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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.
HELIORNITHIDAE - SUNGREBE
One Paraguayan representative of a pantropical family of three species, each in monotypic genera. The biology of the family is extremely poorly known and though there exist no fossils attributed to the group their pantropical distribution suggests an ancient lineage. Skeletal and muscular arrangements suggest they form part of the Gruiformes and they share certain Mallophagian lice and egg-white proteins with the Rallidae. However DNA-DNA hybridisation may reveal a close relationship with the Aramidae. The information presented here applies to the Sungrebe, the only Neotropical representative of the family and the sole member of the subfamily Heliornithinae (the Old World Finfoots belonging to the subfamily Podicinae). The subfamilial distinction is on the basis of the naked altricial young of the Sungrebe compared to the feathered nidifugous young of the finfoots. The family name Heliornithidae is from the Greek meaning "sun bird".
Sungrebes are secretive inhabitants of densely-vegetated waterways where they are easily-overlooked. The head and neck are elongated with a sharply-pointed bill and the body slender. Legs brightly-coloured with lobed toes. Lobed feet are an adaptation to aquatic existence providing powerful propulsion but do not hinder movement on land. They swim with exaggerated nodding head movements. Tail is long, graduated but unlike other members of the family the retrices are not stiffened. A claw present on the first digit of each wing is carried into adulthood. Sungrebes are able to control their buoyancy so that they may float high on the water or sink so that just the head remains above the surface, because they lack the waterproof flexules on the tips of the breast feathers present in many other aquatic birds. Diving is rare, the birds feed mainly by picking on the water surface or from vegetation. They are agile and rapid runners on land, scuttling low through thick vegetation to safety. Sungrebes are reluctant to fly but are capable of long flights. Generally they fly low with steady, fast wingbeats and tail fanned, landing on water and immediately clambering up to a resting place on land.
Male sungrebes form territories which are vigorously defended against intruders. They breed during the summer rains, constructing an untidy bowl-like nest in thick vegetation, overhanging water. Both sexes build the nest and incubate the eggs. Incubation period is remarkably short for a bird of its size at 10-11 days. Naked young are carried in "pockets" under the wing by the male. Females are smaller but more brightly-coloured than males.
REFERENCES
Bertram BCR 1996 - Heliornithidae Handbook of the Birds of the World Vol 3 - Lynx Ediciones.
Campbell B & Lack E 1985 - A Dictionary of Birds - T & AD Poyser.
