Dissertation Research: Future changes in California bird communities projected from century-scale resurveys

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This project will examine why birds in California occur in different places than they did 100 years ago. This information will be used to predict how birds will respond to future changes in climate and habitat, enabling better conservation planning. Researchers will make use of a unique historic resource: systematic surveys of birds conducted in every major ecological region of California from 1900 to 1945. These surveys were conducted at sites that have since experienced changes in climate, agricultural development, and urbanization. Thirty sites in the Los Angeles area will be re-surveyed. The resulting data will be added to a dataset of 290 sites already re-surveyed in the Sierra Nevada, Coast Ranges, Central Valley, and Mojave Desert. Measures of how birds have responded to changes at each site will be used to predict future responses to climate and land use change. This study will enhance our understanding of how combined changes in climate and land use impact birds. Specifically, it will test whether changes in land use exacerbate problems from climate change or help some birds to live in places they would have otherwise avoided. This project is important for conservation planning and will provide training and mentoring of two students.This study will use a unique historical resource (early 20th century bird surveys conducted by Joseph Grinnell and colleagues) in conjunction with contemporary resurveys to quantify how the effects of climate and land-use change have altered bird distributions in California. These measures will be used to project bird distributions under future scenarios of climate and land-use change. Re-surveys have already been completed at 30 sites in the agriculturally-developed Central Valley, and 260 relatively protected sites in the Sierra Nevada, Coast Ranges, and Mojave Desert. This project will re-resurvey an additional 30 sites in the Los Angeles area, providing a measure of how birds have responded to greater warming and urbanization than is represented in the current dataset. By quantifying how changes in bird occupancy over the past century are driven by climate and land-use covariates, this study will then project bird responses to future scenarios of climate and land-use change based on direct measures of temporal change. Projections will be used to explore which groups of birds are expected to experience range expansions or contractions in the future, and whether this will result in the creation of no-analog bird communities.