Sandpipers

Sandpipers are a varied group of shore birds in the family Scolopacidae, order Charadriiformes. The 85 species in this family include the sandpipers, curlews, snipes, woodcocks, godwits, dowitchers, turnstones, and phalaropes. With the exception of Antarctica, this family occurs worldwide. Thirty-seven species in the sandpiper family breed regularly in North America. The smaller species of sandpipers and the closely related plovers (family Charadriidae) are commonly known as "peeps" to bird watchers, because of their high pitched vocalizations.

It is difficult to describe a "typical" sandpiper. Members of this family vary greatly in body size and shape, for example, ranging from 5 to 24 in (13-61 cm) in body length, with either short or long legs, a beak that is straight, curves upward, or curves downward, and a neck that is either long or short. There are also great variations in color and behavior within this group of birds. Because of the enormous variations between species, the sandpiper family is extremely interesting, but difficult to concisely define.

Most sandpipers feed actively, by walking and running in search of small invertebrates. Most sandpipers typically feed by poking their bill into soft mud or soil, probing for invertebrates, or the birds pick invertebrates from the surface of the substrate or from debris. However, the two species of turnstone, including the ruddy turnstone (Arenaria interpres) of North America and Eurasia, feed uniquely by turning over small stones and beach debris, searching for crustaceans hiding beneath. Curlews, such as the whimbrel (Numenius phaeopus), often eat berries in addition to invertebrates.

A red-backed sandpiper (Calidris alpina) at the Ottawa National Wildlife Refuge, Ohio. This bird feeds by probing or rapidly "stitching" with its bill (like the needle of a sewing machine), leaving a line of tiny holes in the mud. Photograph by Robert J. Huffman. Field Mark Publications. Reproduced by permission.

Most sandpipers nest on the ground, usually making an open scrape that is well camouflaged by its surroundings and difficult to locate. When predators or humans are close to the nest, many sandpipers will exhibit a distraction display, calling vociferously, running nearby on the ground, and sometimes feigning a broken wing, all the while attempting to lure the intruder safely away from the nest. Sandpiper chicks are precocial. That is, they can leave their nest within hours of hatching, and they roam and feed under the close attention of their parents.

Many species of sandpipers, especially the larger ones, breed monogamously as solitary pairs, which often aggressively defend their territory against intruders of the same species. However, some species of sandpiper have a polyandrous breeding system, in which a female mates with one or several males, leaving them with eggs to incubate and care for, while she lays another clutch to incubate and care for by herself. In phalaropes, such as the red-necked phalarope (Phalaropus lobatus) of North America and Eurasia, it is the female that is relatively brightly colored, and who courts the plainer-colored male, who then incubates the eggs and rears the young. This represents a reversal of the usual roles of the sexes. The ruff (Philomachus pugnax) of Eurasia has an unusual, promiscuous courtship and breeding system called lekking, in which the male birds (called ruffs) exhibit a remarkable array of "ear" and "collar" feathers of differing shapes and colors. These are displayed erect to each other and to females (called reeves) during a frenzied, communal courtship at a designated arena.

Depending on the species, the appropriate habitat of members in the sandpiper family may be shorelines, mudflats, wetlands, prairies, tundra, or fields. However, most species in this family breed at relatively high latitudes of the Northern Hemisphere, with some species occurring to the very limits of land on northern Greenland and Ellesmere Island. Sandpipers that breed at high latitudes undertake long-distance migrations between their breeding and wintering ranges. The most accomplished migrant is the surfbird (Aphriza virgata), which breeds in mountain tundra in central Alaska, and winters on the Pacific Coast as far south as Tierra del Fuego at the southern tip of South America. Other extreme cases are the red knot (Calidris canutus) and the sanderling (Calidris alba), which breed in the High Arctic of North America (and Eurasia) but winter on the coasts of northern South America and Central America.

Other species are more temperate in at least part of their breeding range, such as the American woodcock (Philohela minor) of the eastern United States and southeastern Canada, and the spotted sandpiper (Actitis macularia) of temperate and boreal North America. Only a few species breed in the tropics. For example, the East Indian woodcock (Scolopax saturata), closely related to the Eurasian woodcock (S. rusticolla), ranges from South Asia to New Guinea. Only a few species of sandpipers are exclusively of the Southern Hemisphere. These include the New Zealand snipe (Coenocorypha aucklandica), breeding on a few islands in the vicinity of New Zealand, and the Tuamotu sandpiper (Aechmorhynchus cancellatus) of the Tuamotu Archipelago of the South Pacific Ocean.

Some species of sandpiper are rare and endangered. In North America, the Eskimo curlew (Numenius borealis) is perilously endangered because of overhunting. The last observed nest of this species was in 1866, but there have been a number of sightings of Eskimo curlews in recent decades, so it appears that the species is not extinct, although it is critically endangered. Another North American species, Cooper's sandpiper (Pisobia cooperi), apparently became extinct in 1833 because of overhunting. Other than its size and taste, virtually nothing was learned about this species before it disappeared.

During their migrations, certain species of sandpipers are highly social, sometimes occurring in huge flocks of their own species, often mixed with similar sized sandpipers and plovers. For example, semipalmated sandpipers (Calidris pusilla) aggregate in individual flocks of hundreds of thousands of individuals when they stage in the Bay of Fundy of eastern Canada during their southward migration. This is a critical habitat for these and other shore birds, because they must "fatten up" on the large populations of amphipods in tidal mudflats of the Bay of Fundy, in preparation for the arduous, usually non-stop flight to the wintering habitats of the coasts of Central America, the Caribbean, and northern South America.

Most species of sandpipers occur predictably in large flocks in particular places and seasons, especially in their staging habitats during migration and on the wintering grounds. Sandpipers and associated shore birds are highly vulnerable at these times and places to both excessive hunting and habitat loss. These sorts of habitats are absolutely critical to the survival of these species, and they must be preserved in their natural condition if sandpipers and associated wildlife are to survive.