Migration Physiology of Birds and Bats

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Migration is one of the most physiologically demanding activities animals perform. This is particularly true for fliers because flight energy expenditure is exceptionally high, flights are maintained for long periods (many hours, but up to 9 days without water, food or rest), and refueling demands high levels of activity and nutrient processing. The allocation of energy and nutrients to migration may impair other functions, such as immunity against diseases or parasites, and conversely, immune or toxic challenges may impede migration. Thus, migration offers an excellent model to study the limits to physiological performance of animals. The long term objective of my proposed research program is to understand how environmental factors, such as atmospheric conditions, disease, pollutants, and habitat quality, influence the physiological mechanisms and trade-offs that govern the abilities of birds and bats to migrate. My short term objectives are: 1) to establish methods in my lab to use stable isotopes (13C enrichment) in breath to measure metabolic rate and fuel oxidation during flight; 2) to measure how variation in altitude affects flight energetics, gas exchange, metabolism, water balance, and kinematics in birds; 3) to use paired lab/field experiments to study effects of diet, muscle fatty acid transporters, malarial infection, and mercury on migratory flight and stopover in birds; and 4) to test the hypothesis that energy consumption during roosting is insensitive to ambient temperature in migrating bats at stopover. We will use exciting new facilities and technologies for the proposed research. A unique hypobaric, climatic wind tunnel, specifically designed for birds, will be used to study the effects of high altitude on the biomechanics and physiology of flight and migration. A mobile field laboratory and a large-scale automated radio-telemetry array will be used to experimentally manipulate the diets, muscle physiology, disease status and mercury burdens of migratory birds, and track their migrations over 40,000 km2 in southwest Ontario. We will use leading-edge molecular biology techniques to specifically reduce the expression of key proteins in bird flight muscles to test their importance for migration. The research program will train 15 – 20 highly qualified personnel, advance basic knowledge, and have practical applications for the conservation of migratory species. About 80% of Canada’s birds migrate, and many populations are declining. Canada’s migratory bats are very poorly studied, and are at elevated risk for mortality at wind energy developments. This research will improve our understanding of these animals, and provide insight into important problems, such as the potential for climate change to affect migratory flight, the ability of migratory birds to spread zoonotic diseases over long distances, and the effects of mercury contamination in boreal forests.