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Material contained herewith may not be used without the prior written permission of FAUNA Paraguay.
Photographs on this web-site were taken by Paul Smith, Hemme Batjes, Regis Nossent,
Alberto Esquivel, Arne Lesterhuis, José Luis Cartes, Rebecca Zarza and Hugo del Castillo and are used with their permission.
PODICIPEDIDAE - GREBES
Five species of superficially duck-like aquatic birds, one of the oldest known bird families with fossils dating back to 80 million years ago. South America appears to be the centre of radiation and is where the greatest diversity of species occurs. Grebes have an extremely dense, waterproof plumage which is maintained thanks to a well-developed oil gland. They are exclusively aquatic, coming to land only to breed, and are supremely adapted for diving and swimming, the front of the body tapered to cut through the water, and the rear of the body rounded with a vestigial tail to reduce resistance. The skeleton is not pneumatised so they sit low in the water but are able to adjust their buoyancy at will. Prior to diving they exhale, contract the abdominal muscles, sleek the plumage and may jump slightly to increase the angle of the descent. In the water they propel themselves with the flexible legs which are set well-back on the body and also act as a rudder. However this results in clumsy locomotion on land, and the birds come to land only to breed. The tarsi are laterally compressed and the toes are uniquely lobed, being only slightly webbed. The hallux possesses a single small lobe. They fly strongly but rarely, with rapid wing beats of short, rounded wings (12 primaries, 17-22 secondaries). The primaries are curved and the wings are completely concealed by the body plumage at rest. All the flight feathers are moulted simultaneously, resulting in a short period of flightlessness each year. Bill shape and neck length varies greatly amongst species and may be directly correlated to diet and feeding method.
REFERENCES
Campbell B & Lack E 1985 - A Dictionary of Birds - T & AD Poyser.
Llimana F & del Hoyo J 1992 - Podicipedidae Handbook of the Birds of the World Volume 1 - Lynx Ediciones.
Ogilvie M & Rose C 2003 - Grebes of the World - Bruce Coleman.
