Migration physiology and energetics of birds and bats

候鸟和蝙蝠面临着极端的生理挑战。飞行过程中的能量消耗异常高，迁徙者在没有水、食物或休息的情况下持续飞行数小时、数天甚至超过一周。他们经常在高海拔飞行，以获得顺风的帮助，迫使他们在稀薄的空气中进行高强度的低氧运动。当他们停下来加油时，他们的活动水平很高，吃和消化食物。候鸟在加油时吃的东西可能对飞行表现很重要。特别是omega-3脂肪酸已经被假设可以改善滨鸟的能量代谢。迁徙的蝙蝠和一些鸟类（蜂鸟）在中途停留时使用冬眠（将体温和新陈代谢降至最低水平），以便在它们无法进食的栖息期间尽量减少脂肪的损失。在这些物种中，休眠是如何开启和关闭的尚不清楚。我研究的长期目标是了解候鸟和蝙蝠的耐力飞行和加油的能量学和生理学，以及这些是如何受到内在因素（季节、性别、年龄）和外在条件（海拔、温度、湿度、饮食、疾病和污染物）的影响的。在短期内，我们将研究：1)鸣禽和滨鸟在高海拔飞行的生理机制；2)飞行过程中使用呼吸中的稳定同位素（13C富集）的能量成本和燃料基质氧化；3)生物膜摄食和omega-3脂肪酸对滨鸟迁徙的重要性；4)迁徙鸟类和蝙蝠的肌肉细胞（线粒体）如何专门用于飞行和冬眠；5)超耐力飞行者的特殊生理。我们将使用专门的设备和技术进行拟议的研究。一个专门为鸟类设计的独特的低压气候风洞将用于测试不同物种、性别和年龄的高海拔飞行的生理影响和能量消耗。呼吸中的碳同位素将使用光谱分析仪实时测量。自动化的地面和卫星无线电遥测将用于跟踪鸟类在实验操纵它们的饮食后的迁徙。在剧烈运动中，线粒体功能和自由基会损害细胞，将通过高分辨率呼吸计测量。该研究计划将培养15 - 20名高素质人才，提高基础知识，并具有实际意义的保护迁徙物种。自1970年以来，北美的鸟类数量下降了30%，加拿大的长途候鸟面临的风险最大。在风能开发过程中，迁徙蝙蝠的死亡率会升高，而且对它们的研究很少。这项研究将提高我们对这些动物迁徙方式的理解，从而帮助我们保护它们。

Migratory birds and bats face extreme physiological challenges. Energy expenditure during flight is exceptionally high, and migrants sustain flight for many hours, days and even over a week without water, food or rest. They often fly at high altitudes in order to gain the assistance of tailwinds, forcing them to exercise intensely in thin air with low oxygen. When they stop to refuel they have high levels of activity, eating and digesting food. What migrants eat during refueling may be important for flight performance. In particular omega-3 fatty acids have been hypothesized to improve energy metabolism in shorebirds. Migrating bats and some birds (hummingbirds) use torpor (decreasing body temperature and metabolism to minimal levels) at stopovers to minimize the loss of fat during roosting periods when they are unable to feed. How torpor is switched on and off in these species is not known. The long term objective of my research is to understand the energetics and physiology of endurance flight and refueling of migratory birds and bats, and how these are affected by intrinsic factors (season, sex, age) and extrinsic conditions (altitude, temperature, humidity, diet, disease, and pollutants). In the short term we will study: 1) the physiological mechanisms that allow songbirds and shorebirds to fly at high altitudes; 2) energy costs and fuel substrate oxidation during flight using stable isotopes (13C enrichment) in breath; 3) the importance of biofilm feeding and omega-3 fatty acids for migration in shorebirds; 4) how the powerhouses of muscle cells (mitochondria) may be specialized for flight and torpor in migratory birds and bats; 5)the specialized physiology of ultra-endurance fliers. We will use specialized facilities and technologies for the proposed research. A unique hypobaric, climatic wind tunnel, specifically designed for birds, will be used to test the physiological effects of high altitude flight and energy costs in different species, sexes and ages. Carbon isotopes in breath will be measured in real time using a spectroscopic analyzer. Automated ground-based and satellite radio-telemetry will be used to track bird migrations after experimental manipulation of their diets. Mitochondrial function and free radicals that can damage cells during intense exercise will be measured by high-resolution respirometry. The research program will train 15 - 20 highly qualified personnel, advance basic knowledge, and have practical relevance for the conservation of migratory species. North American bird populations have declined by 30% since 1970, and Canada's long-distance migrants are at the greatest risk. Migratory bats are at elevated risk for mortality at wind energy developments, and they are very poorly studied. This research will improve our understanding of why these animals migrate the way they do, and thus help us protect them.