. The Auk. Birds. Vol. XXXVIII 1920 J Allen, Pattern Development in Teal. 561 does each spotted individual differ in the extent of its pigmented areas, but corresponding areas of opposite sides vary in the amount of reduction in the same individual, so that often the contiguous patches of one side may show a white break between them, while those of the opposite side retain Figure 2.—Head of Blue-winged Teal, to show pattern. In this and the other heads, the approximate outline of crown patch and the boundary between ear and neck patches, are shown by a heavier dotted line. Figure 3.—
. The Auk. Birds. Vol. XXXVIII 1920 J Allen, Pattern Development in Teal. 561 does each spotted individual differ in the extent of its pigmented areas, but corresponding areas of opposite sides vary in the amount of reduction in the same individual, so that often the contiguous patches of one side may show a white break between them, while those of the opposite side retain Figure 2.—Head of Blue-winged Teal, to show pattern. In this and the other heads, the approximate outline of crown patch and the boundary between ear and neck patches, are shown by a heavier dotted line. Figure 3.—Head of Southern Teal, showing extension of white pattern through restriction of ear patch dorsally and posteriorly. Figure 4.—Andaman Teal (Polionetta albigularis) showing slight re- duction of ear patch. Figure 5.—White-cheeked Andaman Teal (P. a. leucopareus) showing incomplete formation of a white collar by failure of ear patch to meet the upper end of neck patch. But to return to the Teal, the point of interest is that the white crescentic mark of the normal bird is due according to this view, to a restriction of the ear patch (whose ultimate center is the aural region) at its front end, so that a pigmentless area is left at the base of the bill (Fig. 2). The head pattern of the common Blue-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original American Ornithologists' Union. Washington, D. C. : American Ornithologists' Union, etc.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbirds, bookyear1884
