62 THE SPECIES— ITS TAXONOMY, RANGE, BIOLOGY, & ECONOMIC IMPORTANCE 



It was found that the average body temperature of the birds used was just over 107°F. and 

 that it varied slightly with the air temperature and with activity. The data also demonstrated 

 a regular fluctuation each 24 hours, in which the temperature of the birds was highest between 

 2:30 p. m. and 5:30 p. m. and lowest between 11:30 p. m. and 2:30 a. m. Wetting the 

 birds with a water spray in simulation of rainfall caused their body temperature to decrease 

 sharply. The colder the water as well as the surrounding air, the greater the degree of drop 

 and the slower the rate of recovery. The effect was also much more severe on three speci- 

 mens afflicted with an intestinal disorder. 



The average rate of breathing among inactive grouse was nearly 63 respirations per 

 minute. This rate increased with the activity of the bird, as well as with the body tempera- 

 ture. It appears, however, to be a less significant indication of relative vitality than either 

 body temperature or heart rate. 



The average heart rate of inactive grouse was found to be about 342 beats per minute. Like 

 respiration rate it varied with the bird's temperature, but there was a tendency for it to 

 become more rapid as the en\ir<)nnient became colder. When the birds became excited a 

 pronounced and almost instantaneous increase occurred. 



To study the effect of starvation on the bird, 12 grouse were held for nine days with- 

 out food. While this did not markedly affect the general level of body temperature until the 

 last day, it did cause a drop in the low point of the 24-hour cycle each night. Since these 

 birds were held at a constant air temperature this drop would be greater under natural condi- 

 tions where the air becomes colder at this time of night. Thus birds without adequate food 

 would have greater difficulty than well-fed ones in preventing excessive reduction of body 

 heat. Furthermore, the fact that these birds did maintain their body temperature, especialh 

 when living at low air temperatures, demonstrates that such conditions force birds to draw 

 on their reserve in order to compensate. 



In addition to the above, six grouse were allowed neither food nor water. After the 48th 

 hour under these conditions their temperature-regulating mechanism broke down and in sev- 

 eral cases death resulted. A definite daily need for water is thus apparent. 



WINTER CROU.se DROPPINGS (LEFT) RESULTING KKOM GOAKSE, IlK.llLV FIBROUS FOODS AND SPRING 

 DROPPINGS (right) PRODUCED AFTER THE BIRDS BEGIN TO FEED ON FRESH GREEN MATERIAL 



