WEIGHT 



91 



stricted feeding opportunity, attendant upon limited movement during periods of incubation 

 and brooding, may serve to further reduce weight in grouse. Sex, too, introduces an im- 

 portant differentiation. 



Interpretation of the effect of each of these influences is dependent upon the availability of 

 records extensive enough to enable analysis on a seasonal and yearly basis for each region 

 to be studied. Attention must also be given to a number of small but important items which 

 are often overlooked, such as the interval elapsing between collecting and weighing the bird, 

 and the conditions under which it has been kept during this period. It is even pertinent 

 to point out that the accuracy of the scales used should be checked. In table 10, normal 

 variations in the weight of New York grouse, birds heavily parasitized or evidently diseas- 

 ed have been excluded, as have those which died from other causes of an abnormal nature. 



TABLE 10. 



AVERAGE MONTHLY WEIGHTS OF 391 ADII[>T AND 108 YOUNG GROUSE 

 COLLECTED IN NEW YORK ST VTE— 1931-1911 



Seasonal Trend 



An analysis of weight trends and differentiations as here illustrated (figure 10) raises many 

 an interesting question of influence and relationship. In distinct contrast with the Scotch 

 grouse of Great Britain, ruffed grouse of all ages and sexes in general seem to follow much 

 the same trend at approximately the same time. They reach their highest weight of the year 

 in November or December following a period of fall plenty. The average weight of New 

 York grouse at this season is about 1 lb. 7 oz. (651 grams) for adult males and 1 lb. 5 oz. 

 (587 grams) for adult females. With the onset of real winter, certainly by the middle of 

 January in New York, a loss in weight sets in, gradual at first but more rapid as the winter 

 progresses. This culminates about the middle of March with an average loss of from 1^,4 to 

 21/^ oz. (35 to 69 grams). 



