| Summary: | Molting birds are facing temporal and environmental constraints, especially in some Anatidae because they renew all their flight feathers simultaneously during the short Arctic summer. We examined how these constraints could influence the molt phenology of greater snow geese and we explored the role of hormones and environmental factors in controlling molt and feather quality. We used a 20+ year database to examine the effects of environmental conditions and reproduction on molt phenology and we measured thyroid (T3) and stress hormones and body condition of individuals for two years to examine their effects on molt and feather quality. Our results show phenotypic plasticity based on an adjustment of feather growth speed rather than on advancement of the molt initiation date during late years. A decline in feather growth rate at the end of molt could be explained by a drop in T3 at this time. We also show that high levels of stress hormones could reduce molt intensity and body condition. However, the bending stiffness of feathers, an index of their quality, was not affected by body condition or stress hormone level. The phenotypic plasticity of molt allows a complete renewal of flight feathers before the end of the short arctic summer, regardless of reproductive phenology and spring environmental conditions, while maintaining a high level of quality for feathers. Les oiseaux en mue font face à des contraintes temporelles et environnementales, surtout chez certains Anatidae parce qu’ils muent toutes leurs plumes de vol simultanément durant le court été arctique. Nous avons examiné comment ces contraintes influencent la phénologie de la mue de la grande oie des neiges ainsi que le rôle des hormones et des facteurs environnementaux dans le contrôle de la mue et de la qualité des plumes. Nous avons utilisé une base de données de plus de 20 ans afin d’examiner l’effet des conditions environnementales et de la reproduction sur la phénologie de la mue, et des hormones thyroïdiennes (T3) et de stress et de la ...
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