180 



TECHNICAL BULLETIN 8 



hints at some linkage relation between the dominant genes for iiigh winter 

 intensity and the recessive gene for non-pause. 



16. Correlation Between Winter Rate Below the Mean and the Presence of 

 Winter Povse for the Total Population. 



Coefficient of correlation 



4-.3734 ± .0100 



Winter rate as used in all the calculations is the net rate of laying with 

 all pauses of four or nioie days deducted. Tlie above table siiows tiie rela- 

 tion of net rate of laying to the presence of winter jiause. This table dis- 

 plays a moderately intimate relation between low net rate and tlie presence 

 of winter pause. 



n. Correlation Between Size of Winter Clutch and Len(/th of Winter Pause. 



Size of clutch represents the number of eggs laid on successive days. In 

 very extreme cases a pullet may lay as many as iifty eggs in succession pre- 

 vious to March first and the same bird may exhibit a few clutches of one. 

 In order to arrive at a constant lo represent the clutch size of an individual 

 bird, it has been necessary to calculate mean clutch size during the winter. 

 Such calculations have been ncxde on ail pause birds. The range in mean 

 clutch size of individuals was found to be from 1 lo 11.9. The class interval 

 used was 1. Only one bird was omitted from this study because its class 

 range fell between 1-5 and 15.9. CluLcii size is really a measure of intensity 

 of laying. Its relation to winter pause duration is of marked significance in 

 breedinii' for fecimditv. 



Constants obtained in Lhis correlation stiulv are as follows: 



Number of birds .... 



Mean winter clutch size 



Winter clutch standard deviation 



Mean length of winter pause 



Winter pause standard deviation 



Coefficient of correlation 



Regression of v/inter clutch on winter pause 



Regression of winter pause on winter clutch 



2133 

 2.41 

 ±1.11 

 32.27 

 ±21.92 

 —.0674 

 —.003 

 —1.32.5 



.0145 



On the average, winter clutch size closely api)roaches 2.5 but the magni- 

 tude of its standard deviation indicates considerable variability in clutch size. 

 A small negative correlation was discovered between clutch size and winter 

 pause duration. While this correlation is significant as judged by its prob- 



