You might not be thinking of bird migration in July and August, but this is the peak of southbound shorebird migration, when any mudflat is likely to provide a resting place for a few species, and the best locations can host 20 or more species together. Shorebirds (sandpipers and plovers) provide some of the most exciting late-summer birding opportunities, but they are widely known for being among the most challenging birds to identify. Many similar species are often in mixed flocks.
As with any other large group of similar species, the shorebirds can be subdivided into smaller groups of related species based on shared characteristics. Once you have found a flock of shorebirds, one of the best first steps is to figure out which of the subgroups are represented. Pay special attention to overall size and proportions, habitat choice, and foraging motions. Don’t worry too much about details of plumage at this stage.
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Four distinct groups encompass the majority of all of the shorebirds you are likely to encounter:
Plovers are small- to medium-size with short, stout bills. These species forage visually and move across the flats in short bursts, running a few steps, dipping down to grab something in the mud, then standing still to watch for their next target. Plovers almost never wade in water and are often found on the drier parts of the flats or even in dry fields. Killdeer is the most widespread and familiar species.
Yellowlegs are medium to large, elegant, with relatively long bill and legs. These birds forage mostly by sight, walking steadily and reaching down to pick food deftly from the surface of the mud or in the water. They do not probe in mud and are usually found wading in water.
Dowitchers are medium-size, stocky with very long bills and relatively short legs. The dowitchers forage entirely by touch and taste, probing repeatedly to find prey buried in the mud. Their bills move like the needle on a sewing machine. They often wade in water (sometimes walking on wet mud) with their heads down for long periods.
Peeps are small- to medium-size with relatively short legs and short, slender bills. This group includes the most numerous species (Least, Semipalmated, and Western Sandpipers), and the birds can be found in flocks of hundreds. They forage mostly by touch and taste, walking with short, quick steps and keeping their head down as they pick food from the surface or probe rapidly into the mud.
Other variations occur, of course. But these four groups include all of the most common shorebirds in most locations, and they’re a helpful first step to simplify their identification.
A version of this article was published in the July/August 2019 issue of BirdWatching.