ANIMAL BEHAVIOR — WALKER 295 



Other means of communication are employed besides the voice. 

 Many animals stamp the feet when danger threatens or when they 

 meet an unknown condition that might prove to be dangerous. Deer 

 {Gervus and Odocoileus) stamp their forefeet. The African brush- 

 tailed porcupine {Atherura) stamps its hind feet. Sometimes there 

 may be three or four strokes of the hind foot in quick succession, 

 indicating irritation, displeasure, or warning. Skunks stamp both 

 forefeet. Wood rats and kangaroo rats tap, tap, tap with their 

 hind feet. Eabbits give warning by stamping their hind feet, and 

 most people have witnessed a woman express her displeasure by tap^ 

 ping her toes. This foot-stamping is a telegraph warning that many 

 animals heed. 



In addition to the voices and the stamping of feet there is the 

 buzzing somid produced by the rattle on the tail of the rattlesnake 

 {Crotalus). Snakes that lack rattles vibrate their tails when excited. 

 If the tail is touching dry vegetation a rattling sound is produced. 

 Most porcupines vibrate their tails; some species have peculiarly modi- 

 fied hairs that make very effective rattles. 



The visual telegraph is used by such animals as the American 

 prong-horned antelope {Antilocapra) and the American elk or wapiti 

 {Cervus). This is accomplished by erecting the hairs on the rumps of 

 the animals. By raising these hairs from their normal flattened posi- 

 tion until they stand almost on end, the light-colored bases of the hairs 

 are made very conspicuous and readily seen by other members of the 

 herd, who interpret them as a warning or signal flag. Wliite-tailed 

 deer also signal with erect tails. Because of this habit they are often 

 called "flag-tails." 



The booming of prairie chickens, hooting of blue grouse, and vari- 

 ous nuptial calls of grouse and ptarmigan are all vocal sounds. The 

 drumming of ruffed grouse {Bonasa umbellus) with their wings is a 

 remarkably far-carrying sound made by the males during the mating 

 season. The sharp "whirr" of the wings of a quail {CoUnus and re- 

 lated genera) when taking flight is undoubtedly a warning to other 

 members of the flock. 



LOCOMOTION 



The means by which most animals get about are so well known 

 that detailed discussion of them here would not be justified, however 

 interesting they might be as a subject of special study. In addition 

 to the well-known modes of progression such as walking, running, 

 hopping, flying, swimming, and crawling, some animals have devel- 

 oped special modes to meet their special requirements. Brief mention 

 of some of these may be made here. 



