Sex-Specific Differences in Molt Strategy in Relation to Breeding in the Wandering Albatross

Abstract

The extent of molt of primary feathers was studied in relation to the status and to the duration of the interval between breeding attempts in the Wandering Albatross (Diomedea exulans). The replacement of primaries lasts for more than one season, birds showing a typical wave molt with one to three foci occurring on a wing. Molt never occurs on the breeding grounds. In breeding as in nonbreeding individuals, males invariably renew more feathers than females. Breeding males and females renewed each year an average of 8.3 and 7.3 primaries per wing, respectively. The extent of primary molt of breeders was directly related to the duration of the interbreeding period in females but not in males. Males and females breeding for the first time had fewer new feathers than did experienced birds. When they visited the nesting colonies, immature birds had fewer new feathers than did breeding birds of the same sex. In immature birds, the extent of molt was related to the body condition (mass) of males but not of females. The extent of molt was inversely related to mass gain from one season to the next in nonbreeding males. These results suggest that molting in the Wandering Albatross is probably an important constraint that could compete with breeding, particularly in females. Possible reasons for sex-specific differences in molt extent are discussed.