6 $ty *farbU>r 



two, and most of their even distant allies, might well have the concealing 

 value of cross marks so ably emphasized by Thayer in arguing for the con- 

 cealing coloration hypothesis. Their absence in species unrelated to these 

 (Maryland Yellow-throat, Canadian Warbler, etc.,) indicates that they have 

 been acquired by the distant common ancestor of the birds in which they 

 occur, and are not a recent response to environment 4 . In certain species 

 they become a white blotch in the high plumaged male which adds to the 

 display of his colors (Magnolia, Cape May, Blackburnian.) 



The resemblance of allied species, which we find between the Water- 

 thrush and Ovenbird, can not be set down as an exception to the rule just 

 brought forward of divergence of primary specific colors in close allies ; as 

 being concealingly colored, they have no true primary specific colors, ex- 

 cepting the crown patch of the Ovenbird, and furthermore resemble a Thrush 

 in color, almost as much as they do one another. The closer resemblance of 

 the two Water-thrushes which have different breeding ranges, however, shows 

 where our rule breaks, namely as regards allied species occupying differ- 

 ent ranges. Several of our species are represented in other parts of the 

 country by allied birds which resemble them in color ; as the Parula by the 

 Sennets, and Black-throated Green by the Golden-cheeked in Texas and 

 Mexico, and the Myrtle by the Audubon's Warbler in the West. 



This would be explainable on the supposition that these species are re- 

 cently derived from geographic races, which almost always are very similarly 

 colored, being only slightly different each from the common parent form. 

 The writer further inclines to the belief that were two such species to come 

 to occupy the same territory, the mutual advantage of dissimilarity would 

 force them apart. 



In general the male Warblers are more highly colored than the females, 

 or than the females and young. Often this high plumage is entirely differ- 

 ent from the others (Blackpoll, Black-throated Blue.) The colors of such 

 high plumaged birds make for conspicuousness, ready recognition and dis- 

 play, and it is most rational to assume that these are their biological func- 

 tions. Such colors are typically blacks (Redstart, head marks of Blackpoll, 

 Golden-wing, Magnolia, Maryland Yellow-throat, Hooded, Wilson's) grays 

 (Black-throated Blue, Myrtle, Magnolia) and reds, as chestnut in streaks, 

 blotches, or larger areas (Yellow, Baybreast, Chestnut-sided, Cape May, 

 Yellow Palm) or as making orange of yellows (Blackburnian, Redstart.) 



Yellows, however conspicuous they make the bird appear in a tray 

 of specimens or on some unwonted exposed perch, are usually incon- 

 spicuous in the field. The writer's eye on diverse occasions has had partic- 



4. It is perfectly true, however that the species without cross marks on the wing are, on the 

 whole much more terrestial or addicted to the lower growth, than those with such marks. And it 

 might readily be argued that these marks have more concealing value to birds of arboreal habits. 



