QJilF iiarblrr 7 



ular difficulty in picking out Parula and Blue-winged Warblers among the 

 foliage. Ordinarily when yellows add to the beauty of the adult male's 

 plumage, they are also possessed, somewhat modified, to be sure, by females 

 and young 5 . Perhaps the best illustration is the strongly yellow Blue-winged 

 Warbler, which holds its yellow color through the different ages and sexes. 

 We find in various species of Warblers certain small definitely shaped 

 markings, the chief value of which is doubtless for recognition. Though 

 sometimes subdued, they hold their character well through the duller as 

 well as the brighter plumages of the species, which would be expected, as 

 these are the least easily recognized from their general appearance. The 

 markings referred to are in the main conspicuous in nature, though not 

 overly so, and often are placed where they are hidden except when the bird 

 is in motion or displays them by its attitude. The writer would classify 

 as recognition marks, the face marks of Prairie Warbler and Blue-wing ; the 

 yellow in tail of the Yellow, yellow rump of the Myrtle, and yellow face 

 of the Black-throated Green Warblers, the white basal tail band of the 

 Magnolia Warbler, white sides of the Hooded Warbler's tail, and white 

 check in the wing of the Black-throated Blue ; the yellow eye-ring of the 

 Canadian Warbler and cloven yellow base of the Redstart's tail. 



Three of our species, the Ovenbird, Northern and Louisiana Water- 

 thrushes, have a thrush-like plumage. It is significant that these feed on 

 the ground in the shade like the thrushes. Probably their type of plumage 

 is particuliarly adapted to conceal its wearer. The bobbirg tail of the 

 Water-thrush which renders that bird conspicuous in spite of its highlv con- 

 cealing plumage, has in the writer's opinion a purposefully advertising func- 

 tion, like the incessant calling of certain concealingly colored Mammals. 6 



One of the most familiar species, the Black and White Warbler, has 

 an almost Woodpecker-like habit of clinging to tree trunks and branches. It 

 is interesting that this is also the species which has the black and white 

 Woodpecker color, good evidence that there is a correlation between the 

 color and habit, but what is the correlation? Concealing coloration will not 

 explain it. From a man's eye view a black and white bird on a tree trunk 

 is decidedly conspicuous, and it is not so much the white underparts, which 

 would be seen by an insect, and which are common enough in birds, but the 

 black and white upper parts which we are trying to explain. Recognition 

 does not seem an adequate explanation when we consider that a similar 

 plumage is possessed by the Woodpeckers. The plumage display is made 

 to appear improbable by the plumage being possessed little changed in both 

 sexes and in the young. It is of course possible to fall back upon the un- 

 satisfactory theory that the color is determined by special, tree-trunk food, 



5. The yellow crowns of the Chestnut-sided and Golden-winged Warblers are an exception. 



6. 1912. Nichols, J. T. The Auk. Vol XXIX p. 48. 



