No. 615] 



EGG PRODUCTION 



217 



Moult.— Moulting exercises some influence on the num- 

 ber of eggs produced, since birds that are moulting often 

 do not lay, particularly during the fall moult. Moulting 

 itself may be induced at certain seasons of the year by 

 changes in management, especially those changes that 

 tend to stop egg production. Such changes apparently 

 change the course of the metabolism of the bird. Brood- 

 iness in late summer and early fall appears to be a com- 

 mon cause of the onset of a moult and consequent cessa- 



tion of egg production. At least one might draw this 

 conclusion from the fact that egg production, as the usual 

 rule, ceases with a broody period, for in most instances 

 the last egg laid in late summer or early fall coincides 

 with the beginning of a broody period. It is not clear, 

 however, whether the moult starts because the bird has 

 reached the limit of her production period, or whether 

 the moult begins because of the interruption to egg pro- 

 duction due to the onset of the broody period. 



In the Ehode Island Eeds we have observed a partial 

 moult that begins in the early part of the summer and as 

 a rule seems to affect egg production very little. In the 

 autumn this partial moult is followed by a more extensive 

 (often complete) moult attended by cessation of produc- 

 tion. It is possible that the summer moult has been in- 



