Abstract
THE precise line—if there be one—marking the distribution between the breeding areas of Corvus cornix and C. corone is of little importance to the “problem” suggested to the readers of NATURE in the review mentioned. Its direction, however, was taken from Newton's trustworthy “Dictionary of Birds,” p. 117, where it is stated to be “an irregular line drawn diagonally from about the Firth of Clyde to the head of the Adriatic.” The reviewer cited that statement as authoritative, since he has had no opportunity of personal observation on the subject. It is further stated on the page last cited, “it has now been incontestably proved that along or near the boundary where these two birds march, they not infrequently interbreed, and it is believed that the hybrids which sometimes wholly resemble—italics by the reviewer—one or other of the parents … pair indiscriminately among themselves or with the pure stock.” If these be established facts, then the hybrid wholly resembling the black variety must, if it occur in any considerable numbers, retire to breed “to the south-western part of this quarter of the globe,” and the hybrid wholly resembling the “grey neck” “to the north-eastern portion.” How has this discrimination been acquired? Two further questions may be asked: Can the wholly black and wholly grey hybrids be recognised after they have left the nest? Can the proportion of pure breeds to hybrids in the general crow-population be determined?
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Distribution of the Forms of Corvus cornix and C. corone. Nature 74, 175 (1906). https://doi.org/10.1038/074175c0
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DOI: https://doi.org/10.1038/074175c0
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