Habitat quality in riparian zones used by Neotropical migrants, important for migration success, will vary with changes in water level, an important management consideration for operation of hydroelectric facilities. I conducted a three-year study monitoring physiological condition of Fall migrants in relation to variation in water levels in four passerine species in Revelstoke, BC. Birds were blood sampled during migration and I measured plasma metabolites (triglyceride, glycerol, & β-hydroxybutyrate) and corticosterone (CORT) as indicators of fattening rate and environmental stress, respectively. Migrants had low baseline CORT and showed a robust stress response following capture, contradicting the Migration-Modulation Hypothesis. Estimated fattening rate (triglyceride) increased with time of day and date, reflecting diurnal and seasonal variation in fattening, and among species. However, fattening rate did not vary among-years despite marked annual variation in water levels. Plasma glycerol and β-hydroxybutyrate varied among years, but this was not consistently associated with high or low water levels.
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Thesis advisor: Williams, Tony
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