Neotropical Winter Habitat of the Magnolia Warbler: Effects on Molt, Energetic Condition, Migration Timing, and Hematozoan Infection During Spring Migration

Abstract

Abstract. Events in one season can have carryover effects on birds in a subsequent season. Little research has addressed how conditions where a bird winters influence it during migration. We investigated such carryover effects on Magnolia Warblers (Dendroica magnolia) captured during spring migration in northwestern Ohio. We examined signatures of stable carbon isotopes (δ13C) in feathers grown in the neotropics where the birds winter and hypothesized that drier habitats (as indicated by δ13C) would advance infection by avian hematozoa, delay migration, and depress energetic condition and extent of prealternate molt. The range of δ13C in feathers (-25.0‰ to -19.9‰) was similar to that published for tissues grown in winter by other nearctic-neotropical migrant songbirds, suggesting that the Magnolia Warblers we captured wintered over a range of xeric to mesic habitats. Nonetheless, we detected no significant relationships between habitat moisture (as indicated by δ13C in feathers) and spring migration timi...