ADAPTATIONS TO DESERTS 



EAGAN; I was surprised at the rapid and dramatic drop in 

 body temperature in the species you mentioned. Was that the 

 antelope ground squirrel? 



HUDSON: When he was overheated? 



EAGAN; Yes. 



HUDSON: This is the antelope ground squirrel. 



EAGAN: And how many minutes was that, did you say? 



HUDSON: Three minutes. Of course this is a small animal. 



EAGAN: Is this accomplished just through transfer through 

 cooler air, or is it through conduction in the burrow walls? 



HUDSON: Well, he was transferred into an environment where 

 the temperature was all the same, so this is artificial, but the 

 substrate temperature was the same as the air temperature, so 

 conduction would be an important factor here. They show an inter- 

 esting behavioral response to this; when they become overheated 

 or become relatively warm and have the opportunity to spread out 

 on a cooler surface, they do this by extending their legs out, lying 

 very flat, and very close to the surface; this has also been reported 

 by people living in the desert where they can observe these animals 

 coming into the shaded areas or on to moist concrete. 



o 

 MORRISON: If you put the animal back at 42 C, how long does 



it take him to rewarm?In other words, if it took three minutes to 



cool, how long will the reverse process take? 



HUDSON: We have not done that. 



HART: Have you calculated the basal metabolic rate of the 

 Poor-will in absolute units at the thermo- neutral zone? 



HUDSON: In terms of calories? 



453 



