Abstracts

Presented by Cheyenne R. Beach - Email: cr-beach@wiu.edu

Lipid reserves are important energy stores for endurance flights and egg production in wild birds. Plasma-lipid metabolites have been useful in assessing habitat quality for avian species during migration, particularly for wetland-obligate species. Physiological measures can provide information on whether individuals are catabolizing or accumulating lipids. Comparing known daily mass changes (DMC) with plasma-lipid metabolite concentrations provides a quantitative method to index spatial and temporal changes in lipid reserves, and thus provides a reliable technique for assessing foraging habitat quality during migration. However, there is little information regarding the effects of diet composition on metabolite concentrations. Our objective was to quantify the relationship of plasma-lipid metabolite concentrations (free triglycerides and -hydroxybutyrate; hereafter TRIG and BOHB) and diet composition. During spring migration 2017, we captured and held wild lesser scaup (Aythya affinis) in short-term captivity to control for feeding rates, amount and type of ingesta. Scaup were assigned to one of three experimental diet types (i.e., amphipods, n = 20; chironomids, n = 20; and corn, n = 19), and manually fed for the duration of captivity (~ 24 hrs). Further, we included scaup that had been fasted over duration in captivity to represent individuals that were catabolizing lipids. We obtained plasma samples upon completion of trials, froze at -20 C, and analyzed by endpoint and kinetic assays using established protocols. We used multiple linear regression to evaluate if variation in DMC was explained by TRIG and BOHB between diet types; corn diet (R^2 = 0.48, P < 0.001), chironomid diet (R^2 = 0.13, P = 0.03), and amphipod diet (R^2 = 0.07, P = 0.18). Though we are awaiting results from proximate analysis on diet nutritional values, our preliminary results suggest that diet may influence plasma-lipid metabolite concentrations and therefore, the ability to predict short-term mass changes in lesser scaup.