Molt of Female Lesser Scaup Immediately Following Breeding

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Abstract
The chronology, pattern, and intensity of the molt following breeding in female Lesser Scaup (Aythya affinis) were studied from July through October 1981-1982 and in July 1984 in southwestern Manitoba. Nonbreeding females or females that were unsuccessful breeders began molt in mid-July, but females with broods delayed molt until August. The molt-intensity index was greatest during the flightless and postflightless periods. Molt persisted at low levels through the fall migratory period. Molt scores were most variable in the preflightless period. Molting began on the head, neck, and side and progressed to the belly, upper back, and chest; the lower back was the last area to molt. Feather replacement was most rapid in the wing and capital regions. The capital region and tail were the last areas in which molt was completed in fall-migratory scaup. Molt in postbreeding females probably is influenced by the length, timing, and success of breeding efforts. Individual and geographic differences in breeding chronology, habitat conditions, and postbreeding movements may contribute to variations in molt within a population of migratory scaup.