Rapid warming of the Earth's surface and predictions of significant increases in the frequency, intensity and duration of heat waves suggests the potential for large impacts on animal communities. Although little studied, among the most important direct effects of global warming on desert animals may be catastrophic mortality associated with extreme heat waves. Although they have yet to impact deserts of the southwestern United States, recent reports from Australia, India and South Africa indicate that bird die-offs due to heat stress are occurring with increasing frequency. This research seeks to link physiological and behavioral mechanisms of heat tolerance in birds to changes in populations and communities in response to global warming. This project will characterize individual and species level variation in heat tolerance and how it is modified by hydration status in birds across three continents in the field and laboratory. By sampling species that differ in body size, ecology and evolutionary history and diversity, this research will provide the information needed to develop predictive models that estimate impacts of future climates on bird species, and communities. Currently, there is only anecdotal information on the natural history and physiological ecology of catastrophic die-offs and the factors that potentially mitigate or exacerbate the effects on desert bird communities. To understand this phenomenon and how desert bird communities differ on a global scale, this study will examine the behavioral and physiological responses to heat waves as a function of body size, diet, relative reliance on free water resources and structure of bird communities on three continents. Data will also be collected on the physiological status, behavior and pathology of birds in Australia during mortality events, which will be compared to laboratory findings to provide an integrated view of the natural history of heat waves and their effects on bird communities. This proposal represents an international approach to understanding the direct effects of climate on bird communities. This collaboration will foster a better understanding of the ongoing effects of climate change on a global scale and the generalized findings will be applicable to all bird communities. The project will provide opportunities for undergraduate and graduate students to travel and interact with researchers from Africa and Australia. The University of New Mexico is a Hispanic serving institution and Hispanic and Native American undergraduate students will be engaged in research through the NSF REU program. This research will inform natural resource managers by providing risk assessments for species and regions. Climate change is a global problem and because bird communities are likely to be differentially impacted by factors such as body size distributions, dietary guilds, and the availability of free water resources, findings from this research will improve understanding of how climate events will modify bird communities and thus the ecosystem services (such as pollination and seed dispersal) that they provide. Research describing the pathogenesis of heatstroke in birds will be of great interest to veterinarians, comparative biologists and medical researchers, and has the potential to provide biomarkers for identifying heatstroke in birds.