Where are Tucson's birds? Multiscale models, shifting baselines, and alternative futures

Abstract

Urban areas occupy a large and increasing proportion of global land area. To date, urbanization generally produces disastrous consequences for native species. Yet some developed areas appear to support native species better than others, suggesting that humans need not harm nature with their mere presence. Indeed, our cities--if managed appropriately--may play a crucial role in sustaining the world's biological diversity. Focusing on birds, I here present four investigations into the causes and consequences of, and potential solutions to, the problem of reduced biodiversity in urban areas. In the first, I develop and implement a community-based monitoring project (the Tucson Bird Count) to acquire previously unavailable data on the distribution of birds throughout Tucson and its many habitats. In the second investigation, I focus on one suite of birds--those that require desertscrub habitats--and develop a model to understand better the relationship between these species and the composition of their habitats in and around Tucson. In the third investigation, I evaluate the ability of 62 alternative future scenarios to restore and sustain Tucson's desert birds, assessing particular strategies that can be used to reduce the impact of development on these species. In the fourth investigation, I compare the displacement of humans relative to bird diversity in Tucson and 4 other cities. This analysis reveals a systematic pattern of urban humans concentrated in neighborhoods of impoverished diversity. This pattern likely applies to many other cities worldwide, and has tragic implications both for human quality of life and for the conservation of nature everywhere. Fixing this situation will require innovative approaches--based on sound biology--to sustaining nature nearer the places we spend our lives. This dissertation is a first step in that direction.