Ardea
Official journal of the Netherlands Ornithologists' Union

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Kortlandt A. (1995) Patterns of pair-formation and nest-building in the European Cormorant Phalacrocorax carbo sinensis. ARDEA 83 (1): 11-25
Courtship signals (i.e. the crouching partner in the nest centre and the erect partner outside the centre) are performed by both sexes, except for the male wing-waving. These patterns are derived from the copulatory postures by degenderisation and partly by de-aggressionisation. The role differences between the sexes in copulatory behaviour, territorial defense and individual mate preferences are expressed by aggressive vs. subdued vocalizations and by stiffish vs. supple motions which symbolise dominance vs. submission. The similarity of postures and the soft voices in the tender rubbing, billing and cooing which precede egg-laying, symbolise the equality of the forthcoming parental roles. Copulatory behaviour and pair-forming behaviour ('sex' and 'love') represent etho-physiologically different systems: they are not closely synchronised, have different motivations, operate through different mechanisms and have different aims and feedbacks, even though they mix and interact. Nesting behaviour is organised by a hierarchical system of drives and feedbacks, but the organisation differs between males and females. In males the system acts independently, in females it is subservient to the parental system. Ontogeny and seasonal maturation of nesting behaviour proceed by the isolated development of (sub-)patterns which is followed by their ascending integration. The methodology of interpretation of the observed behaviour is illustrated by recounting a 'true love story' from Cormorant life.


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