THE TAII^-THE FEET 



107 



With Woodpeckers, Creepers and Chimney Swift the tail is modified 

 for use as a prop. 



The tail is exceedingly variable in form and is the seat of many 

 interesting marks and colors which are displayed intentionally or when 



Fia. 17. Tip of tail of (a) Downy Woodpecker and of (6) Brown Creeper, to show the 

 pointed shape in tails of climbing birds of different families. (Natural size.) 



the bird is in motion. Turkeys, Sage Cocks, Woodcock, spread the 

 tail when strutting; with a host of birds white on the outer tail-feathers 

 is conspicuously shown in flight or when the tail is nervously 'jetted' 

 or twitched by the hopping bird (see Color). Some birds not closely 

 related wag the tail (e. g. Spotted Sandpiper, Water-Thrush, Palm 

 Warbler, Pipit), though why 

 they should so do does not 

 appear to be known. 



The Feet. Birds' feet serve 

 a greater variety of uses than 

 any of the four organs whose 

 uses we are considering. Pri- 

 marily they are of value as aids 

 to locomotion, and the stu- 

 dent should first note their 

 length in wading birds like 

 Flamingoes, Herons, and Stilts, 

 and the relation between length 

 of foot and length of neck. 

 Aside from its length, the foot is 

 variously modified by the de- 

 velopment of webs and lobes 

 and lengthening of the toes and 

 nails, for swimming, running, 

 hopping, climbing and perch- 

 ing. The growth in the fall of 

 horn-like marginal fringes on 

 the toes of the Ruffed Grouse 

 and of feathers on the toes of 

 Ptarmigan, presents an unusual 

 case of seasonal adaptation in FlQ< 18> Flaming0) sh owinTrelative length 

 structure. of legs and neck in a wading bird. 



