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Show SPEAKING OF BIRDSTj O There's really no blue or green in tle'u feathers, but sun rays, rain or a blUe SU can make our nesting friends colorful as t peacock! ! Prepared by National Geographic Society, PF Washington, D. C.-WNU Service. THERE is no blue pigment pig-ment in the feathers of birds; neither, with rare exceptions, is there any-green. any-green. The only pigment colors in ordinary birds' feathers are reds and yellows and blacks, and all the other colors are due either to a combination of these or to the superficial structure of the feathers overlying some other pigment. Blue feathers, for example, contain only brown or blackish black-ish pigment overlaid by a Layer of prismatic cells which reflect only blue light rays. Sometimes the structure is that of minute pits on the surface of the feathers. When they become filled with water during a rain, they lose their refractive power, and the birds, apparently, change from blue to white, as in the tropical swallow tanagers. Again, the blue color is due to minute air spaces in the superficial layer of cells, just as the blueness of the sky is due to minute dust particles, and the blueness of the milk on the boarding house table to the minute cream droplets. So long ules, are gray. As these taarhm V wear off, the barbs with thS ' become more exposed and the fe! ers apparently get brighter tZ W the red finches (the purple fl house finch, and redpolls) appa7 , X Thus the summer tanager m remains red throughout the v7 i and so do the cardinal, the tur 1 finch, the pine grosbeak, and J! ' crossbills. The yellow evening" -beak never becomes gray i&e C mate, once he has acquired matin ty though the male goldfinch do.' No one has yet advanced i BaU mu'01 factory explanation for these diff. "s 1 ences In seasonal styles amons males, but the inference is that U Vin females are dully colored so as n 0 li to attract attention to the nest Us ally the brilliantly colored males -it Bi this family never assist in Incubi'iolt1 ing the eggs, but even here thaws' are exceptions, as in the roiV breasted and black-headed beaks. Males of these birds nncf only sit on the eggs, but even bre( ; 0Jib: all rules of bird conduct by sinEii' r;ih as they do so. j jjso Grosbeak Mortality lW Whether because of the singln' or because of the bright colors I 1 the incubating male, or because M the general fragility of the nes there is a relatively high nest mo Vfll tality among the rose-breasted gro'-'1' beaks, and some years very fj .0t I txJVv X)sG as our blue birds remain between us and the source of light, they are not blue birds at all and therefore may go unnoticed. Yellow birds are usually conspicuous conspicu-ous because our eyes are very sensitive sen-sitive to yellow. But many birds have a blue-producing structure overlaid by a yellow pigment, so that the combination sends green light to our eyes. Then we say these birds are green. Wet the back of a parrot and it becomes brown, or scratch the surface of one of the green feathers with a knife and a dark mark is left.' This is not because any green pigment is scratched off, but because the yellow yel-low and the prismatic cells have been removed and the dark layer beneath exposed. But there seem to be many red birds among these tanagers and finches. Why do we not see them more often? Certainly we have no trouble seeing a red traffic light indeed, most of them seem to be that color when we are in a hurry. There are some reds, such as the iridescent throats of the humming birds, for which the structure of the feathers is responsible. But most reds, such as those of the tanagers and finches, are due to pigment, and they register as red under all light conditions. To be really effective, effec-tive, however, the red must be exposed ex-posed to direct sunlight. Should a scarlet tanager alight in the middle of a sunlit lawn or a cardinal fly across the open space in a garden, either bird would attract at-tract attention, but most of the time they are sitting among the shadows of green leaves, where they are poorly lighted. The sunlight is reflected re-flected from the leaves more readily than from the birds, especially since our eyes are peculiarly sensitive to greens. Winter Markings During the winter many birds have their conspicuous marks veiled by gray edges to the feathers. These edges break off during the spring, exposing the color underneath. The male house sparrow, for example, in winter seems to have only a narrow nar-row line of black on his throat, because be-cause the rest of his black cravat is concealed by the gray tips of the feathers, which break in April. Red finches display no such gray edges to the feathers. But upon examining ex-amining a feather with a lens, one will find that the red pigment occurs oc-curs only in the main branches of the leaflike structure, the parts called the shaft and the barbs, while the more minute branches, or barb- For their nest in the wei ,,.e a pair of enterprising L( .el Angeles sparrows selected atk electric switch box which ft ar owner immediately shut off I a. prevent electrocution, Tu a'iiu fledglings are shoien above, krclL their novel nest. i ; young ar reared. Then the sp cies becomes scarce, because gro j beaks are not so persistent aboiJlPJl renesting as are some other birdi There is no one place in Norl America where all of the birds her -mentioned can be found. The pyr, huloxia, hepatic tanager, beautifi 3 bunting, and Sharpe's seedeater, fc , example, are not found very l : north of the Mexican border. j The lazuli bunting, black-heade grosbeak, western tanager, ros finch, house finch, green-backed an Lawrence's goldfinches are birds n; the Pacific coast and the Rockj fj mountain region, while tie rost breasted grosbeak, scarlet tanagei j -and indigo bunting are prlmaril j birds of the eastern United States., . It is difficult to explain why eac species has a restricted summev home when it is free to come and 1 as it pleases and often migrates el tensively. It is still more dif to explain how this whole group birds got into North America ongi; nally. Certain of them, such ata tanagers, the cardinals, the iW rose-breasted, and black-heade grosbeaks, and the "buntings, h" close relatives in Central and SMB America and none in the Old wort Hence, we feel that our Wa', came originally from the soutn, 1 " ( |