males, old males, young females, and young males) has an aver- 

 age weight that is significantly different from that of each of the 

 others, but there is a broad overlap between classes. The difference 

 between the weights of birds of the year and birds more than one 

 year old indicates that the young have not attained full size in late 

 October. The low variability of both weights and lengths of pri- 

 maries in young birds strengthens the conclusion that most of the 

 young are hatched within a short period of time. 



Y 



mm. 



700 800 900 1000 1100 gm». 



' WEIGHT 



• FEMALES -f- MALES 



Fig. 13. Weight of adult greater prairie chicken (X axis) plotted 

 against the length of primary number eight (Y axis) and the 

 regression line of Y on X. 



Figure 13 illustrates the correlation between the lengths of pri- 

 maries and the weights of individuals in adult birds. This figure 

 was prepared from the same data from adult birds that were used 

 in the preparation of Tables 2 and 3 and Figures 11 and 12. 

 Adult males could be distinguished from adult females in most 

 instances if both the weights and lengths of primaries were known. 

 The impossibility of obtaining such data from hunters on a mass 

 basis makes the determination of sex impractical by this means. 



Food Habits of the Greater Prairie Chicken 



Studies of foods eaten by the greater prairie chicken show that 

 cultivated grains make up an important part of its diet. Judd 

 (1905) examined 71 stomachs from the Midwest and Canada, rep- 

 resenting each month except July, and reported the following foods: 

 insects 14.11 per cent, grain 31.06 per cent, flowers and shoots 



[43] 



