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Fitting names for two common shorebirds

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Fitting names for two common shorebirds
Fargo North Dakota 101 5th Street North 58102

When it comes to putting common names to specific birds, some seem to fit quite descriptively while others make a person want to scratch their head and say, "Where did that idea come from?" For instance, there really isn't that much yellow (if you can see it at all) on a yellow-bellied sapsucker. But in the first category there are a pair of shorebirds that are so aptly dubbed that one might say, "Well duh." I'm referring to the greater yellowlegs (Tringa melanoleuca) and lesser yellowlegs (Tringa flavipes). Both birds strut around on rather long, bright yellow legs that are often the first thing an observer notices.

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Lesser yellowlegs are medium-sized birds (about 10 inches) with a slim, graceful appearance. Their dark straight bills are about as long as their heads. Backs of the species are brownish-gray with white and black mottling. Its breast and belly are mostly white with a variety of dark barring along the sides. Its head is heavily streaked with black and set off by a white ring around its eye. In flight a prominent white rump is easily visible.

After wintering along coastal areas from California and Virginia south to southern South America, lesser yellowlegs begin to arrive locally about mid-April. Eventually the birds end up on breeding territory in open boreal forests from Alaska to Quebec, usually on open ground near ponds. "Fall" birds (post-breeders) begin to arrive as early as late June. These are undoubtedly adult females since they depart the nest shortly after hatch, leaving the male to tend to its growing brood.

Greater yellowlegs are very similar visually to the lesser, only larger (about 13 inches), thus the name. But there are a number of behavioral differences. Greaters breed in the same geographical zone but in spruce bogs and muskeg. This makes it one of the least studied of all the shorebirds. I guess even field biologists can appreciate some level of comfort by shying away from slogging through inaccessible, mosquito-ridden bogs. Wintering areas are much the same but the greater will be found farther north. Both feed on invertebrates and small crustaceans but greaters are known to feed on small fish, at times exclusively.

Separating the greater from the lesser in the field is fairly easy once one is acquainted with the birds. At first one might think relative size would be easy to ascertain. Not so in the field, unless the two species happen to be standing near each other. So let's turn to finer points.

Voice is a good determiner. Lessers usually call with a two-noted "tu-tu." Greaters utter a rather loud "kyew" repeated three or four times. Bill size is another clue. Lesser: as long as its head; greater: about 1.5 times head length, often with a slight upturn. Groupings can also set the two apart. Lessers are known to be more gregarious, flocking and feeding in groups that are easily approached, while greaters tend to be found in smaller groups or even alone and spook fairly quickly.

Lesser and greater yellowlegs share a number of traits too. One is a tendency to bob its head up and down when an intruder approaches. Why this behavior takes place is the subject of debate among experts, but it is commonly observed. Both pick food at or near the surface of water or ground, not probing as some shorebirds do. Also, most shorebirds scurry around nervously while both yellowlegs species forage in a more methodical way.

Many migrant birds visit us for only brief periods in the spring and fall. With the yellowlegs species, we are fortunate to live in an area where from early spring until mid-October we have a reasonable chance at seeing one or both. Merely check out any wet farm field, slough, lake, or river shore and watch for bright yellow legs. After that, it takes a little practice to decide whether you are seeing a greater or lesser yellowlegs.

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