WINTER CYCLE AND WINTER PAUSE 



185 



Number of l)irds ..... 



Mean length of winter pause 



Winter pause standard deviation 



Mean winter production 



Winter production standard deviation 



CoetRcicnt of correlation 



Regression of winter pause on production 



Regression of production on winter pause 



2134 



32 26 

 ±21.92 



56.87 

 ±23.51 



—.2873 

 -.268 



—.308 



.0134 



Mean winter production is lower in the above group of pause birds than 

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

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

 variation in winter records occurs in both cases. 



A rather significant negative correhition coeHicient sliows that in general 

 an increase in length of pause is associated witii a decrease in numljer of 

 winter eggs. A coefficient of nuich greater magnitude would appear if the 

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

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

 pause birds. 



25. Correlalion lielween ]l'"iuter Production Beloxv the Mean and Presence 

 of Winter Pause for Total Population. 



Coefficient of correlation 



-(-.42.55 ± .0095 



The above table illustrates a rather pronounced correlation between low- 

 winter egg production and the j)rcsence of winter ptiuse. _ M'inler pause has, 

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

 the nine-year period of the exj^eriment here reported. 



26. Correlation Between Lenyth of Winter Pause and Annual Production. 



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

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

 aiTects annual egg production. Following are the constants: 



