FEATHER PIGMENTATION AND INTENSITY 6 



probably intensified by inbreeding. There is still considerable overlapping in 

 the two lines in the medium color-group, and the tendency for males to show 

 lighter plumage color than their sisters still persists. 



Table 3. — Mean Hatchability and Annual Production of Three 

 Generations. 



Mean Hatchability, Per Cent Annual Egg Production 



Light Line Dark Line Light Line Dark Line 



1928 58.5 69.8 229 218 



1929 78.7 73.0 197 206 



1930 83.0 50.0 197 180 



The foimdation group of light-colored birds includes 29 individuals with 

 complete annual egg records. The mean for this group is 188 eggs, while the 

 foundation dark-colored group including 33 birds averaged 184 eggs. This 

 difference of four eggs is not statistically significant. 



Hatchability of breeding females varied widely and not consistently in the 

 three seasons reported. 



Annual egg production showed a significant decrease on successive generations 

 as might be anticipated as a concomitant of inbreeding. 



PLUMAGE COLOR AND WINTER INTENSITY 



The foundation females in the light and dark lines may be rougUy classed 

 into five groups with respect to surface plumage color of back. The accompany- 

 ing table gives the number of individual birds in each group and the mean winter 

 clutch size of the group. It will be observed that the light and dark lines overlap 

 in the medium group and that the mean clutch size in this group in the two lines 

 is essentially the same. A consistent decrease in winter clutch size with increased 

 color is observable in all classes with a significant number of birds. The fact 

 should be mentioned in this connection that the two individuals with the ex- 

 tremely large clutch size of 10.5 and 10.6 respectively, are in the very light 

 group. One individual of the dark line in the medium group showed a clutch 

 size of 9.3. 



Foundation Females — 1927 



Table 4. — Surface Plumage Color of Back and Winter Clutch Size. 



Color 



Very light. 



Light 



Medium... 



Dark 



Standard... 

 Total.. 



1928 Generation 



Complete records on plumage color of the progeny hatched in 1928 are not 

 available for study. Consequently, the relation of plumage color and clutch size 

 cannot be considered. 



