^xp!*Sta. } LIFE HISTORY OF THE KANGAEOO RAT. 35 



probably soon reoccupied even if the original owner is captured, 

 and in the course of a few months the reworking of the abode oblit- 

 erates the signs of destruction. 



Droppings of the kit fox show an abundance of bones of small 

 mammals of kangaroo rat size, among them those of spectahilis. 



Bobcats {Lynx haileyi) and coyotes {Canis mearnsi) probably 

 are a prejudicial factor. Skunks may sometimes be able to surprise 

 the kangaroo rats, but probably not often. The western horned owl 

 (Bubo virginianus pallescens) ^ the barn owl (Tyto alba 'pratincola) , 

 and perhaps others may well be among the most feared enemies, but 

 no special investigation of owl pellets on the reserve has been possible. 

 In 592 barn-owl pellets from California were found remains of 230 

 kangaroo rats, only one other rodent being represented by a larger 

 number (McAtee, 1921, 258). 



Much more information on enemies is needed. The relativel}^ low 

 rate of reproduction (see p. 18) indicates comparative freedom from 

 inimical factors. 



PARASITES. 



Dipodomys s. spectahilis is regularly infested with a species of flea, 

 Ctenophthalmus sp. Seldom or never is a specimen taken m reason- 

 ably fresh condition without some of these parasites present on its 

 body, though of course they desert the body of the host after it be- 

 comes cold, and hence dead specimens left too long may be free from 

 them. The den conditions are ideal for the breeding of this para- 

 site, because of the great quantities of fine, dusty, organic refuse 

 littering the tunnels and furnishing food and refuge for the larvse. 

 As demonstrated to us by F. C. Bishopp, of the Bureau of Entomol- 

 ogy, a handful of this refuse taken from the floor of a burrow within 

 arm's length of the entrance is almost certain to contain these larvse. 



Less regularly present, perhaps because of its different life his- 

 tory, is a small tick, TromMcula sp. At times this parasite is very 

 common, being present on nearly every individual rat, and at other 

 times specimens are difficult to find ; it appears to be more commonly 

 present in summer and fall than at other seasons, and is found at- 

 tached chiefly to the ears. 



No internal parasites have been detected. The nocturnal and fos- 

 sorial habits of the animal seem to give complete protection against a 

 form of parasite which is very common among some other rodents of 

 the Range Eeserve, notably Lepus and Sylvilngus. Nearly all rab- 

 bits are infested with " warbles." the larvse of a species of bot-fly, 

 Cuterehra (family Oestridae). Other small mammals also are occa- 

 sionally parasitized by the Cuterehra^ but in the handling and exami- 

 nation of perhaps 200 or more individuals of spectahilis and merfia/ini^ 

 we have yet to find a single case of infestation by an oestrid fly. 



