191 ] Tracy: White Markings in Birds. 307 



top-patterns have decided utilitarian value to high-ranging 

 warblers. That the value of white patterns is at a minimum for 

 ground nesters and low feeders, seems to be as clearly demon- 

 strated. 



For those who find the arguments for the concealing functions 

 of top-white conclusive, the table will primarily serve as evidence 

 of the correctness of Mr. Thayer 's interpretation. And such they 

 are in so far as they corroborate the view that birds often seen 

 against open foliage with sky-illuminated spaces should have and 

 do have bright patches imitating these spaces. There may be 

 no opposing view that can rob this one of its convincing power 

 once it has been perceived. There is, however, a further con- 

 sideration deserving attention. 



High and open foliages involve more than a broken sky 

 and leaf background with the need for imitating them. They 

 involve wider spaces to travel; the ability to see companions at 

 a greater distance; the need of seeing and keeping track of 

 them by other means than call-notes; the long continued habit 

 of so doing. 



The warblers are among the most mutually dependent of 

 birds, the least solitary, migrating in flocks and social during the 

 daytime-portions of their travel. Among the least social the 

 shyest and most retiring of the family are the plain or somber- 

 hued species, including the so-called water thrushes (Seiurus 

 noveboracensis and 8. motacilla) and the Connecticut and mourn- 

 ing warblers (Oporornis agilis and 0. Philadelphia). The bolder, 

 the most familiar, are in the Dendroica group (Dendroica 

 coronata, maculosa, auduboni, etc.). This need not be a mere 

 coincidence. We have noticed the same tendency in the order at 

 large. With a preference for close, leafy coverts and secluded 

 forest ways go the somberer tones, the monochrome coloration, 

 and shy, furtive habits. With a preference for open woods and 

 roving ways, greater distances and separations to be adjusted, 

 have come the greatest variety of top-patterns among birds, 

 many of them showing excellent devices for a revealing flight 

 from the opening wing. 



