Bristle-thighed Curlew
Bristle-thighed Curlew
Numenius tahitiensis
At a Glance
A rare and enigmatic bird. It was discovered wintering on South Pacific islands in 1769, but its nesting grounds were not found until almost 180 years later -- in the late 1940s. It is now known to nest in a few hilly areas of western Alaska. During the winter, molting its feathers, it is unable to fly for a time -- the only shorebird known to have a flightless molt. This is no problem on remote islands with no predators, but becomes a serious handicap when humans settle on those islands.
All bird guide text and rangemaps adapted from Lives of North American Birds by Kenn Kaufman© 1996, used by permission of Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Category
Sandpiper-like Birds, Sandpipers
IUCN Status
Vulnerable
Habitat
Tundra and Boreal Habitats
Region
Alaska and The North
Behavior
Direct Flight, Running
Population
10.000
Range & Identification
Migration & Range Maps
After nesting, most individuals gather on the Yukon Delta in western Alaska to feed heavily on berries and insects, building up fat reserves, then depart on nonstop flight of over 2,500 miles to Hawaii and other islands in Pacific.
Description
17" (43 cm). Very much like Whimbrel, but has bright peachy cinnamon rump and tail, visible in flight. When standing, shows somewhat more contrast on upperparts (but fall juvenile Whimbrels can be similar). Voice differs. Long bristles at base of legs are hard to see.
Size
About the size of a Crow, About the size of a Mallard or Herring Gull
Color
Brown, Gray, Tan, White
Wing Shape
Pointed, Tapered
Tail Shape
Rounded, Short, Square-tipped, Wedge-shaped
Songs and Calls
A plaintive drawn-out whistle, too-lee.
Call Pattern
Undulating
Call Type
Whistle
Habitat
Tundra (Alaska); reefs and beaches in winter. Nests at a few sites in western Alaska, well inland in steep hilly country, on open tundra with scattered small shrubs. Winters on islands in tropical Pacific, on beaches, coral reefs, mudflats, grassy fields.
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Behavior
Eggs
Usually 4. Olive-buff, blotched with brown. Incubation is by both sexes, roughly 25 days.
Young
Downy young leave nest soon after hatching, are tended by both parents. Young feed themselves. Adults are very aggressive in defending the nest and young; may put on "distraction display" to lure predators away, or may directly attack even large predators. After a few days, families with young move away from nest site, eventually gathering with other families on hilltops. Adult females usually depart before young fledge, leaving males to care for young.
Feeding Behavior
Forages mostly by walking on ground, picking up items from surface, probably also probing in soil or mud with long bill. In feeding on thick-shelled eggs of albatrosses on winter range, may pick up a piece of rock and use it to crack the shell, a rare case of tool-using by a bird.
Diet
Includes crustaceans, insects, berries. Summer diet not well known, probably includes many insects. In late summer, may feed heavily on berries. On Pacific islands where it winters, feeds on crustaceans, snails, small fish; also eggs of seabirds nesting there.
Nesting
Early in breeding season, male displays by flying over nesting territory, calling. Nest site is on the ground on hilly upland tundra with scattered small shrubs, with nest often placed directly under a dwarf willow. Nest is a shallow depression in tundra, lined with bits of lichen, moss, and leaves.
Climate Vulnerability
Conservation Status
Rare, population probably well under 10,000. Most threats are on wintering range, where the curlews are very vulnerable during the flightless stage of their molt. Sea level rise, driven by climate change, is likely to reduce the available wintering habitat.