MICROBIOLOGY OF HIBERNATION IN GROUND SQUIRRELS 



they are like a bear; that is, they are easily aroused. Their 

 body temperature can actually be lower than the ambient tem- 

 perature. This is supposed to be due to the evaporative cooling 

 effect, but they will enter what is called a state of hibernation 

 at around 19° C, and as you lower the temperature, within reaLson 

 now, they get in an increasingly deeper state of hibernation. We 

 were trying to get pretty deep hibernation. 



TRAPANI: How low is the ambient temperature of the burrow 

 in the natural habitat of the animal? 



SCHMIDT: This has been studied by Dr. Mayer^ here in 

 Alaska. He has rigged up a very clever harness for the ani- 

 mal made out of guaze, on which he attaches a thermocouple. 

 The animal goes down into the burrow and drags the thermo- 

 couple with him. He has made recordings throughout the winter. 

 It will actuallv get below 0° C for certain periods of time. I 

 am sure there is a microclimate involved, too, but the tempera- 

 ture is quite steady in the burrow. 



TRAPANI: Then they will waken, shiver, and then go back 

 to sleep? 



SCHMIDT: The feeling is that they do arouse even in the natural 

 state, periodically, in their burrows, and they will fool around 

 a little while and then go back into hibernation. 



ANDREWES: Two questions I'd like to ask. Am I correct in 

 supposing that what you told us implies that these various phages 

 and other viruses that you put into the hibernating animal do 

 persist for very long periods of time in contrast with E. coll 

 which are not only relatively, but actually, disappearing? 



SCHMIDT: The E. coli get down to a rather low level. The 

 studies with bacteria were for longer periods of time; how- 

 ever, I think there is a difference. I don't know just where these 

 E. coli go, I can't account for this; there are a number of pe- 



2 Mayer, W. V. 1960. Bull. Museum Comp. Zool. Harvard Univ. 124: 131-154. 



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