Factors Affecting the Duration of the First Annual Rest

THE period of non-production following the first laying year is frequently referred to as the annual molt. Although the close association of cessation of egg production with the process of shedding and replacement of feathers has been adequately demonstrated (Marble, 1930), certain differences in this respect exist between birds with different production characteristics. Marble has found that in cases of higher producing individuals molting begins before production has actually stopped, while in lower producing individuals little if any molt occurs before complete cessation of laying. Thus there is no complete coincidence of molting with the period of non-production between the first and second laying years. Since no molt observations were made on the birds considered in this paper, the period of nonproduction studied is termed here the annual rest. The methods followed in the determination of the duration of this period will be described later. The factors affecting the duration . . .