flight
- Watching its flight silhouette — its overall shape in flight
These extra clues can feel difficult to learn at first but become much easier with experience — and can be your best tool for distant birds.
Want to practice using this list? Here's a quick quiz. Visit the Cornell Lab of Ornithology's page on the Bewick's wren and Marsh wren. Don't they look incredibly similar? Now use your checklist and the information on the pages to distinguish the two species. Note the difference between bill and tail length (overall shape), their different feeding preferences (general behavior), their different habitat preferences, where their ranges do and don't overlap, and the thickness of the white "eyebrows" (field marks). Play the sound files and notice how different their songs are, as well.