Greater and lesser yellowlegs {Photos by Don Reimer)
Greater and lesser yellowlegs {Photos by Don Reimer)
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Determining the relative size of birds can be a tricky element in identifying them. Much of the time, size can be pinned to broad general categories. We might describe a small bird as the size of a sparrow or perhaps a robin. Larger birds can be relegated to being crow-sized and beyond. But size alone can be hard to judge from a distance. And the common names ascribed to certain species are slightly confusing, to say the least.

Let’s review four species of shorebirds with size-related names. These are the greater and lesser yellowlegs and short-billed and long-billed dowitchers. We can start with a comparison of the two species of yellowlegs.

As their name implies, yellowlegs have long, bright-yellow legs that are usually quite noticeable. Both species have a slender body profile and a thin, fairly long, straight bill. They feed actively, pursuing prey in shallow water and bobbing their heads when alarmed. Since these gray-and-white species closely resemble each other, how do we distinguish between them?

Greater yellowlegs measure about 14 inches in height, showing a slightly upturned bill that appears quite longer than the head. This is a subtle, but important feature. The foraging behavior of greater yellowlegs can provide additional clues, as they dash about and chase crazily through water in pursuit of small fish. Voice is another clue to their identification. This species has a loud, strident “dew, dew, dew” call that is repeated three to four times.

At a length of about 10.5 inches, lesser yellowlegs are a scaled-down version of their larger cousins. By contrast, their shorter bill length roughly equals the length of their head. This smaller species appears daintier and is more sedate in its feeding style as it picks and jabs at the water surface. If you are fortunate enough to see both species standing side-by-side, the size differences become readily apparent.

Folks consulting a birding field guide might be puzzled by the so-called “short-billed” dowitcher’s designation. Dowitchers are stocky, brownish-bodied birds, with lengthy bills and a white rump patch in flight. Their humped body posture and characteristic manner of feeding, using a nibbling sewing-machine-type motion, is somewhat diagnostic of the species. You might consider dowitchers as being nature’s “down-stitchers.”

In truth, the bill of the short-billed dowitcher isn’t really short at all. And bills of females are slightly longer than the males, reducing their inter-sexual competition for food. In some instances, female bills even overlap with long-billed dowitchers (particularly those L-B individuals on the shorter end of the bill spectrum). This all makes relative bill lengths a challenging way to distinguish the two dowitchers, but long-bills actually do have longer legs. And with studied, close-up views, feather color and intricate patterns in the wing feathers help a little.

What are the likely odds on local sightings of these similar migrant species? Short-bills are far more common along the Maine coast in fall, where they appear in tidal mudflats and flooded saltmarshes, such as Weskeag. Short-bills also tend to migrate in early- to mid-September. Only limited numbers of long-billed dowitchers are found here in late fall, but most of them follow a southern migration route from Arctic tundra breeding grounds through the interior U.S. These two species are best distinguished by their uniquely different flight calls. And if you occasionally struggle with mystery shorebird identities, please don’t feel alone. You have lots of company out there.