Biologists use current and historical bird surveys to reveal how land use change has amplified — and in some cases mitigated — the impacts of climate change on bird populations in Los Angeles and the Central Valley over the past century. The study found that urbanization and much hotter and drier conditions in L.A. have driven declines in more than one-third of bird species in the region.Biologists use current and historical bird surveys to reveal how land use change has amplified — and in some cases mitigated — the impacts of climate change on bird populations in Los Angeles and the Central Valley over the past century. The study found that urbanization and much hotter and drier conditions in L.A. have driven declines in more than one-third of bird species in the region.