Anpassungen der Eier und des Brutverhaltens von Trottellummen (Uria aalge aalgePont.) an das Brüten auf Felssimsen*

Authors

  • Dr. Paul Ingold

    Corresponding author
    1. Zoologisches Institut der Universität Bern, Ethologische Station Hasli
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      Mit der Unterstützung des Schweizerischen Nationalfonds zur Förderung der wissenschaftlichen Forschung.


  • *

    Beat Tschanz gewidmet.

Ethologische Station Hasli, Wohlenstraße 50a, CH-3032 Hinterkappelen/Bern.

Abstract

A comparative, descriptive and experimental investigation on Guillemots and Razorbills on Vedoy (63° 30′ N 12° E) was undertaken to discover how an egg characteristic (shape) together with behavioural characteristics enable Guillemots to incubate their egg on the bare surface of a cliff-ledge where it is in danger of falling off. Laboratory ad field experiments with several hundred eggs showed that the pear-shape evidently protects an egg that is rolling away from the nesting-site from falling off: Though Guillemot eggs do not stay on the ledges better than Razorbill eggs, they would — due to their higher weight — be in greater danger of falling off if they had the shape typical of a Razorbill egg. Observations on incubating Guillemots and Rezorbills plus an field experiment showed that Guillemots are distinguished by several behavioural characteristics by which they very strongly reduce the risk of an egg rolling away at all.

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