Phalaropes at sea

William Hamner, Ph.D.
University of California, Los Angeles
Department of Biology

Wednesday, January 28, 1998
3:30 p.m.—Pacific Forum

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Phalarope exhibiting a "spinning," feeding behavior

Phalaropes are quite small shorebirds in the order Charadriiformes, a group that also includes skuas, gulls, terns, and auks. Phalaropes are distinct from other sandpiper-like birds mainly in that they exhibit sex-role reversal, with the female larger and more brightly colored than the male, who incubates and tends the young. Phalaropes, unlike other sandpiper-like birds, have uniquely lobed toes that facilitate swimming and exceptionally dense plumage that traps air and provides buoyancy for swimming.

 There are only three species of phalaropes worldwide: Wilson's phalarope (Phalaropus tricolor), the red-necked phalarope (Phalaropus lobatus), and the red phalarope (Phalaropus fulicarius). Wilson's phalarope is exclusively New World, whereas the other two species are circumpolar. All three are transequatorial migrants that often spend long periods of time in transit and feeding at sea. Little is known about phalaropes at sea, but they often exhibit a behavior called "spinning," associated with feeding. We describe the behavior and hydrodynamics of spinning and feeding in red-necked phalaropes in the laboratory, at Mono Lake, and at sea off southern California. Phalaropes are small sea birds (18-25 cm) with continuous flapping flight, high metabolic rates, and high food requirements. At sea phalaropes cannot survive on background concentrations of forage, but instead they invariably locate and exploit surface aggregations of zooplankton, particularly at fronts and on Langmuir cells. Phalarope feeding locations at sea provide insight into important physical, chemical, and biological oceanographic processes.

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