Monday, April 16, 2012

Long-Billed Curlews

While crossing the stormy Plains yesterday afternoon, I encountered a small flock of long-billed curlews, attempting to fly into the teeth of an icy north wind. After wintering along the western Gulf Coast, in South Texas, in Southern California or in Mexico, this largest American shorebird returns to grasslands of the High Plains, Great Basin and Columbia Plateau for the warmer months.

Once on their breeding grounds, couples engage in courtship rituals, including dances, looping flights and preliminary nest site scooping by the male. The female eventually selects one of his open ground sites, engages in additional scooping and collects a variety of plant materials to place in the floor of the depression. Four eggs are deposited and incubated by both parents; like many game birds, the young are able to move about and feed soon after hatching and are attended by both parents for a week or so. Thereafter, the female parent departs to join other wayward mothers and juveniles in large feeding flocks while the father stays to watch over the youngsters until they are fledged. The long, down-curved bill of this curlew is used to probe mudflats, wet meadows and sandy shallows for a variety of invertebrates (worms, insect larvae, shrimp, sand crabs) and small amphibians; they may also snare grasshoppers, crickets and other insects from the grass and occasionally consume the eggs of other prairie birds.

Once common in parts of the Eastern U.S., long-billed curlews have retreated westward due to over-hunting and habitat loss to agriculture; fortunately, the western populations seem to have stabilized but remain sensitive to the health of shortgrass ecosystems. Small numbers of long-billed curlews may turn up on Atlantic beaches during the fall and winter months where they can be distinguished from whimbrels by the curlew's larger size, longer bill and unstriped crown and from the occasional Eurasian curlew by the latter's darker plumage, white rump and heavily streaked breast; the cinnamon wing linings of long-billed curlews also aid identification when this large shorebird is in flight.