HABITAT LOSS, FRAGMENTATION AND CLIMATIC DRIVERS OF AVIAN DIVERSITY ACROSS THE ANDES AND IMPLICATIONS FOR CLIMATE CHANGE A Dissertation Presented to the Faculty of the Graduate School of Cornell University In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy by Cristian Steven Sevillano-Ríos May 2020 © 2020 Cristian Steven Sevillano-Ríos HABITAT LOSS, FRAGMENTATION AND CLIMATIC DRIVERS OF AVIAN DIVERSITY ACROSS THE ANDES AND THEIR IMPLICATIONS FOR CLIMATE CHANGE Cristian Steven Sevillano-Ríos, Ph. D Cornell University 2020 ABSTRACT The diversity of life on our planet is under siege. Around the world habitat loss, degradation, and fragmentation are among the main threats to biodiversity, with negative outcomes exacerbated by climate change. Our poor understanding of the mechanisms governing ecological responses to global change, especially in tropical montane systems, constrains our ability to predict and mitigate these threats to biodiversity. This dissertation addresses the effects of habitat loss, fragmentation and climatic drivers on avian diversity across the Andes, with a special focus on the implications for climate change. Specifically, we examined (1) sensitivity of birds to forest cover and patch size within one of the most threatened ecosystems of the Andes, Polylepis forests, (2) how factors related to climate, landscape configuration and human activities at regional scales shape patterns of avian species richness and endemism along elevational gradients in the western slope of the Andes, (3) the extent to which relationships between elevation and avian diversity at continental scales are influenced by complex interactions between temperature and precipitation, and (4) the degree to which avian communities in the Andes can persist under future climate scenarios. We surveyed 88 bird species across 59 Polylepis patches within five glacier ii valleys (3,300 to 4,700 m a.s.l.) of Cordillera Blanca (Ancash-Peru). We also compiled elevational ranges of 212 species within the region and 2,384 across the continent, together with climatic and environmental covariables across 16 elevational gradients across the Andes of Colombia, Ecuador, Peru, Bolivia, Argentina and Chile. At landscape scales, avian communities at high elevations seemed adapted to naturally patchy Polylepis landscapes. Species richness was greatest within small fragments and areas with reduced forest cover. Polylepis specialists persisted within small patches, as long as landscapes retained more than 10% of forest (>400 ha) within glacial valleys. At regional scales along the western slope of the Central Andes (Ancash, Peru), avian species richness and endemism peaked at mid-elevations (3,300 – 4,300 masl) where temperatures and precipitation were comparably moderate (i.e, intermediate levels). At continental scales, the influence of climatic factors on elevational diversity gradients differed between xeric and mesic slopes. Diversity gradients were best explained by the interaction between temperature and precipitation along the xeric slopes of the western central Andes of Peru and Chile, but primarily by temperature along mesic slopes, like the East slope to the Amazon. Based upon four climate scenarios for 2070, changes in temperature and precipitation in the western central Andes will be most severe above 2,000 masl, whereas human activities will intensify and expand below 500 and above 3,000 masl. Collectively, these results provide evidence for three overarching conclusions: 1) even fragmented or heterogeneous Polylepis landscapes have potential to adequately support avian communities in High Andean systems as well as provide habitat for numerous species of conservation concern; 2) elevational gradients in avian diversity across the Andes iii seem to be shaped more than by climatic than landscape or social factors; and 3) future changes in climate may profoundly alter the current avian communities, and efforts to forecast the consequences of climate change using temperature alone can produce misleading results, especially in xeric regions. iv BIOGRAPHICAL SKETCH C. Steven Sevillano-Ríos was born in the city of Huaraz, a city within the Cordillera Blanca of Peru, where, from an early age, he was in close contact with nature. Steven’s interest in nature and ecology was kindled by his parents, Cristian Sevillano and Nini Rios, who shared their sightseeing tours and traveled frequently with him and his two brothers, Sebastian, and Adrian to different natural parts of Peru. During his last years at school, Steven met Professor Nini Sanchez, a true pedagogue of yore, which few are now, who sparked his great interest in the natural sciences and reaffirmed his wish to study biology. Steven studied biology at Cayetano Heredia University in Lima, where his advisor, Dr. Armando Valdés-Velásques introduced him to the scientific world of ecology. Twice during his college career, Steven was forced to interrupt his studies in order to take care of family affairs - for rheumatic fever affecting his father in March of 2002 and his mother’s diagnosis with breast cancer in 2006. Thankfully, both recovered well and despite these interruptions, Steven completed his bachelor’s in biology in 2007. Steven always hoped that he would one day apply his knowledge to his birthplace, Cordillera Blanca and mountains in general. Thus, after finishing his BS degree, he conducted his undergrad thesis research in Huascarán National Park, working with the incredible Polylepis forests and its birds. Steven also developed several projects through the Mountain Institute in order to disseminate knowledge about the goods and services provided by Polylepis forests and their potential for sustainable use. After publishing the results of his research, Steven frequently gave talks at conferences and workshops about Polylepis, and he helped to create a community conservation area in the Cordillera Huayhuash. v Soon thereafter, Steven moved to southern Peru in order to explore new opportunities. Working on Manu National Park, Tambopata National Park, and Bahuaja Sonene National Park, three of the most biodiverse areas of the world provided Steven with the incredible opportunity to learn from nature, especially from birds, and to realize that he could expand the ecological knowledge of poorly understood natural systems. At Wayquecha Biological Station, he learned from Dr. Huw Lloyd and several graduate students that were conducting fieldwork. During his time with Wildlife Conservation Society’s (WCS) in the Alto Tambopata Landscape Project, he worked with coffee farmers and local people to facilitate conservation of these natural areas. He also co-coordinated two rapid biological assessments in very remote Amazon areas. While there, Steven saw first-hand the massive destruction of biological richness by illegal mining, unrestricted burning and the use of land for cultivation of illegal crops. Between 2014 - 2016, Steven, as Fulbright Fellow, received his Master degree in Natural Resources at Cornell University under the guidance of Dr. Amanda Rodewald. In 2016, Steven transitioned to the doctoral program at Cornell, thanks to a fellowship from the Peruvian CONCYTEC. To date, he has published 14 research articles (7 as the first author), 2 theses, 2 book chapters, with more on the way (1 article in review, 1 in press and 4 in preparation). In September 2019, Steven started to work as Resident Lecturer in Conservation Science at the School for Field Studies in the Center for Amazonian Studies in Peru, and in May 2020 he started a postdoc position in Peru where he looks forward to further personal and professional development. vi I dedicate this work to my loving family, Nini Rios de Sevillano, Cristian Sevillano, Sebastian Sevillano, and Adrian Sevillano. vii Ilustration: Katterine Sandoval ACKNOWLEDGMENTS This dissertation was made possible by the effort, enthusiasm, generosity, and support of many institutions and people, including biologists, ecologists, conservationists, many friends, and my family. For the financial support, I am grateful to the FONDECYT- CONCYTEC Scholarship from the Peruvian Government and to the Athena Grant, the Bergstrom Award of the Association of Field Ornithologists, Fulbright Scholarship and the American Alpine Club Research Grants 2017 without whose funding, this research and my studies would not have been possible. I also extend gratitude to members of my committee. To Stephen Morreale for accepting this challenge and for the critical and intensive discussions that improved my research and always challenged my understanding and scientific knowledge. You were a great support during all these years, including your support at the Cornell Tropical Biology and Conservation Graduate Student Association. To André Dhondt for his insightful questions, comments, and suggestions about the ecology and biology of mountain birds. To Viviana Ruíz-Gutierrez for encouraging me to think deeply about my ecological questions, the ways to test and analyzing them and the ways of how I can apply this knowledge across South America. Finally, to my advisor, Amanda Rodewald, who from our first discussions showed a great interest in my study in Peru and has been extraordinarily supportive during all these years at Cornell and as part of the Lab of Ornithology. Thank you for guiding me and facilitating many processes of my research, from strengthening my theoretical background to promoting critical thinking so helpful now and definitely in my future. Thank you!