LIMITED TRAPNESTING 



21 



LIMITED TRAPNESTING FOR ESTIMATING 

 DURATION OF WINTER PAUSE 



Probably the only tj^pe of limited trapnesting that will give information on 

 length of winter pause is continuous trapnesting from first egg to January 1. 

 In this report only birds with a pause of eight or more days between November 1 

 and March 1 are considered. There was a population of 714 which gave a correla- 

 tion between egg production and pause duration of — .2111 ± .0241. Regression 

 was non-linear and the correlation ratio was .2954. This is a rather significant 

 negative correlation which is somewhat spurious. 



The regression of pause duration on production to January 1 was calculated, 

 and predicted and actual pauses are recorded in Table 18. The estimates agree 

 rather well with the actual length of pause, except for the very low producing 

 birds. For practical purposes, trapnest records up to January 1 should be useful 

 in reducing the length of winter pauses. 



Table 18. — Limited Trapnesting as a Means of Estimat ng Dur.ation 

 OF Winter Pause. 



E. Regression^ of Pause Duration on Production to January 1. 



Winter 



Egg 

 Record 



Number 



o 1 



Birds 



Duration of Winter Pause 



Estimated 



714 



46.7 

 44.6 

 42.5 

 40.4 

 38.3 

 36.2 

 34.1 

 32.0 

 29.9 

 27.8 

 25.7 

 23.6 



62.5 

 56.7 

 47.2 

 39.4 

 36.2 

 33.1 

 35.4 

 30.3 

 34.9 

 27.8 

 28.2 

 29.2 



^ Regression was not linear. 



LIMITED TRAPNESTING FOR ESTIMATING PERSISTENCY 



Workers generally agree that high production near the end of the first laying 

 year is one of the most important characters of a heavy layer. Knox, JuU and 

 Quinn (1935) recommended August and September production as one of the 

 best measures of persistency. Lerner and Taylor (1937) found age at last egg 

 to be a reliable measure of persistency. 



