FEB., 1912. MAMMALS OF ILLINOIS AND WISCONSIN CORY. 141 



The amount of damage done depends upon the abundance of the animals 

 and is often serious. If the field is small and isolated, the spermophiles 

 sometimes collect and destroy almost the whole crop." (/. c., p. 42.) 



Concerning the habits of this species in Illinois, Kennicott says: 

 "Before the production of the young in May or June the old male 

 leaves the female, and appears to lead a solitary and more or less 

 wandering life, digging a temporary burrow, or occupying a deserted 

 one for a few days, wherever he may take up his abode. These summer 

 burrows may often be found, and sometimes are of considerable extent; 

 several of those which were examined were more than 20 feet in length, 

 being simple galleries from six inches to a foot below the surface 

 deeper in sandy soil opening at both ends, with the nest placed in 

 a small side chamber; others were of much less extent, sometimes with 

 but one entrance, and sometimes without nests. The winter burrow, 

 in which the pair hibernate and the female brings forth her young, is 

 deeper and more complicated, having always two entrances, or more. 

 In this, in a side chamber of suitable size, excavated above the level 

 of the rest of the burrow, is a large spherical nest of soft grass, entered 

 by an opening on one side. This nest is sometimes of the size of a 

 half bushel, the interior being generally lined with softer material than 

 the outside. The young are produced at the end of May or early in 

 June. I have observed from five to nine brought forth at a birth and 

 I am informed of two instances in which ten were found in a nest; 

 but the number is variable, the usual number being six or seven. The 

 young at birth are naked, blind and remarkably embryonic. Dr. 

 Hoy, who observed them in confinement, says that they have no 

 hair on the body before they are twenty days old and that the eyes do 

 not open until the thirtieth day. They continue to require the nourish- 

 ment and care of the mother for a much longer period than most rodents. 

 During the summer they begin to dig shallow burrows and leave her 

 before winter, to shift for themselves." (I. c., pp. 76-77.) 



This species hibernates during the winter. At the approach of 

 cold weather it retires into its burrow and remains there in a torpid 

 state for several months, or until the return of mild weather in the 

 spring. In northern Illinois it generally goes into winter quarters 

 late in October and reappears again about the first of April. On 

 March 27, 1910, I saw two at Burnside near Chicago, and on March 

 28 and 29, 1911, several were seen running about in the same locality. 

 On both occasions the weather for several days had been unusually 

 warm for the season. 



Hibernation Hibernation is a term applied by zoologists to 

 express a peculiar condition of torpid sleep in certain animals, which 



