WIXTKH CYCLE AND WlNl'I'.K 



Number of birds 



Mean lengtb of winter pause 



Winter pause standard deviation 



Mean winter prodiiotion 



Winter production standard deviation 



CoelRcient of correlation 



Regression of winter pause on production 



Regression of production on winter pause 



Mean winter productioi\ is lower in tiic above group of pause birds tban 

 for tbe total population given in section 23 because non-pause birds tend to 

 have higher winter records than do pause birds. About the same degree of 

 variation in winter records occurs in l)oth ca.ses. 



A rather significant negative correlation coeflicient shows tluit in general 

 an increase in length of pause is associated with a decrease in number of 

 winter eggs. A coefiicient of much greater magnitude would appear if the 

 time element were the only consideration. There is the possibility that pause 

 birds tend to possess desirable fecundity traits that are lacking in non- 

 pause birds. 



25. Correlation llelween W^intcr Production Belou' the Mean and Presence 

 of Winter Pause for Total Population. 



Coefficient of correlation 



-f .4.255 ± .0095 



The above table illustrates a rather pronounced correlation between low 

 winter egg production and the presence of winter pause. Winter pause lias, 

 therefore, proven to be a trait inimical to high winter egg record throughout 

 the nine-year period of tlie experiment here re])orled. 



26". Correlation Between Leni/th of Winter Pause and Annn(d Production. 



There are available for study 1348 pause birds with annual egg records. 

 Tabulations have been made to discover how the length of winter pause 

 affects annual egg production. Following are the constants: 



