The Ruddy Turnstone is one of the most conspicuous migratory coastal birds that pass through the Pacific coast of Costa Rica. Their plumage is fairly colorful, with white underparts, orange legs, wings that are patched in orange and black, black throat and gray head with black markings. This is true of breeding adult males, but also of females and juveniles, although with streaked face and throat instead of black. Juveniles are duller, but not easily confused with other sandpiper species, as they are generally bigger and their body shape is different.
The Lesser Yellowlegs is a coastal bird, very similar to the Greater Yellowlegs, albeit smaller as one would expect. Telling one apart from the other is difficult, as the size difference may not be apparent if both species are not close by. Both have long, bright yellow legs, with white underparts and mottled gray upperparts, which turn brownish during the non-breeding season. The bill is long and slender, mostly black, although non-breeding adults may show a very small basal portion that’s colored in yellow.
The Whimbrel is a mid-sized coastal bird with a relatively down curved, long bill. Its body is grayish brown with a mottled appearance, where some of the subspecies having a white back and rump. Its call is a high-pitched whistle. They appear very similar to the Curlews, however those species are much larger in comparison. They forage in the shallow waters along the coast, grabbing small invertebrates and crabs from the surface.
The Semipalmated Plover is a small migratory bird that can be spotted in early September at the Pacific Coast of Costa Rica. The upperparts are gray-brown, with a white collar around the neck, white forehead, black mask on the face and small bill with orange basal half and black tip. The underparts are mostly white, except for a black breast band. The delicate legs are orange. It looks very similar to the bigger Killdeer. They wade in beaches and shallow mud flats where they can grab crabs and small insects.
The American Oystercatcher is the only species that reaches Costa Rica, out of 12 species that compose the family Oystercatcher family. They are all very similar, mainly varying in terms of their plumage color. The American species has a brown-gray back, white underparts, pink legs and black head. The eye is yellow with surrounding orange orbital skin, and the bill is large and slim, orange in coloration, which is used to grab and eat shellfish. The inner plumage of the wing is also white, and is shown during flight, or also during displays when wading in the shallow water.
Due to their peculiar look, they are easy to identify among flocks of migratory birds, which normally are composed of gulls, terns, plovers and sandpipers, but are not as abundant during migration and any of those families. They are among the largest of such migratory bird groups. They prefer mud and salt flats that are exposed and shallow, where they can wade to grab prey. They feed by either severing the muscles that enable the mollusks to close tight, hereby getting the meaty interior out, or by grabbing the entire body with the shell, and hitting it against rocks to slam it open.
Most Sandpiper species are pretty similar, specially as they come to Costa Rica in non-breeding plumage. Having a few different species mixed up in a single group can help for identification, as some of them will be showing the breeding plumage that distinguishes them, as well as other features like leg color. In this case, the Least Sandpiper has yellow legs, distinguishing it from the very similar Semipalmated Sandpiper. Also this bird is similar to the Pectoral Sandpiper, however the Pectoral is a lot bigger, has a yellowish bill, and the breast is streaked and delineated vs the white belly.