Monday, July 30, 2012

Identification of the Yellowlegs Complex by Shape

The Yellowlegs Complex includes Greater and Lesser Yellowlegs, Solitary Sandpiper, and Willet.  The Willet is the least similar to the rest and should be able to be identified quickly and easily.  The Solitary is also readily identifiable in most situations.  The identification between the two yellowlegs species is the real challenge for most birders.  If these species are seen together the size difference between each makes the identification simple.  But when seen separately, it can be difficult to recognize size differences.  All four of these species are long-legged, medium to long-billed, elegantly shaped shorebirds and shouldn't be confused with other species.

All four species are compared in the graphic below:

GRYE-Greater Yellowlegs
LEYE-Lesser Yellowlegs
SOSA-Solitary Sandpiper
WILL-Willet
Click on the image to see larger
The yellowlegs have the most similar plumage so shape is a more important factor than it is when trying to differentiate the other two species.  Even with a distant look and just a little experience the difference in bill shape is obvious.

Greater Yellowlegs:  Bill about 1.5X the length of the head with a slight upturn near the end.  Fairly large headed in comparison with Lesser Yellowlegs

Lesser Yellowlegs:  Bill just a little longer than the length of the head.  Straight, thin, needle-like bill.

Solitary Sandpiper:  Relatively thick, medium lenght, slightly decurved bill.

Willet:  Bill about the same length as Greater Yellowlegs but much more substantial.  Thick, heavy, straight bill.

-Eric

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