Although neither species of North American curlew is common, the most abundant ones are the long-billed curlew (Numenius americanus) and the whimbre, or Hudsonian curlew (N. phaeopus). The long-billed curlew breeds in wet meadows and grassy habitats in the western United States and southwestern Canada, and winters on mud flats and beaches in southern California and parts of the Gulf of Mexico. This species appears to be declining in abundance, likely as a result of the loss of most of its natural habitat, and possibly because of damage caused by pesticides.
The whimbrel breeds further to the north in two sub-arctic populations, one in coastal Alaska and northwestern Canada, and the other around the west coast of Hudson Bay. The whimbrel also breeds in northern Eurasia. The winter range of this species is very broad, ranging from the southern coastal United States, to the coasts of Central and South America, and some Pacific islands.
The bristle-thighed curlew (N. tahitiensis) is a rare species with a total population of fewer than 10,000 individuals. The bristle-thighed curlew breeds in montane habitat in western Alaska, and migrates directly south, to winter on widely scattered islands of the Pacific Ocean, including the Hawaiian Islands. The 5,000–5,600 mi (8,000–9,000 km) migration of this species is an extraordinary feat of non-stop flight while navigating over trackless water, in search of its scattered wintering islands.
The Eskimo curlew (N. borealis) is the smallest of the North American species, only 11 in (28 cm) in body length. This species was once abundant during its migrations. However, the Eskimo curlew was decimated by market hunting during the nineteenth century, and is now exceedingly rare, and on the verge of extinction (in fact, some biologists believe it is already extinct). The Eskimo curlew is one of many examples of once abundant species that have become extinct or endangered as a result of uncontrolled, unscrupulous exploitation by humans. Such tragedies represent lessons to be learned, so that similar calamities of biodiversity can be avoided in the future.