Order LAGOMORPHA 189 



by more than three-fourths of the hunters and making up nearly 

 half of the total bag of game. The other two species are re- 

 stricted in range and are of little importance from a hunter's 

 standpoint. 



Economic Status. — In some years cottontail rabbits do con- 

 siderable damage in orchards and nurseries in Illinois by eating 

 the bark of young trees, fig. 37. Also, at times they are trouble- 

 some in truck and home gardens. 



Rabbits are the source of most cases of human tularemia in 

 the United States. In 1939, in a period of particularly heavy 

 outbreaks among rabbits, 485 human cases of this serious dis- 

 ease were reported in Illinois. In most years since then, the 

 number of human cases in this state has been less than 100 an- 

 nually. More than half of the cases in Illinois in the 1936-1949 

 period were from the southern third of the state (Yeatter & 

 Thompson (1952:357). The tick that is the chief vector of this 

 disease feeds on its rabbit host from about the end of winter 

 until after the return of freezing weather in autumn, when the 

 tick becomes immobile and drops off its host. In about a week 

 after the onset of freezing weather, most of the infected rabbits 

 will have died and any rabbits not then infected will be free of 

 the disease for about 2 months. Sickly or sluggish rabbits and 

 rabbits found dead should be avoided as possible sources of the 

 disease. 



The domestic rabbit, Oryctolagus cuniculus, has been included 

 in the key for the identification of skulls because occasionally a 

 skull of this animal may be found. Not only have individuals 

 of this species been known to escape from captivity, but efforts 

 have been made to establish the species as a game animal in 

 Illinois. The domestic species and native species do not cross. 



KEY TO SPECIES 

 Whole Animals 



1. Ear from notch more than 75 mm. (3 in.) long; hind foot 



more than 120 mm. (4$4 in.) long 



white-tailed jackrabbit, Lepus toivnsendii 



Ear from notch less than 75 mm. long; hind foot less than 

 120 mm. long 2 



2. Hind foot less than 90 mm. (3i_> in.) long; back of animal 



grayish brown . . eastern cottontail, Sylvilagus jloridanus 

 Hind foot more than 90 mm. long; back of animal reddish, 

 with much black swamp rabbit, Sylvilagus aquat'uus 



