Flocks of migrating shorebirds drop into the state during spring and fall migration, creating identification challenges – and frustrations – for many birders. A wild double take of the least and western sandpipers can reveal key features like leg coloration; bill size and shape; and feather coloration and patterning that can help separate these small “peeps.” 

Note: The visual comparison concentrates on the least and western sandpipers to help fledgling birders recognize key identification features, but the third “peep,” the semipalmated sandpiper, has been included in the written descriptions to better represent the identification challenges birders may experience while in the field. 

Find tips for identifying Oklahoma’s look-alike species in our video series on YouTube.

Similarities: Along with the semipalmated sandpiper, the least and western sandpipers are part of a trio of small sandpipers that often form mixed flocks during migration and spend the bulk of their time while in Oklahoma feeding on mudflats. Their small size, similar appearance, and close association has led to the collective nickname of “peeps” among many birders. 

With their assortment of tan, dark brown, and even reddish head and back feathers, these bluebird-sized shorebirds easily blend into the muddy shores of shallow wetlands. They have white bellies and when in flight, their bent wings reveal a thin white strip on the top of the wing. All three peep species nest on the tundra and only migrate through Oklahoma. Spring migration typically occurs in April and May while the fall migration may occur as early as July and August. To fuel the remainder of their migration, they probe the mud for invertebrates like small crustaceans, insect larvae, and worms. 

Differences: These look-alike shorebirds can be differentiated with a close look at leg coloration; bill size and shape; and feather coloration and patterning: 

• Black or Non-Black Legs? The semipalmated and western sandpipers have black legs while the least sandpiper has yellow-green legs, which can appear darker in color if covered in mud. Because these muddied legs may not appear yellow or greenish, some experienced birders instead refer to the least sandpiper as having “non-black” legs.   
• Progressively Droopy Bills: The semipalmated sandpiper can be distinguished from other peeps by its relatively straight, stout bill. The least sandpiper has a more tapered bill that has a slight droop. The western sandpiper has the stoutest and most drooped bill of the trio, which also appears swollen at the tip. 
• Where are the Rufous Feathers? Peeps can migrate through Oklahoma in various stages of feather replacement or molts, which can add to the confusion of these three sandpipers. In general, the semipalmated sandpiper has the least amount of rufous feathers of the peeps, while the western sandpiper has more red on the head and upper wings during the breeding season. The western sandpiper also has more spotting on the chest and flanks. In contrast, the least sandpiper has the most continuous rufous-brown feathers on the head, body, and throat during the breeding season. All three species are more uniformly gray during the nonbreeding season. 
• Nesting Grounds: The least and semipalmated sandpipers travel to the Alaskan and Canadian tundra to breed, while the western sandpiper primarily breeds in coastal areas in northwestern Alaska and is the least common of the three species in Oklahoma. 

If you see a migrating sandpiper or other shorebird while exploring Outdoor Oklahoma, consider sharing the sighting on free nature platforms like eBird and iNaturalist. Adding a photo to your observation can allow others to help confirm the identification.