Tundra Swans (Cygnus columbianus) spend a substantial portion of their annual cycle at migratory staging areas. Despite the potential importance of staging areas to conservation of Eastern Population (EP) Tundra Swans, few data are available to assess life-history strategies of the species during migration. During 1999 and 2000, 48 adult Tundra Swans were collected during peak periods of spring and autumn migration at Long Point, Ontario, Canada, to establish baselines on nutrient reserve levels and morphology of digestive organs. Results were compared to nutrient reserve data for EP Tundra Swans collected at a major wintering area in North Carolina, USA. Lipid reserve levels did not differ between sexes nor varied with body size, but lipid reserves were approximately two times greater in autumn than spring. Males had greater protein reserves than females, and protein reserves were similar during autumn and spring. Although digestive organs were predicted to be longer and heavier during autumn, no seasonal variation in digestive organs was detected. Lipid reserve levels of Tundra Swans at Long Point during spring were similar to those recorded for wintering birds in North Carolina, suggesting that lipid reserves catabolized from autumn through winter were not replenished prior to arriving at this initial spring staging area. The results highlight the importance of managing quality aquatic and terrestrial foraging habitats at staging areas for conservation EP Tundra Swans.
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Vol. 34 • No. 4