Aves | Ciconiiformes
Gaydos, J.K. and S.F. Pearson. 2011. (Ref. 93905)
Size / Weight / Age
max. published weight: 45.00 g (Ref. 87784)
Climate / Range
Indo-Pacific and Atlantic Ocean.
Small (ca. 20 cm long, <45 g); brightly colored during breeding season; while at sea, wear counter shade coloring of white underparts, tail, neck and face, gray mantle, and black eyepatches; laterally-flattened legs, lobed feet, and exceptionally waterproofed plumage (heavy at belly and breast) modified for aquatic life (Ref. 87784). Shorebird species that inhabit oceanic waters up to 75% of the time. Spend up to 9 months of the year swimming on the open ocean. Body modified for aquatic life; surface swimmers by paddling. Pelagic. Attracted to the feeding activity of forging gray whales (Eschrichtius robustus) in the Bering Sea where they feed on mud plumes from disturbed sediments that rise to the surface; several species of benthic amphipods are eaten that would normally not be found on surface waters. Feeds on almost anything found on the water surface that is small enough to ingest, including crustaceans, hydrozoans, molluscs, polychaetes, gastropods, insects, small fish, fish eggs, seeds, sand, and plastic particles; mainly planktivorous; at sea, specialize on copepods, euphausiids, and amphipods < 6mm x 3 mm. Draws prey to the surface with feverish, toy-like spinning behavior; spinning can draw water up to the surface from 0.5 m depth. Peck rates as high as 180/min. In the Gulf Steam off the east coast of North America, small numbers found at floating mats of the marine algae, Sargassum where they feed on associated zooplankton. Califonia Current off western North America, the Humboldt Current off western South America, and the Benguela Current off West Africa are important foraging areas. Feed at convergences, drift lines, fronts, slicks, thermal gradients, and upwellings where food is concentrated on the surface. Flocks at these feeding areas was recorded at an estimated high of 2 to 3 million migratory individuals at a single upwelling near Mount Desert Rock off the coast of Maine, NW Atlantic. Migration follow inland routes southward through central Canada and the western United States, then westward and southwestward to the Pacific where they join Red Phalaropes (Phalaropus fulicarius) heading south offshore from British Columbia to South America. Winters off the western coast of South America; most in this area of the Pacific congregate by the Humboldt Current. European and western Siberian breeding populations migrate through Caspian Sea, over Russia and Iran, through Gulf of Oman and unto the Arabian Sea where they winter. Circumpolar breeding distributions in the subarctic and Arctic, and generally only breed ashore. From Nearctic breeding populations flocks in the western Bay of Fundy; movements south from there and their wintering destinations still poorly known. Found in the Galapagos Is., and as far south as southern tip of Chile; but absent from waters of Galapagos Is. during ENSO event of 1982-1983 that impacted distribution and abundance (Ref. 87784).
IUCN Red List Status (Ref. 114614)
CITES status (Ref. 94142)
Threat to humans
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Estimation of some characteristics with mathematical models