WEIGHT 



93 



male at his lowest weight in August. 



It is at year's end that the weights of the two sexes most nearly match, for the birds are 

 then only about 2V4 oz. (64 gramsj apart. Curiously enough, the weight difference is greatest 

 early in June shortly after the strain of egg laying and subsequent incubation is passed. The 

 female loses rapidly during the nesting period, reaching the low point, about 4 oz. 1.115 

 grams) below that of her more carefree mate, shortly after the chicks are hatched. 



It is not always easy to ascribe reasons for the variations in the weight pattern of either 

 sex. The influence of good food and of freedom from reproductive activities offer likely ex- 

 planations for the rapid gain of weight in the fall. Through the winter, the female appar- 

 ently loses weight more rapidly than the male but, like the Scotch grouse, with the coming 

 of spring, some is regained. Losses during e^g laying (mainly mid-April to early May in 

 New York) are not large. But the subsequent confinement of incubation brings on a swift 

 and deep decline in female weights, possibly in response to restriction of her opportunity 

 to feed freel). Al the low point, ihc average female will weigh but 1 lb. 2 oz. (500 grams). 

 This is probably dangerously low, for then it is, in raising grouse in cai)tivity, thai they are 

 most likely to die from chronic diseases. 



Throughout late June and July, the male is mouUing and slowly losing weight. Yet the 

 female, though likewise renewing her feathers, gains steadily. Grouse are able to call rather 

 quickly on their chemical reserve once their metabolic reserve has been exhausted. It is prob- 

 able that the hen approaches this condition earlv in June, the result of having already lost 

 almost one-sixth of her December weight and that from this time on a slow recovery takes 

 place. 



This may conlrii)Ulc Id the aliilitv of the female to i)ul on weight even though moulting 

 and caring for her brood. During the latter half of September or early October, she gains 

 almost 2 oz. (about 50 grams! to put her once more in good flesh. 



The male neither varies so greatly in his weight throughout the year, nor are the changes 

 as rapid. His drumming and strutting, so prevalent in early spring, do not prevent him from 

 gaining slightly as winter wanes, though the increase is not as pronounced as with the female. 

 By early June, though liis breeding dis|ilay is now largely an activ ity of the past and he has 

 scarcely begun to moult, his weight, curiously enough, is still dropping. This continues 

 slowly throughout the period of feather replacement and well into August. In the fall, he 

 apparently requires some three months to put on the same amount of flesh that the female 

 acquires in one. 



