770 



PHYSIOLOGICAL STVDIF.S OF THE RIFFKD GROUSE 



not sufficient to maintain l)odv weight, although \vh\ thev did not eat more is not clear. 



It is to he noted from previous experiments that increased muscular activity greatly raises 

 the metabolic rate. In confinement, however, muscular activit> is markedly reduced as com- 

 pared with birds whose movements are not greath restricted. Within a certain range of air 

 temperature the metabolism of gallinaceous birds is unaffected by air temiierature itself, tmt 

 either below or above this range it is accelerated to maximum levels. 



Of the grouse living at 85°F. two (Croup C) gained weight, while five fGroup D) lost. 

 Because less body heat is required as the environmental temperature rises, physiological 

 demands should be satisfied by lower food consumption (caloric values being equal) under 

 such conditions. Yet it is apparent that the caloric intake of the birds in Grouj) D was inade- 

 quate for vital needs. On the other hand. Group C birds consumed relativeK larger amounts 

 of food than was necessary physiologically at an air temperature of o5°F. These two birds 

 were able to gain even more. |)roporlionally. than Group A, although consiiniing no more 

 than (iroup B which could not maintain weight at 65°F. 



I.SOi 



Weight Loss 

 Water Consumption 



■ 1.50 



125 



1.00 



Q75 



050 



025 



FEMALE MALE 



LIVING AT 40° F. 



FEMALE MALE 



LIVING AT 65 °F 



FIGURK '>\. HKI.^TIONSIIIl' HKTVVKKN BODY WKK.IIT LOSS \\l) WATER CONSUMPTION OK M)l l.T 

 GROUSE DURING PROLONGKn KASTIN(. \T TWO MR TKMPF.RATIRKS 



A possible explanation for \ariations in weight and food consumption is that a tempera- 

 ture of 8.S°F. is physiologically unfavorable during winter months for confined grouse in full 

 |)Iumage and while in a condition oi active digestion. Under these conditions two of the birds 

 manifested polypnea (an exaggerated rate of breathing or panting) which is a chief physical 

 means for cooling the boiK 1>\ tlic vaporization of water from \hr lungs and air sacs. 



Another phase of the experiment was desigru'd to study the effect of the ingestion of food 

 upon grouse in a physiological state of undernutrition. Ten birds which had survived the 



