. Bulletin - United States National Museum. Science. BIRDS OF NORTH AND MIDDLE AMERICA FALCO RUSTICOLUS OBSOLETUS Gmelin American Gtrfalcon 633 Adult (sexes alike).—White phase: Extremely variable, but gener- ally the birds fall into one of two types: a. Bar-tailed variety: Entire head, body, wings, and tail white, usually with a faint creamy tinge, the top of the head with narrow chaetura black shaft stripes, these broadening into tear-shaped subtcrminal spots on the nape; interscapulars, scapulars, upper wing coverts, back, rump, upper tail coverts, remiges, and rectrices broadly barred with
. Bulletin - United States National Museum. Science. BIRDS OF NORTH AND MIDDLE AMERICA FALCO RUSTICOLUS OBSOLETUS Gmelin American Gtrfalcon 633 Adult (sexes alike).—White phase: Extremely variable, but gener- ally the birds fall into one of two types: a. Bar-tailed variety: Entire head, body, wings, and tail white, usually with a faint creamy tinge, the top of the head with narrow chaetura black shaft stripes, these broadening into tear-shaped subtcrminal spots on the nape; interscapulars, scapulars, upper wing coverts, back, rump, upper tail coverts, remiges, and rectrices broadly barred with dark sepia to chaetura drab or even chaetura black, only the subterminal dark band visible on the scapulars; interscapulars and upper wing coverts, often somewhat broadly crescentic in shape;. Figure 46.—Falco (Hierofalco) rusiicolus. the bars on the rump and upper tail coverts narrower; the primaries with broad chaetm-a black apical areas very narrowly edged with white, the dark bars disappearing on the inner webs, which are largely immaculate white; the fourth primary (from outside) shorter than the outermost one; median pair of rectrices with both webs crossed by 9 to 11 dark bars (about 10 mm. broad), the other pairs with the bars chiefly on the outer webs and becoming reduced in size to spots and in number as well on the outermost tail feathers; lores and cheeks and auriculars with some fine dusky shaft streaks; chin, thi'oat, breast, and middle of abdomen either immaculate white or with a few small tear-shaped spots of chaetura di-ab on the breast and abdomen; sides and flanks similar to breast and abdomen; thighs either flecked or immaculate white; under tail coverts usually un-. 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 United States National Museum; Smithsonian Institution; United States.
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