Dunlins and red knots tend to congregate in large flocks. Most of the time the birds in a flock are all the same species. However, flocks can sometimes be mixed. Dunlins are slightly smaller than red knots( 8.5 inches versus 10.5 inches) in length and about five inches smaller in wingspan( 17 inches versus 23 inches). In a mixed flock, they are difficult to tell apart, especially when flying. Short-billed dowitchers can also be mixed in. They are even larger at 11 inches long with 19-inch wingspans.
Below is a photo showing a mixed flock. A closer look at the photo reveals a flock of dunlins with several short-billed dowitchers, one or more red knots, and a few semipalmated plovers. Dunlins are distinguished by a black stripe down the tail. Dowitchers have a white stripe between their shoulder blades, and the red knot has a black and white checkered rump. On the ground, the size differences would be more apparent, and the longer bill of the dowitchers and the face patterns of the plover would be more prominent. This photo also points out another way the identity of an LBB can be determined— using the wing patterns that are visible only when the bird flies. Most shorebirds have four overlapping rows of feathers growing from the bones that correspond to the upper arm, the forearm, the thumb, and the hands of human beings. The rows correspond to the feathers in the primaries, secondaries, tertials, and the covering feathers called coverts. Similar rows of covering feathers are found on the underside of the wing as well as on the neck, back, and rump.
Beyond size, breeding / nonbreeding plumage, and wing patterns there are some LBB’ s that just look a lot alike. The three species of small plovers that are most common on Kiawah( the piping plover, semipalmated plover, and Wilson’ s plover) are all about the same size and have wing patterns that are very similar. The differences are in their coloration( including leg color), their face pattern and, to some extent, in their stance and foraging behavior. The piping plover is a very light tan as if it were faded. It has yellow legs and a short beak. They tend to feed on the over-washed sections of the beach.
Piping plovers.
The semipalmated plover has darker coloration and bolder facial markings with black masks around the eyes. Otherwise it is similar to the piping plover. Both give the impression of a plump little bird. Wilson’ s plovers are slightly larger, with a leaner body, longer legs, and different facial markings. They also have a darker, more prominent, and heavier beak. They tend to carry themselves differently than the other two birds. When nesting they will also try to distract you from the nest area by flying a short distance, landing, waiting for you to approach, then flying again. They will even fake a broken or damaged wing to entice the intruder closer, and when you come too close will once again fly away— all the while giving a distress call.
Many of the shorebirds have a prominent white stripe down the middle of the wing. The white stripe is the result of a row of dark feathers on the top of the wing covering longer white feathers in a lower row, which in turn overlie the still longer dark primary and secondary feathers used for flying. Differences in the colors of these overlapping rows of feathers on different species of shorebird determine the wing, back, and tail patterns. As we have seen, these can be important for identification.
Semipalmated plover. Wilson’ s plover.
10 Naturally Kiawah