Principal Investigators: Dr. Scott R. McWilliams, Associate Professor, University of Rhode Island Dr. Barbara J. Pierce, Assistant Professor, Sacred Heart University
Project Number: IOS-0748349
Project Title: Interactive effects of dietary fatty acids and antioxidants on diet choices, metabolism, and exercise performance of birds
Abstract: Athletes train and eat to increase their capacity to perform on demand. A major gap in our understanding of the ecology and physiology of wild animals is how biochemical, physiological, and behavioral processes interact to affect whole-animal performance. The investigators will experimentally determine how dietary fats and antioxidants influence diet choices, metabolism, and exercise performance of migratory birds. Two species of migratory songbird will be fed diets with certain types of fats and antioxidants. The investigators then measure the metabolism and energy expenditure of these migratory birds during short-intense exercise, like that used to escape predators, and during long-duration migratory flights in a wind tunnel. The investigators will also determine if birds choose their diets to achieve some optimum fat composition, and whether this depends on the condition of the bird or the concentration of antioxidants in the diet. The research will be conducted by a vertically-integrated research team comprised of members from a large state research university (USA), a small private university (USA), and the Max Planck Institute for Ornithology (Germany) so that participants gain experience working within a diversity of educational and research settings. Society at large will benefit from this research because there is much current interest in dietary antioxidants and how they may promote human health, and migratory birds offer an interesting model system for studying the effects of dietary antioxidants and fat composition on exercise performance of a vertebrate. Also, understanding the nutritional ecology of migratory songbirds is critical because many songbird populations are declining, because migratory birds are implicated as dispersers of disease, and because many of the sites used by birds during their migration are threatened by development or disturbance by humans. Thus, this fundamental research on diet choices and exercise performance of migratory songbirds has important implications for wildlife conservation and human health.
" has produced many important results, raised many new questions, and has impacted a broad audience that includes our scientific peers, the general public, a diversity of students at many levels (middle school through graduate school), and conservation biologists interested in conserving and managing habitat for migratory birds. Our project was a blend of (a) tightly-controlled experiments that involved flying songbirds in the best windtunnels in the world for simulating long-duration flights of songbirds while we investigated how dietary fats and antioxidants influenced their metabolism and exercise performance; (b) short-term captive-bird studies that tested hypotheses about how dietary antioxidants and the endogenous antioxidant system of birds responds to ecologically-relevant challenges such as fasting and exercise; and (c) field studies of free-living songbirds at stopover sites during migration to determine how wild birds cope with the oxidative stress associated with fueling long-duration migratory flights with fats. We found that the types of fatty acids consumed by birds directly affects the composition of their fat stores, and that this in turn affected their exercise performance. We identified several physiological mechanisms for how fat quality affects exercise performance of migratory songbirds, and this is the primary focus of our future work. We also found that many species of songbirds consume fruits during migration and, at least during fall migration along the southern New England coast, migrating songbirds prefer to consume fruits that have more dietary antioxidants (Figure 1). These results are consistent with the hypothesis that free-living birds select antioxidant-rich fruits during autumn migration to protect themselves against the potentially damaging effects of oxidative stress caused by long-distance fasting flight. Our studies also revealed that migratory birds successfully mitigate oxidative damage associated with exercise by upregulating their endogenous antioxidant system which includes increased production of uric acid and the activity of key liver antioxidant enzymes. Moreover, we found that constitutive immune function was compromised in birds immediately after long-duration flights but recovered within 48 hrs of the flight. In general, these findings emphasize the importance of studying animals as integrated physiological systems (Figure 2) because, in the case of migratory birds during long-duration flights, there are clearly important interactions between the physiological systems involved in oxidative balance, energy metabolism, and the immune system. The funding from this project supported national and international collaborations between scientists from four countries, as well as the training of three post-docs, six graduate students, and 14 undergraduate students. Most of the post-docs and graduate students, and two of the undergraduates performed their work internationally at the Max Planck Institute for Ornithology in Seewiesen, Germany, and the Advanced Facility for Avian Research, in Western Ontario, Canada. This project has resulted in twenty-five published research articles, one published book chapter and several manuscripts in preparation. We have shared our results as invited speakers or presenters at more than 27 scientific meetings or other academic venues throughout the world. Our broader impacts also include direct involvement with local schools and non-governmental organizations. We have worked with local secondary schools in developing and teaching units on the effects of climate change on migratory birds as well as the role of women in science in the field of avian research. We have given public lectures on this research to audiences that include local garden clubs, birding organizations, and conservation groups. The results from this project have appeared in the mainstream media and have been highlighted by our respective university’s alumni magazines and other popular outlets.
