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LIFE HISTORY AND ENVIRONMENTAL CORRELATES OF SURVIVAL RATES IN TROPICAL BIRDS by Micah Noel Scholer B.Sc., University of Minnesota, 2005 M.Sc., Boise State University, 2011 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Zoology) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) April 2020 © Micah Noel Scholer, 2020 The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the dissertation entitled: Life history and environmental correlates of survival rates in tropical birds Submitted by Micah Noel Scholer in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Zoology Examining Committee: Jill Jankowski Supervisor Peter Arcese Co-supervisor Mary O’Connor University Examiner Jennifer Williams University Examiner Bridget Stutchbury External Examiner Additional Supervisory Committee Members: Doug Altshuler Supervisory Committee Member Jedediah Brodie Supervisory Committee Member Kathy Martin Supervisory Committee Member ii Abstract Current thinking suggests that survival, and consequently lifespan of organisms, can be understood in terms of trade-offs between self-maintenance and reproduction, and constraints imposed by physiological mechanisms, such as metabolic intensity. While comparative studies show that many life history traits covary predictably with climate, few studies have examined variation in survival across latitudinal or elevational gradients. I paired survival rates with reproductive, morphological, behavioral, and physiological traits, as well as environmental variables to quantify the intrinsic and extrinsic drivers shaping avian life histories. In Chapter 2 I ask whether tropical birds around the world are longer lived than their temperate counterparts. My results suggested an inverse relationship between latitude and survival in the northern hemisphere, but this pattern is dampened or absent for the majority of southern hemisphere species. I also showed that extrinsic factors related to climate were poor predictors of survival compared to latitude alone, and that the relationship between survival and latitude is strongly mediated by intrinsic traits ― larger, non-migratory species with smaller clutch size had the highest survival. In Chapter 3 I focus within the Neotropics to examine how a basic physiological trait (basal metabolic rate; BMR) is linked to survival of montane and lowland birds. I found that lower BMR predicted higher survival, regardless of the elevation at which species occurred. In addition, elevation had a direct negative effect on survival, perhaps due to harsher abiotic conditions, low site fidelity, or both at higher elevations. To help facilitate estimates of age-specific survival in future studies, I determined the molt ageing criteria for South American manakin species in Chapter 4, which can be used to distinguish juveniles from adults. Like many temperate species, the occurrence of a partial preformative molt allowed iii separation of age classes based on the presence of molt limits. By drawing on both variation within the tropics and across birds globally, this dissertation provides new evidence of the connections between the high survival rate of tropical birds, their life history traits, and the environment. iv Lay summary Why do some species live longer than others? In this dissertation I look at how differences in life history traits and the environment impact avian survival, and hence, lifespan. I showed that the longest-lived bird species are those with large body size that lay fewer eggs. I also found that survival is generally higher for birds from tropical ecosystems, and that this effect is strongest in songbirds. I go on to demonstrate that the lower energy metabolism of species inhabiting tropical rainforests, which are warmer and less seasonal than northern latitudes, may help explain the higher survival of birds living near the equator. To help facilitate estimates of age-specific survival in future studies, I determined the molt ageing criteria for South American manakin species, which can be used to distinguish juveniles from adults. v Preface The dissertation work presented here is based on original and independent research by the author, Micah Noel Scholer. Work for Chapter 2 was conducted in collaboration with Matt Strimas-Mackey. I conceived the ideas, designed methodology, collected data, conducted analyses and wrote the paper. Matt Strimas-Mackey assisted with the analysis and delineating species ranges using eBird data. Jill Jankowski contributed ideas during the design and write-up phase. A version of Chapter 3 has been published: Scholer, M.N., P. Arcese, G.A. Londoño, M. Puterman, and J.E. Jankowski. 2019. Survival is negatively related to basal metabolic rate in tropical Andean birds. Functional Ecology 31: 1436–1445. I conceived the ideas, designed methodology, collected field data on survival between 2014–2016, conducted statistical analysis and wrote the paper. Gustavo Londoño and Jill Jankowski collected data on survival and basal metabolic rate from 2011–2013. Martin Puterman helped analyze the data. Jill Jankowski and Peter Arcese helped design the study and contributed ideas during the write-up phase. Work for Chapter 4 was conducted in collaboration with Jeremiah Kennedy and Blaine Carnes. I designed the study, collected data, conducted statistical analyses and wrote the paper. Blaine Carnes and Jeremiah Kennedy helped with data collection and preparing species accounts. Jill Jankowski supervised the study and provided ideas during the write-up phase. All protocols involving the use of animals in this dissertation were approved by the UBC animal care committee (A15-0067, Species ranges and diversity of tropical birds). Permits to conduct research within South America were obtained through Peru’s National Forest and Wildlife Service (SERFOR research permits no. 242-2015, 343-2016). vi Table of contents Abstract ......................................................................................................................................... iii Lay summary ..................................................................................................................................v Preface ........................................................................................................................................... vi Table of contents ......................................................................................................................... vii List of tables.................................................................................................................................. xi List of figures .............................................................................................................................. xiii Acknowledgements ......................................................................................................................xv Dedication .................................................................................................................................. xvii Chapter 1: Introduction ................................................................................................................1 1.1 Background ..........................................................................................................................1 1.2 Environmental variability and the use of climate gradients in life-history studies..............3 1.3 Research conducted for this dissertation..............................................................................6 1.3.1 Linking survival, environment, and life history traits..............................................6 1.3.2 Developing tools to improve survival estimates ......................................................8 1.3.3 Conclusions ..............................................................................................................9 1.4 Summary ............................................................................................................................10 Chapter 2: A meta-analysis of global avian survival across species and latitude ..................11 2.1 Introduction ........................................................................................................................11 2.2 Methods..............................................................................................................................14 2.2.1 Assembling a global dataset of avian survival rates ..............................................14 2.2.2 Extracting data for latitude, climate, and species’ intrinsic traits ..........................15 vii 2.2.3 Statistical analysis ..................................................................................................17 2.3 Results ................................................................................................................................19 2.3.1 Meta-analytical means ...........................................................................................19 2.3.2 Relationships between intrinsic and extrinsic moderators .....................................19 2.4 Discussion ..........................................................................................................................21 2.4.1 Global-scale patterns of avian survival with latitude .............................................21