Moult intensity and chronology of Tundra Swans during spring and fall migration at Long Point

• Main Authors: G. Eoin Craigie, Scott A. Petrie
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Cygnus columbianus; Tundra
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.561.6537; http://www.bsc-eoc.org/download/lpwwrf tundra swan moult paper.pdf

were scored according to the proportion of growing feathers. Adult, subadult, and juvenile Tundra Swans moulted con-tour feathers at low intensities during spring and fall. Males and females of all three age classes had similar patterns and intensities of moult during spring and fall. Shared costs of incubation and brood rearing, perennial monogamy, and lack of a breeding plumage could be some of the pressures selecting for intersexual similarities in feather replacement during migration. Adult, subadult, and juvenile Tundra Swans moulted more intensively during fall than spring. Larger lipid reserves and seasonal dietary differences may allow fall-staging Tundra Swans to moult more intensively than spring-staging birds at Long Point. Overlap of nutritionally costly events (moult and migration) may be necessary as Tundra Swans spend half of their annual cycle on spring and fall staging areas. However, reduced daily nutritional costs associated with moulting at low intensities and migrating slowly apparently permits the overlap of these two life-cycle events. Résumé: Nous avons étudié l’intensité de la mue et la chronologie des regroupements de la population orientale (EP) du cygne siffleur (Cygnus columbianus columbianus) aux printemps 1999 et 2000 (n = 35) et aux automnes 1999, 2000 et 2001 (n = 47) à Long Point, lac Érié, Ontario. Pour vérifier les différences d’intensité de la mue selon l’âge, le sexe et la saison, nous avons attribué des points à 20 régions du plumage selon la proportion de plumes en crois-sance. Les cygnes siffleurs adultes, subadultes et jeunes subissent une mue de faible intensité de leur plumage de