Biology "Metabolism, Water Loss and Extreme Environments: The Ecological Physiology of Migratory and Desert-Adapted Birds"

Dr. Alexander Gerson is assistant professor of biology at the University of Massachusetts Amherst.

"Throughout their annual cycle, many birds are exposed to extreme environments, and in order to survive, they rely on unique physiological adaptations. Migratory birds travel thousands of miles between breeding and wintering grounds, and the completion of these journeys requires nonstop flights lasting from hours to days. During flight, fat is the primary fuel for endurance exercise, but protein is also catabolized. Due to this protein catabolism, long-distance migrant birds arrive after flights with organ mass reductions as great as 50 percent of the preflight mass, yet are still able to refuel in preparation for the next leg of the journey. Although this phenomenon has been documented in many species of migratory bird, the physiological consequences and ecological correlates underlying this degree of protein catabolism remain unclear. By flying birds in a climatically controlled wind tunnel, I showed that this in-flight protein catabolism is accelerated in response to warmer and dryer conditions, and thus a changing climate may pose a direct challenge to these animals' physiological ability to complete migratory flights. In a separate system, I also explore the physiological adaptations of birds living in the hottest deserts on earth. As a result of climate change, extreme heat events are becoming more frequent, and catastrophic animal die-offs are becoming common. Through a global survey of heat tolerance in birds we have identified key physiological traits that allow birds to survive these heat events, while also informing the phylogenetic breadth of heat tolerance in birds."