Ardea
Official journal of the Netherlands Ornithologists' Union

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Fjeldsa J. (1986) Feeding ecology and possible life history tactics of the Hooded Grebe Podiceps gallardoi. ARDEA 74 (1): 40-58
The Hooded Grebe Podiceps gallardoi discovered in 1974 in southern Argentina has its core area on the windswept Andean foothills at 47-49ŽS, with small, maybe temporary colonies southwards to 500 30'S. The population is estimated to 5,000 birds. The environment is extreme for a grebe and the reproductive success exceedingly poor. The study aimed at an explanation of the peculiar habitat selection and breeding biology. The species is specialized on snails for food, and is thus well isolated, ecologically, from the related Silvery Grebe P. occipitalis. The structure of the submergent vegetation in the breeding lakes leads to area-concentrated feeding, whereby the grebes, after some time, manage to deplete the supply of readily available, optimal food items. Under these circumstances, the pairs often fail in nourishing their single chicks. However, mobility, a surplus of potential breeding lakes, and a rich supply of productive feeding habitat apparently provide for sufficient longevity and life-time production. The Hooded Grebe appears, by its bet-hedging life strategy, to be well adapted to its narrow feeding niche and harsh environment.


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