Meeting Abstract
67.4 Thursday, Jan. 6 Impact of water level management on the condition of migratory songbirds WAGNER, DN*; GREEN, D; COOPER, JM; BEAUCHESNE, S; WILLIAMS, TD; Simon Fraser University; Simon Fraser University; Cooper, Beauchesne, & Associates LTD.; Cooper, Beauchesne, & Associates LTD.; Simon Fraser University dnw1@sfu.ca
Habitat quality is thought to be important for migratory success in many neo-tropical migrants. Both the quantity and quality of riparian habitats used by migrants will vary with changes in water level and this can be an important management consideration for operation of dams and reservoirs. We have completed the initial 2 years of a 10-year study monitoring the timing and pattern of Fall migration in four potentially dam-impacted neo-tropical migratory warbler species (Yellow Warblers, Dendroica petechia; Common Yellowthroat, Geothlypis trichas; Wilson’s Warbler, Wilsonia pusilla; Orange-crowned Warbler, Vermivora celata) in a riparian zone in Revelstoke, British Columbia. We blood sampled birds over a 10-week period (July-September) and measured levels of plasma metabolites (triglyceride, glycerol, & β-OH butyrate) as indicators of migratory condition and fattening rate. In addition we are using stable isotope analysis to identify residents and migrants to determine how this effects variation in habitat use and rate and timing of migratory fattening. Preliminary data analysis has confirmed few age or sex differences in plasma metabolite levels (as found in previous studies). However, we do detect significant increases in fattening rate (residual triglyceride) both over the course of a single day, with time after dawn, as well as with date over the length of the migration season. Fattening rates varied significantly between the four different species of migrants, being highest in Wilson’s Warbler. In addition, there was a significant difference in average fattening rate from year to year in all four species. Average fattening rates tended to be higher in the year with higher rainfall and dam-flow rate than in the year with lower rainfall and dam-flow rate.
