Meeting Abstract

5.5  Friday, Jan. 4  Impact of hydroelectric operations on the physiology of songbirds during Fall migration WAGNER, DN*; GREEN, DJ; COOPER, JM; LOVE, OP; WILLIAMS, TD; Univ. of Miami – RSMAS; Simon Fraser Univ.; Cooper, Beauchesne, & Associates, ltd.; Univ. of Windsor; Simon Fraser Univ. dwagner@rsmas.miami.edu

Habitat quality in riparian zones used by Neotropical passerine migrants, important during migration, will vary with changes in water level. This is an important management consideration for operation of hydroelectric facilities. We conducted a three-year study monitoring physiological condition of Fall migrants in relation to variation in water levels in four passerine species (Geothlypis trichas, Setophaga petechia, Oreothlypis celata, & Cardellina pusilla) in Revelstoke, British Columbia. Birds were blood-sampled during migration and we measured plasma metabolites (triglyceride, glycerol, & β-hydroxybutyrate) and corticosterone (CORT) as indicators of fattening rate and environmental stress, respectively. Individuals had low baseline CORT and showed a robust stress response following capture, contradicting the Migration-Modulation Hypothesis, which proposes that baseline CORT levels are elevated in migratory birds to facilitate hyperphagia and lipogenesis, and that further elevation of CORT in response to acute stress is suppressed. Additionally, there was significant annual variation in timing of the stress-induced increase in CORT, and individual variation in the rate of increase in CORT was correlated with Julian day, being higher later in the migration period. 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 also varied among years, but this was not consistently associated with high or low water levels.