16 



MASS. EXPERIMENT STATION BULLETIN 438 



clutch size. Trapnesting from the first egg to January 1 gives only an approxima- 

 tion of probable subsequent spring clutch size, while the trapnest record in Octo- 

 ber at the beginning of the year has no value for predicting spring intensity. 



Table 12. — The Value of Limited Trapnesting for Estimating Spring 



Clutch Size. 



Summer Clutch Size 



Egg production during June, July, and August has an important bearing on 

 the annual record, according to the work of a number of investigators. Summer 

 intensity may be measured in a number of ways, and mean clutch size is reason- 

 ably satisfactory. Summer intensity should be given due consideration by the 

 breeder and the value of limited trapnesting for this purpose requires attention. 



Results obtained by the five methods employed are presented in Tables 14 

 and 15. However, the regression of summer clutch size on October egg produc- 

 tion, and on egg production to January 1 was not calculated because of the lack 

 of correlation found. 



Table 14. — The Value of Limited Trapnesting for Estimating 

 Summer Clutch Size. 



