PHYSIOLOGICAL STUDIES OF THE RUFFED GROUSE 



759 



Data recorded when the birds were excited showed no appreciable difference between the 

 sexes. The extreme variability of the heart rate under these conditions, however, might easily 

 mask the difference indicated in inactive and quiet birds. 



TABLE lot. HEART RATES OF ADULT GROUSE LIVING* .\T TWO AIR TEMPERATURES 

 WITH RESPECT TO DIFFERENT DEGREES OF ACTIVITY 



*Normal cage life. 



AComposed of 288 individual records, 



tKeats per minute. 



When the data for quiet and excited birds are compared a tremendous and almost instan- 

 taneous increase in heart beat under stress of excitement is evident. 



To determine the influence of food on the rate of the various physiological activities the 

 birds were subjected to fasting for 100 hours and then tested (table 105). 



TABLE 105. AVERAGE STANDARD QUIET HEART R.VIE OF INACTIVE ADULT 

 GROUSE 100 HOURS AFTER WITHDR.\WAL OF FOOD 



There was no significant difference between male and female heart rates after fasting 

 100 hours. At this stage of fasting the destruction of cellular tissue and fat deposits was 

 progressing rapidly, the bird probably having utilized most i>f it.* reserve supph of liver 

 and muscle glycogen. Practically all of a grouse's energy for maintenance of vital processes 

 is derived from the combustion of body fat after fasting only 36 to 48 hours. Thus the true 

 sex difference in heart rate is masked by the catabolic activities being carried on at an ac- 

 celerated rate in the body. It should also be noted that, in addition to being considerably 

 slower and showing less variability, the heart rate of fasting birds was lower at 40°F. than 

 at 65°F. It is apparent that cardiac action is affected by fasting in similar physiologic ways 



