256 



Bird- Lore 



boreal regions; the cock Ostrich and Black 

 and White Chat among desert animals; the 

 skunk, Yellow-headed Blackbird and Lark- 

 bunting of the semi-arid regions of the 

 United States; the Tanagers, Cardinals, and 

 innumerable other birds in the moist 

 temperate parts of North America. More- 

 over the general coloration tendency, 

 where it exists, seems to affect alike birds 

 and mammals which might possibly be 

 benefited by it, and birds and mammals 

 which because of their nocturnal habits or 

 for other reasons cannot possibly receive 

 such benefit. The Eagle Owl of America, 

 for instance, tends to be gray in the semi- 

 arid region, and whitish toward the north; 

 but its habits are such that it is impossible 

 that these slight differences in its color- 

 ation can have any advantageous effect 

 upon the individuals so colored. The 

 same statement applies to the black Duck- 

 hawk of the Puget Sound region. 



"(2) There are certain birds and cer- 

 tain mammals whose coloration is un- 

 questionably concealing, either for most 

 of the time, or at certain vital periods, as 

 when nesting, or, in the case of nocturnal 

 birds, when crouching motionless during 

 the daytime. Nighthawks and many 

 Grouse are striking examples of this. So, 

 to a much less degree, are most rabbits, 

 although these rabbits when in motion 

 have a highl}^ advertising rear-end colora- 

 tion. All these animals deliberately strive 

 to escape observation b}- remaining mo- 

 tionless. The chief factor in enabling them 

 to do so, aside from cover, is their actual 

 tint, whether uniform, or varied, or so 

 minutely varied as to convey at a very 

 short distance an impression of uniform- 

 ity; but in some cases the concealing 

 power of the coloration is probably 

 slightly helped by countershading. These 

 mammals and birds of unquestionably 

 concealing coloration, where the conceal- 

 ing coloration is a principal factor in their 

 concealment, are not man}- in number. 



"(3) Many mammals are advertisingly 

 colored. This is true of many of the 

 dog family, of most of the highly pre- 

 dacious weasel family, of many arboreal 

 squirrels, and of very large numbers of the 



big grass-eating animals. Some of these 

 animals live in the open plain or on high 

 mountains, and are very conspicuous and 

 easy to see. Others live in thick forests, 

 and yet are exactly as hard to see as if 

 they were obliteratively colored, because 

 of their wariness and their ability to take 

 advantage of the deep cover in which the^- 

 dwell. 



"(4) ^lost small mammals, especially 

 those of the forest and the thickets and the 

 tall grass, have a coloration which can 

 hardly be called especially revealing or 

 especially concealing; they rely on the 

 cover and on their habits, and not upon their 

 coloration, for concealment. The utmost 

 that can, with any show of reason, be 

 claimed as regards these is, that the law of 

 natural selection, or whatever law it is 

 that is responsible for their coloring, has 

 set wide coloration limits, which the 

 species cannot transgress, but within 

 these wide limits has allowed each species 

 to develop any kind of coloration pattern. 

 It is, of course, very difficult to define the 

 exact boundary lines separating the large 

 classes of animals with a very slightly con- 

 cealing or ver}' slighth' revealing color- 

 ation from the still larger class where the 

 coloration can scarcely be called either 

 re\"ealing or concealing. ]\Ian>- birds, such 

 as many of the Sparrows which live in the 

 grass, are inconspicuous, and may be said 

 to ha\'e a concealing coloration; and yet 

 their close kinsfolk, with a somewhat 

 similar coloration, may live under con- 

 ditions which make their coloration really 

 possess little of either revealing or con- 

 cealing quality. 



"(5) As regards the majority of birds 

 and mammals the prime factors in securing 

 their safety are habit (including bodily 

 capacity) if they do not trust to conceal- 

 ment, and habit and cover if they do trust 

 to concealment. Among these birds and 

 mammals the coloration is always a minor, 

 and often a negligible, factor, and the coun- 

 tershading has no effect whatever, one 

 wa\' or the other. 



"(6) A large majority, probably at 

 least three-fourths, or over, of the birds of 

 temperate North .America, have coloration 



