ARCTIC METABOLIC ECONOMY 



333 



WORLD 



RANGE OF 



CLIMATES 1 ADAPTATION 



-60 



40 



ARCTIC 



TEMPE RATE 



A R C T I C ALASKA 

 30 MAMMAL ALS 

 200 BIRDS 



-20 



20 - 



TROPIC 



i 

 MAN 



Figure 16. — Temperature ranges for which warm-blooded animals are physiologically 

 adapted compared with those of the world's climates. 



3° above the lower range of body temperatures at rest. It is my view 

 that the body temperature of arctic mammals and birds remains at 

 a miniumum value characteristic of the resting state except when 

 excitement or activity elevates it above this well regulated minimum 

 level. 



During winter nights at Anchorage when the air was — 10° C. to 

 — 20° C. I found the body temperatures of six species of Alaskan wild 



