tion, its species grade into other classes, not only of forest birds, but of the 

 birds of the open land, the reed swamps, bush swamps, and river banks, where 

 still other systems of coloration come into play. Thus there are 'brush- 

 birds' which have also a liking for spots of bare, open ground, and have ac- 

 quired markings much like those of larks and other field birds of the North, 

 Characteristically, however, they are somewhat boldly mottled, with much 

 black and white and ash color; 'pictures' (to be seen in the dim light of the in- 

 teriors of bushes) of sky vistas overlaced with obstructing, shadowed leaves 

 and branches. Some of those which frequent river banks, like certain Ant- 

 birds of South America, are often marked with the water-shine punctations 

 described in Chapter XI, on a ground-color of muddy gray or brown, oblit- 

 eratively shaded. But the vagaries of this none too sharply defined class 

 cannot be described in detail here. The species which constitute it are less 

 typically birds of the forest than of the brush-lands outside the forest. Nor 

 are they, as a color-class, peculiarly characteristic of the tropics, being scarcely 

 separable from the brush-birds of temperate climes. True, the brown, green 

 and gaudy classes are also represented in northern woodlands, but by no 

 means in such full and special development as they have attained in the teem- 

 ing tropics. 



In the snowy northern winter, on the other hand, where the avifauna is 

 extremely meager, we see special color-adaptation reduced to its simplest 

 terms. The costumes of the few birds which pass the winter in the snowy 

 northern, forests, deciduous or evergreen, are, it is evident, specially fitted 

 to that season of the year. Some of these birds even, like several of the boreal 

 mammals, turn white at the approach of winter, resuming their gray or brown 

 mottled plumage in the spring. Such are the ptarmigans, described in Chap- 

 ter VII. But most of the species either keep the same coloration throughout 

 the year, or merely become somewhat paler and dimmer in the autumn, grad- 

 ually brightening, by the erosion of the feather-tips, through the winter and 

 spring. But even those which do not change color are best equipped for con- 

 cealment in the winter — the dangerous time of leafless woods and keenly 



"3 



