CHAPTER XI 



BACKGROUND-PICTURING ON OBLITERATIVELY SHADED BIRDS, CONTINUED. 



'HE duskiness of obliterative shading on such birds as rails, gallinules 



and coots, is in keeping with their habit of skulking under deep marshy 

 cover, closely shaded from the direct top light, and often, momentarily, lighted 

 more from the side than from above. A true obliterative shading exists, how- 

 ever, on almost all the species. Two or three main types of coloration prevail 

 among them, but there is little variation beyond these types, and only such 

 as is consistent with ' obliteration.' The colors of water, much like those 

 worn by herons, predominate among the more aquatic species, the coots and 

 gallinules. Qlive, green, blue, purple, slate-gray, dusky — these are charac- 

 teristic gallinule colors, and likewise the colors of water. A few of the birds 

 that wear them are scantily or not at all counter-shaded. The Purple Galli- 

 nule (Ionomis martinica) for instance, with its bright but softly-blended water 

 tones, is as dark beneath as above, though there is a counter shading from 

 the middle of its back to the lower edge of its folded wing. It lives for the 

 most part over deeply and diversely shaded pools, and amidst the big, glisten- 

 ing leaves of water plants, and its peculiar coloration does certainly achieve 

 adequate 'obliteration.' (This will be explained more fully in a later chap- 

 ter.) It is noteworthy, however, that in almost all cases where the adult 

 plumage of one of these swamp-haunting species lacks obliterative shading, 

 that of the young possesses it in full. This is true not only of the Purple Gal- 

 linule, but in a remarkable degree of some of the jacanas, as the common 

 Jacana jacana of South America. These birds live in tame and noisy flocks 



WATER MARKINGS AND COLORS 



59 



