Regulation of numbers in the Great tit (Aves: Passeriformes)

Authors

  • John R. Krebs

    1. Department of Zoology, Animal Behaviour Research Group and Edward Grey Institute of Field Ornithology, Botanic Garden, High Street, Oxford
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    • *Department of Zoology, University of British Columbia, Vancouver 8, Canada


Abstract

The census data of the Great tit collected by Perrins (1965) and others in Marley Wood near Oxford are analysed for density-dependence. Clutch size and hatching success are density-dependent and sufficiently so to regulate the population at the observed level (assuming that there is in addition a fairly large density-independent mortality). There may also be some weak density-dependent mortality outside the breeding season. The density-dependent variations in clutch size are probably in the main due to shortage of available food and density-dependent hatching failure is caused by predation. Territorial behaviour has been shown experimentally to determine breeding density, and may produce a density-dependent effect outside the breeding season. These three factors are responsible for regulation of the Great tit population in Marley Wood.

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