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Ontogeny of behaviour in five species of grebes.

University of British Columbia

The resting postures, locomotion, feeding behaviour, and comfort movements of five species of grebes (Podiceps caspicus, P. auritus, P. grisegena, Podilymbus podiceps, and Aechmophorus occidentalis) are described, compared, and their development traced to the adult form. Each pattern is then compared with its counterpart in other groups of birds, and its adaptive significance is considered. In defecation, climbing-up, and begging the eliciting stimuli are examined. The stages of development are traced, and it is found that the birds hatch at the beginning of stage two, the first appearance of comfort movements. They pass into stage three, the maturation of comfort movements, within a few hours and remain in this stage until the adult sleep posture is assumed, functional preening and oiling are established, and spontaneous swimming appears, at eight days. Stage four includes the appearance of simple bathing, diving, and the substitution of following for riding on the parent’s back. Stage five, beginning about the sixteenth day includes matured bathing, alarm, self-feeding, and finally flight. Because of the great increase in length of stage three over that of precocial birds, the inability of the chicks to maintain the adult sleep posture, the lack of functional preening and oiling, and the depression of all activity, it is suggested that the grebes be considered not precocial birds but semi-precocial birds with the gulls. They are adapted by these attributes and by the controlled defecation response to life in a nest. The grebe nest being unsuitable for prolonged brooding, the grebe broods its chicks on its back.

Text

2011-11-08

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http://hdl.handle.net/2429/38870

Zoology

University of British Columbia

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