THE BREEDING OF SOME S.W. ECUADORIAN BIRDS

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Abstract
SUMMARY: The breeding of about 40 species of birds in the Ancon district of the Guayas Province of S.W. Ecuador is described. The information is based on the records of about 2000 nests observed during 1955–1958. About half the species are birds which range over much of Central and South America and whose breeding has been previously described, though usually casually. For these my own remarks are confined to new information, doubtful points and confirmatory details. The rest are species more or less confined to the west coast of South America between Ecuador and Chile, and for which there is either little or no breeding information in the literature. These are treated under headings of nest site, nest, eggs, clutch‐size, laying, incubation, nestling period, breeding success and season, with general remarks where appropriate. For most species, closely determined incubation and nestling periods arc given, and for some, quantitative data on clutch‐size and breeding success are available. In some species differences have been found for annual mean clutch‐size, mean clutch‐size laid before and after rain, annual breeding success and fledging success, doubtless due to pronounced climatic variation from year to year which either has a direct effect or influences predation.These matters are discussed generally in the introduction, with particular mention of 10‐day incubation periods, the rapid nesting cycle of several finches, precociousness of their young, and comparison of breeding success with that of European species, as well as the peculiar ecological variations of the district and changes in predators.In the sequel the statistical aspect of my data is analysed by Dr. Monte Lloyd and I have followed this with somea posterioriremarks.