Autumn Moults of Adult and Juvenile Lesser Redpolls in Nottinghamshire, England

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Abstract
Molt was studied in a population of lesser redpolls C. f. cabaret breeding in Nottinghamshire, England during 1977-1979. A modified linear regression technique for date on molt score was developed to estimate adult molt commencement dates and rates of progress. About 85% of each sex normally commenced molt within separate 3 wk periods, females starting 6 days later than males on average. Mean population molt durations (53-60 days in this study) were shown to be at least partially dependent on commencement dates, so that there were considerable annual variations; late breeding seasons resulted in shorter molting periods. Latitudinal differences in molt parameters could not be confirmed because of annual variations and incomplete sampling through the molt period. Some breeding birds which had commenced molting were able to reduce energy requirements, either by slowing feather growth or by suspending their molt temporarily. Juveniles from early broods commenced their autumn molt in the 2nd half of July and completed by early Sept., moving away from the molting areas before the adults. In 1978, many juveniles from later broods had not even commenced molt by mid-Sept. Juvenile autumn molt duration was about 6-7 wk.

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