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CONFERENCE SCHEDULE UPDATES & CHANGES: As a result of the prolonged government shutdown, we experienced a number of cancellations and changes to the schedule. Cancellations and changes are listed here (as of January 26, 2019). 

Tuesday, January 29 • 6:00pm - 9:00pm
(P86) Using Plasma-lipid Metabolites to Index Mass Changes in Birds: Are Triglycerides More Indicative of Energy Income Than Deposition?

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AUTHORS. Eric Smith, Western Illinois University; Michael Anteau, U.S. Geological Survey; Heath Hagy, U.S. Fish & Wildlife Service; Christopher Jacques, Western Illinois University

ABSTRACT. During spring migration, energy acquisition and storage are important for survival during resource-limited periods, endurance flights, and reproduction. Plasma-lipid metabolites (triglyceride [TRIG], β-hydroxybutyrate [BOHB]) have been used to index changes in lipid reserves over short-time periods, thus have utility for assessing foraging habitat quality at stopover sites. However, such an index may be affected by energetic maintenance costs and further validation under experimental conditions is needed to understand potential sources of variation. We evaluated a previous index using wild lesser scaup (Aythya affinis; hereafter scaup) held in short-term captivity (24 hr) during spring migration through Illinois, USA. β-hydroxybutyrate was negatively associated and TRIG was positively associated with changes in body mass (R<sup>2</sup> = 0.68). Our BOHB slope estimate was nearly identical to one published previously on free-living scaup. However, effects of TRIG differed from free-living scaup and varied by sex, with females having a greater slope. Our results suggest that TRIG is a better measure of energy income than deposition because TRIG slopes appear to be sensitive to energetic maintenance costs. In contrast, BOHB appears to be reliable in predicting negative mass change which is consistent with previous findings. Despite differences in TRIG slopes, our cross-validation process using z-standardized predictions from captive and free-living scaup corresponded well and there was no directional bias (r<sup>2</sup> = 0.79). Sexual differences in apparent lipid deposition rates warrant further research before a generalizable model is advisable for comparing mass change predictions across studies. However, if predictions are standardized it appears this technique is generally robust to variations in energy income vs. deposition. Our evaluation provides verification for the utility of plasma-lipid metabolites as an indicator of short-term mass change and as a potential index of foraging habitat quality.

Tuesday January 29, 2019 6:00pm - 9:00pm
SUPERIOR BALLROOM C/D

Attendees (3)