The Sequence of Plumages of the Rook, With Special Reference to the Moult of the ” Face.”

Published on 01 May 1963 in Main articles

I T has always been a disputed point as to whether the Rook (Oorvus f. frugihgus) gets its bare ” face ” by means of abrasion of the feathers or by a moult. Most ornithologists have favoured the moult theory or have regarded it as a ” natural peculiarity.” This conclusion has been reached, however, by inference rather than by actual experiment. A few somewhat trivial experiments have been made with captive birds, but no proper investigation of the subject has hitherto been undertaken so far as I am aware. Waterton (Essays on Natural History, First Series, 1838) appears to have thought that he had solved the problem when the feathers on the face of a young Rook, kept in a cage by a keeper, began to fall out in the middle of August. Unfortunately the bird met with a fatal accident at the end of August, so t h a t although Waterton had good reason for saying ” that the feathers fall off from the root of the Rook’s bill, by the order of nature,” he did not realize t h a t had the bird lived a little longer new feathers would have grown ” by the order of nature,” and that the bird would have had a fully-feathered face as part of its first winter-plumage. Knox (Zoologist, 1844, pp. 628-33) made a closer investigation, but for want of sufficient care he also eame to wrong conclusions. He kept young Rooks in captivity and found that they

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