202 TECHNICAL BULLETIN 9 



Discussion and Summary. 



Annual persistency is a characteristic bearing a vital relationship to fecund- 

 ity. Its duration is affected by environmental influences and by inherited 

 traits concerned in fecundity. No conclusive evidence is presented in this 

 report to indicate that high persistency behaves as a simple recessive in in- 

 heritance as has been suggested by Hurst (loc. cit.). In this climate persist- 

 ency may be increased to some extent by hatching before April 15, with such 

 birds as are studied here. Early sexual maturity, non-broodiness and high 

 winter rate probably show some linkage with high persistency. At any rate, 

 tliere is no evidence of antagonism in attempting to combine these desirable 

 traits in the same individual. Valuable information for selection purposes 

 has been disclosed by these studies. Partial correlation coefficients will be 

 used in a later publication to remove some complications. 



The general relation of persistency to winter and annual production for 

 the whole population studied is shown in the following table: 



Character of Birds Winter Production Annual Production 



Persistency above population mean 69.84 198.59 



Persistency below population mean 51.57 145.67 



Persistency of 3l5 days or more 71.13 201.98 



(Mean 347 days) 



Persistency below 315 days 52.83 150.75 



(Mean 249 days) 



Mean Persistency by Years 



rds Average Persistency 



247.53 

 280.74 

 285.49 

 325.29 

 301.00 

 329.67 

 316.33 

 320.47 

 300.19 



The cliicf findings of this report may be summed up as follows: 



1. Early hatching is moderately correlated with high annual persistency. 



2. Age at first egg is very intimately negatively correlated with high per- 

 sistency. 



3. Weight at first egg shows significant negative correlation to persistency. 



4. Winter rate of laying is moderately correlated witli persistency. The 

 two traits appear to be partially complementary. 



5. Length of winter pause is but slightly positively correlated with per- 

 sistency. 



6. Total days broody is not significantly correlated with persistency. 



7. The presence of broodiness sliows a fair negative correlation to liigh 

 persistency. 



