CHAPTER XVII 



BIRDS, CONTINUED. THE ' OBLITERATIVE ' POWER OF APPENDAGES. ONE 

 USE OF LONG, BANDED TAILS CONJOINED WITH STREAKED BODIES 



OINCE the simple, organic outlines of an animal's body tend to reveal it 

 ^ to the eyes of enemies, Nature has resorted to many devices in order to 

 conceal those outlines. Such are various kinds of bold, contrasting patterns, 

 one of whose main effects is to hide the curved, characteristic forms by letting 

 into them, as it were, bays and notches of the background, of arbitrary shape. 

 Appendages are exactly the converse of this. They break the normal con- 

 tours by extending them irregularly outward, so that, figuratively speaking, 

 the animal is pulled out of shape and 'bridged over' into its surroundings. 

 "Appendages" include long tails, abnormally extended wing feathers, scap- 

 ular and other tufts, occipital crests, " beards," etc., and also fleshy outgrowths 

 such as combs and wattles — in short, all superadded external developments, 

 whether of skin or feathers. Many of these devices must have a remarkable 

 concealing-power. Think for instance of the Mexican Quetzal, or Resplen- 

 dent Trogon (Pharomacrus mocinno), with its enormously long, green, droop- 

 ing tail. How potently delusive to a hawk, flying over a seated trogon, might 

 be this indefinite, smooth extension of its green back into the maze of leafage! 

 Other notable examples are the peacocks and pheasants. In the case of many 

 pheasants an additional peculiar principle comes into play. Their long tails 

 are marked with strong transverse bars, of two or more colors and shades, 

 like stripes of alternate light and shadow on dead leaves or earth, which tend 

 to merge the tails into their backgrounds when the birds are still, and thus 

 contribute largely toward their obliteration. (See Fig. 133, Chapter XXVII, 

 p. 238; Fig. 120, and Chapter XXII, p. 159.) But when such a bird glides for- 



95 



