MASS. EXPERIMENT STATION BULLETIN 429 



Table 3. — Eggs Laid and Days of Laying During Annual Molt, 1938-1940. 



Complete Wing Molt 



Incomplete Wing Molt 



Neck (Cervical) 



Exhibition.. 23 25.0 51.0 



Production.... 71 31.8 59. C 



Breast (Pectoral) 



Exhibition 14* 8.9 19.2 



Production 34 11.9 25.6 



Thigh (Femoral) 



Exhibition 23 8.7 18.1 



Production.... 71 8.4 18.6 



Lower Leg (Tibial) 



Exhibition 23 3.3 8.4 



Production 70 3.7 10.1 



Back (Dorsal) 



Exhibition 23 19.5 40.0 



Production 71 22.9 42.8 



Wing Primaries 



Exhibition.... 23 14.7 32.5 



Production 71 30.6 72.6 



*Observations were not made on the breast region the first 



10 42.4 69.0 



60 33.3 63.0 



7 10.1 18.3 



36 17.5 36.5 



10 15.6 28.1 



60 11.8 26.0 



The production-bred group, however, averaged to lay twice as many eggs as the 

 exhibition birds during wing molt. The fact should be remembered that molting 

 all over the body is generally going on during this period and that many individ- 

 uals may stop laying entirely. 



In the population with incomplete wing molt, there was for the most part a 

 slightly longer period of egg laying and a greater number of eggs laid than in the 

 group with complete wing molt. This fact indicates that birds that are very late 

 in completing their wing molt are likely to molt in other feather tracts over a 

 somewhat longer period and are more likely to lay a greater number of eggs during 

 molting. 



Persistency in Relation to Wing Molt. — Persistency may be measured by the 

 length of the biological laying year, which usually ends during the annual molt. 

 Since the molting of wing primaries is more consistant than that of the other 

 feather areas studied, it furnishes a rather satisfactory measure of molting be- 

 havior. Since persistency is the most important inherited character thus far 

 studied in relation to annual egg production (Hays, 1944), it is obvious that the 

 relation of molting behavior to persistency is very important. In table 4 are 

 recorded the mean length of the biological year in days, the mean number of eggs 

 laid, the mean number of wing primaries shed when laying stopped, the average 

 date of completing wing molt, and the average date when the biological laying 

 year ended. 



