. J H.During her five.year Presidential Young Investigator award, Dr. Root, University of Michigan, plans to continue investigating the factors affecting the distribution and abundance patterns of all birds wintering in North America. Two major studies are proposed. Initially, Dr. Root will investigate various physiological mechanisms that may cause winter ambient temperatures to shape the northern range boundaries of some birds. Metabolic rates and various energy.storage and energy.use characteristics will be compared among several species at different sites along cross.continental, latitudinal transects. Study 2 will use the physiological information obtained in the first study to investigate the possible effect of global warming on avian biogeographical patterns. This will involve the development of a theoretical model that addresses how the winter ranges of birds change, given a particular shift in ambient temperature. Such a model could not only provide insight about the basic biology of North American avian communities, but also suggest management strategies for combating the negative impacts of climate change.
