KATE 01' LAYlNc; AND KCit! I'RODICTION 187 



l;;is been slunvii to be rather significantly related to winter fecundity. 

 I'robably a more important consideration is the relation of clutch size to 

 annual production. The entire population with annual records has been 

 tabulated in a correlation table and the constants obtained follow: 



Xuniber of bird.s 2;j.'}2 

 Mean annual production 182. 80 



Anniial production standard deviation ±42.91 

 Mean size of winter clutch 2.7(t 



Winter clutch standard deviation ±1.29 



Coefficient of correlation +.3.544 ±.0117 



On the studies reported herein egg production over a period of 36.5 

 days from first egg is taken as the standard for measuring fecundity. The 

 coefficient of correlation is positive and certainly significant so that winter 

 clutch size may be employed as a valuable criterion in the selection of 

 prospective heavy annual egg producers. Since winter clutch size appears 

 to be an inherited trait, there is opportunity for increasing fecundity by 

 breeding for greater mean winter clutch size. 



C. NET WINTER RATE 



Net winter rate is an expression for the rate of laying throughout the 

 winter season after deducting time spent in winter pause. It represents 

 the rate of laying for an average time interval of about 120 days in the 

 population studied. Net winter rate is considered first in relation to date 

 of hatching. 



S. Correlutiiin Betic^en Hatcliiixi Utile <(n<l Net }\'inter Rale. 



The population for the ten-year period (1916-192.5) is considered, and 

 tlie following constants are derived: 



N'uini)er of birds 3863 



Mean hatching date (Apr. 18) 4.3-5 



Hatciiing date standard deviation ±2.28 



Mean winter rate 67.79 



Winter rate standard deviation ±8.86 



Coefficient of correlation -f.0'100 ±.0109 



.ludgeil l)y the magnitude of the coefficient of correlation, there is no 

 relation between hatching date and net winter rate of laying. This fully 

 agrees with the findings set forth in section 3 where hatching date and 

 winter clutch size are found to be independent, 

 f). Correlation Between Age at First Egg and Net Winter Rate. 



Age at first egg is an inherited characteristic which has been shown by 

 the writer as well as by many other workers to be intimately correlated 

 with winter and annual production. In this report an attempt is made to 

 discover the relation of intensity to fecundity as well as to other character- 

 istics concerned in fecundity. Age at first egg has therefore been tabulated 

 against winter rate to derive the constants below: 



