Common Chipmunk 347 



Besides the loud ^^chuck-chuck'' song It has several other 

 notes, one in particular being a trilled whistle of several differ- 

 ent notes that it utters when alarmed. This usually accom- 

 panies the final rush that it makes into a place of safety; pos- 

 sibly it is uttered in defiance of its pursuer, or it may be like 

 the nervous squeal of a child just escaping being caught in a 

 game. 



There Is much mystery about the mating of the Chip- mating 

 munks. Unquestionably they have a season of excitement 

 during the autumn. Rhoads thinks^ that this may be the 

 mating season, as the Tree and Flying-squirrels are known to 

 mate in late autumn or early winter, according to latitude. I 

 certainly saw the small Chipmunk of the High Sierra rutting 

 in late September. Then, again, the Chipmunk of the Northern 

 States will come out, like the proverbial Woodchuck, in Febru- 

 ary and race about Hke mad. This E. W. Nelson thinks' must 

 be their rut. But these same proofs are found In a greater de- 

 gree during the excitement of the early spring, with the addi- 

 tional evidence of the sexual organs being in a high state of 

 functional activity. The visiting Chipmunks described by 

 Burroughs may have been seeking mates. As late as May 5 a 

 male Chipmunk caught for examination (Cos Cob, 1906) 

 showed by the condition of the organs that this was its season 

 of procreation. 



On May 6 I found at the same place a female dead in a rat 

 trap, apparently a week or ten days after the birth of her brood. 

 Another female caught that day for examination was obviously 

 at the point of becoming a mother. 



As early as May 21, at Cos Cob, Conn., the young, already 

 half grown, have been seen, and on September 27, 1906, I saw 

 two, about half grown, follow an old one for some fifty feet from 

 the den. On October 8 I captured for examination a female 

 that was, or recently had been, suckling young. On October 

 14 I saw a half-grown Chipmunk playing about the door of 

 Its parental home. 



' Mam. Penn., N. J., 1903, p. 62. ^ Ibid. 



