LIMITED TRAPNESTING 



6. Probable clutch size: winter, spring, summer, and fall. 



7. Probable winter pause duration. 



8. Probable annual persistency. 



9. Probable length of biological year. 



LIMITED TRAPNESTING FOR 

 ESTIMATING THE PROBABLE ANNUAL EGG RECORD 



In this section the five short-time measures of production are considered for 

 their accuracy solely from the standpoint of annual egg production. The correla- 

 tion coefficients, the calculated and actual egg records, and the percentage ac- 

 curacy of the short-time measures are shown in Table 1. Table 2 compares the 

 actual production with the production calculated by the regression formulas. 



Table 1. — The Value of Limited Trapnesting for Estimating Probable 

 Annual Egg Record. 



C. Daily in October only 



(31 days) 



D. Daily in August only 



(31 days) 



E. Daily from first egg to 



January 1 



-|-.2209± .0170*** 195** 218 



-f.6302± .0102 221* 219 



187** 



4-.433S+ .0133 223* 216 



99 



85 



97 



*Calculated by the regression formula. 

 ** Calculated from the limited records by the following factors: 15.2 for the 24-day record 

 (24 '365 of a year); 4.34 for the 84-day record; and 11.77 for the two 31-day records. 



*** Regression was found to be non-linear. The association is therefore measured by the corre- 

 lation ratio which was .3003. 



Trapnesting the first two days of each month is a convenient method of limited 

 trapnesting which has been frequently used for estimating annual egg weight. 

 The two-day observations began October 1 and ended September 2, making 24 

 days of trapnesting in the year. Table 1 shows an accuracy of 95 or 96 percent 

 for this method, depending on how the annual production is calculated. 



Breeders desire to know what birds to discard and what birds to retain when 

 the chief interest is high annual records. The regression table supplies this in- 

 formation. Table 2 A shows a remarkable agreement between calculated and 

 actual record. For example, if a breeder selected hens that laid 14 eggs on the 

 24 days trapnested, they would be e.xpected to lay about 215 eggs in a year. 

 If he was looking for 250-egg hens, the 24-day record should show about 18 eggs. 



Trapnesting the first week of each month was but slightly more satisfactory than 

 trapnesting for the first two days of each month for estimating the probable an- 

 nual records (Tables 1 and 2 B). 



