54 



YOSEMITE NATURE NOTES 



HOW TO TELL A BEAR FROM A BEAVER 



Mammals comprise those creatures 

 with hair on their bodies and which 

 suckle their young. These form but a 

 small part of the animal kingdom; hence 

 it would be inaccurate to restrict the 

 term "wild animal" just to mammals, de- 

 spite popular use to the contrary. After 

 all, worms are wild animals; so are frogs; 

 so are birds; so are millions of kinds of 

 insects, just to name a few others! 



For convenience in identification, sci- 

 entists have divided mammals into sev- 

 eral "orders" or large groups. Six of these 

 are represented in the Yosemite list: 

 Insect-eaters (Insectivora) ; bats (Chirop- 

 tcra) ; flesh eaters (Carnirora) ; rodents 

 (Rodentia) ; rabbits and their allies 

 (Lagomorpha) ; and even-toed, hoofed 

 mammals (Artiodactyla) . 



aaolc lin<K 3l£| = W 



YrtNH*6i2 



Dental characteristics play a large 

 part in this classification, and, in a gen- 

 eral way, indicate the food habits of each 

 group. This fact may assist in keeping 

 the differences between orders in mind. 

 We will, therefore, pursue the subject 

 further, utilizing drawings of the skulls 

 of typical Yosemite species made by 

 Richard G. Miller. :: " The symbols that 

 look like a row of fractions represent 

 the number of teeth on one side of the 

 face, reading from front to back, uppers 

 and lowers. 



The insect-eaters (moles and shrews) 

 have very sharp teeth which are especial- 

 ly suited for cutting through the hard 



I irvch 



Bi<j Broun Bat 



parts of insects and rapidly chopping up 

 food. This even applies to the jaw teeth, 

 which in most other orders serve as grind- 

 ers rather than shears. The front teeth 

 are long and sharp, useful for grasping 

 and holding lively prey. 



The scientific name for bats, Chirop- 

 tera, refers to the structure of the wing 

 (Greek cheh, hand, plus pterone, wing), 

 rather than to food habits (see p. 59). 

 However, the teeth of Yosemite bats are 

 specialized for catching and eating in- 

 sects, so we may also think of them as 

 "flying insectivores" rather than "flying 

 mice" as is popularly supposed (see be- 

 low, "Rodents") . 



The canine or "eye" teeth of Yosemite 

 bats are quite large and well suited for 

 seizing and grasping. The jaw teeth are 

 quite jagged and offset between uppers 

 and lowers to provide a definite shearing 

 action. This enables them rapidly to chop 

 up and devour the many insects that are 

 captured in flight. 



6 inches 

 Black Bear § j £ f ■ HZ 



YA\NH*359 



* See "Food Habits of Yosemite Mammals as Indicated by Their Teeth," Yosemite Nature Notes, 

 24 (2-5), February, March, April and May, 1945. 



