Plasma metabolites reveal changes in physiological state of Eared Grebes (Podiceps nigricollis) during three non-migratory periods

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Yoshida, Allison A
plasma metabolites; eared grebes; waterbirds; triglycerides; migratory birds; physiological state; Exercise Physiology; Life Sciences; Marine Biology; Ornithology; Poultry or Avian Science; Terrestrial and Aquatic Ecology; Zoology
thesis / dissertation description
Energy storage and use during the annual cycle of migratory birds is dynamic especially during migration. However, considerable amounts of the annual cycle are spent not migrating, and the physiological state of birds during these non-migratory periods is not well understood. We compared plasma metabolites (TRIG, BUTY, URIC, GLY) in Eared Grebes (Podiceps nigricollis) residing at three important areas when they are not migrating: fall staging (postbreeding at Mono Lake, California), spring staging (pre-breeding at Great Salt Lake, Utah), and an extended stopover prior to spring staging (Salton Sea, California). Plasma metabolites were also measured in resting and active grebes while staging at Great Salt Lake. As expected, grebes held overnight without food had decreased plasma TRIG and URIC, but elevated plasma BUTY, compared to active grebes. Grebes showed the greatest change in physiological state during late-winter at Salton Sea, California when elevated plasma TRIG levels indicated increased fat deposition. Body mass in Eared Grebes was positively correlated to plasma TRIG and URIC at the two staging areas, but not the extended stopover site. Differences in physiological state during non-migratory periods over the annual cycle of Eared Grebes puts current plasma metabolite studies during migration periods into context and provides an example of the importance of nonmigratory periods for acquisition of nutrient stores.