Like many species of waterbirds, shorebirds often fly in mixed flocks. Call me crazy, but looking through a mixed flock of fast-moving birds trying to sort out all the species involved is one of my favorite things to do. It can be quite a challenging exercise and requires concentration, stable optics and the ability to judge size and shape quickly.
Personally, I’ve always had difficulty picking out Stilt Sandpipers in distant flocks of Yellowlegs. During the fall, flocks of Yellowlegs are frequently seen flying in and out marshy wetlands. In many areas these flocks may include a few Stilt Sandpipers and the challenge is to sort through each shifting flock of gray birds for the slightly different gray birds. Any help in accomplishing this is a very good thing, so I was very happy to run across this excellent photo of a Stilt Sandpiper with a Lesser Yellowlegs that really highlights the differences. The photo was taken by Joyce Stefancic at Merritt Island National Wildlife Refuge in Florida and Joyce kindly allowed me to share it here.
Not only does this photo clearly show the differences between the two species, it highlights the utility of good comparison photos for learning bird identification.
I perceive the Lesser Yellowlegs (rear) as having a more “balanced” appearance as the wings are a little more centered on the body. It also has a stockier body, a larger head, but a shorter, straight bill.
The Stilt Sandpiper (front) is much leaner, the wings are moved subtly forward on the body and a little bit of the legs project beyond the tail in addition to the feet. This creates an unbalanced impression as there is more body/legs and feet behind the wings than on the Lesser Yellowlegs. Because the bill of both species is very narrow, the longer bill of the Stilt Sandpiper does not influence the impression of the balance of the bird as much as it would if it were heavier and more noticeably. Though it is not very apparent here, the Stilt Sandpiper also has slightly narrower, more pointed wings and, in addition to the smaller head, the crown is flatter. This last trait is a pretty subtle and may or may not be apparent in the field. Hopefully I’ll have a chance this weekend to get out and give it a try!
Cameron Cox currently leads photographic birding tours all over the world. To learn more about these tours or to sign-up for one, please visit the Tropical Birding website.