University of Nevada, Reno Population Ecology and Summer Habitat Selection of Mule Deer in the White Mountains: Implications of Changing Landscapes and Variable Climate A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Ecology, Evolution, and Conservation Biology by Sabrina Morano Dr. Kelley M. Stewart /Dissertation Advisor December, 2016 Copyright by Sabrina Morano 2016 All Rights Reserved THE GRADUATE SCHOOL We recommend that the dissertation prepared under our supervision by SABRINA MORANO entitled Population Ecology and Summer Habitat Selection of Mule Deer in the White Mountains: Implications of Changing Landscapes and Variable Climate be accepted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Kelley M. Stewart, Ph.D., Advisor Vernon C. Bleich, Ph.D., Committee Member James S. Sedinger, Ph.D., Committee Member Peter J. Weisberg, Ph.D., Committee Member Michael P. Branch, Ph.D., Graduate School Representative David W. Zeh, Ph. D., Dean, Graduate School December, 2016 i ABSTRACT Changes in landscape composition have the potential to negatively influence animal populations through shifts in dominant plant communities, loss of important forage items, or changes in structural components of habitat. In the western United States, expansion of woodland vegetation into shrub dominated communities is of concern, particularly with regard to animal populations reliant on robust sagebrush and shrub vegetation. Once established, trees can out-compete shrubs and herbaceous plants resulting in declines in abundance and diversity of shrub-forb vegetation, which female mule deer are reliant on during summer months to meet nutritional demands and to provide hiding cover for young. As a result, shifts in the distribution of pinyon-juniper woodland and increases in tree densities could negatively affect mule deer population. The study had two primary objectives, (1) to determine summer habitat composition of female mule deer in the White Mountains of California and eastern Nevada, and assess implications of pinyon-juniper expansion on habitat availability, and (2) evaluate the status of the population relative to nutritional carrying capacity and determined the influence of habitat and precipitation on demographic rates. I used mixed-effects logistic regression to model summer resource selection and demographic rates of female mule deer from 2005 to 2008. Summer resource selection was modeled at two spatial scales and among three behavioral periods, related to foraging, resting, and parturition. Summer habitat consisted of sites with high productivity, greater shrub abundance, and greater proximity to riparian areas. Deer avoided high levels of tree cover at all spatial and temporal scales, but they selected areas ii with low to intermediate tree cover during resting periods and during parturition. Moreover, mule deer avoided areas of productive shrub-forb vegetation (riparian and shrub NDVI), when surrounded by stands of high level pinyon-juniper cover, otherwise those vegetation types were strongly selected. During parturition female mule deer selected habitat that maximized hiding cover for newborns (greater shrub densities and structural cover), while still providing foraging opportunities (greater NDVI and shrub cover). Females underutilized certain areas that contained optimal forage such as riparian corridors, high AET sites, higher elevation shrub communities, and selected areas with low to moderate tree cover, suggesting some trade-off between minimizing predation risk for offspring, and maximizing foraging opportunities. Demographic rates (body condition, survival, fetal rates, and index of recruitment) of female mule deer were sensitive to changes in resource availability resulting from variation in precipitation or habitat composition and suggestive of a population regulated to a greater degree by bottom-up processes, and likely nearing nutritional carrying capacity. Moreover, I identified a strong negative effect of pinyon- juniper cover on annual survival, only during periods of drought, otherwise individuals were able to maintain relatively high survival regardless of habitat composition. These results suggest that in productive years mule deer are able to inhabit areas of varying levels of pinyon-juniper cover with little effect on survival, and only during the drought years are negative effects evident. Results from this study emphasize the importance of productive shrub and forb vegetation to mule deer inhabiting semi-arid regions. Maintaining areas with low-to- iii intermediate tree cover, where there is still abundant shrub understory and sufficient concealment cover, may be beneficial to mule deer populations. Nevertheless, the strong influence of resource availability on the population suggests that conversion of sagebrush-steppe communities into large stands of PJ dominated woodlands would likely reduce the quality and abundance of available habitat for mule deer in the Great Basin. iv ACKNOWLEDGEMENTS Funding for this project was provided by the Deer Management Program of the California Department of Fish and Wildlife, and the California Deer Association. Further support for this project was provided by CDFW, and the Large Mammal Advisory Committee, in addition to the Department of Natural Resources and Environmental Science, and the Ecology, Evolution and Conservation Biology Program at the University of Nevada Reno. Travel funding was provided by the UNR Graduate School and The Wildlife Society, to attend conferences, and present research. There are many people I would like to thank who assisted me with this research and the completion of my dissertation. First, my advisor Kelley Stewart for all her guidance and continued support while I completed my degree. I greatly appreciate her mentorship and the learning and networking opportunities she provided for myself and her other students. I also thank my committee members Vern Bleich, Michael Branch, Jim Sedinger and Peter Weisberg for their assistance and feedback. Especially Vern Bleich for putting me in contact with CDFW and my adviser at UNR. I would also like to thank Tom Dilts for his help with the vegetation modeling and GIS analysis. This research would not have been possible without the support of the California Department of Fish and Wildlife. Particularly my supervisor Alisa Ellsworth, who provided me the opportunity to work and live in the eastern Sierras, and taught me the ins and outs of being a field biologist. Also our technicians Brook Haverstock and Joy Erlenbach, whose positive attitudes made the arduous field work that much more enjoyable. I am also very thankful for the assistance of many employees at CDFW who helped with animal v captures, aerial surveys, and data management – Dave German, Lora Konde, Art Lawrence, Jane McKeever, Becky Pierce, Tom Stephenson, and Tim Taylor – and others. Additional capture support was provided by personnel from the CDFW Wildlife Investigations Lab. We thank Steve and Dee Dee DeJesus and the crew at Landells Aviation in addition to CDFW personnel including T. Glenner and R.Teagle for capture work, and pilots T. Evans, and G. Schales of CDFW, and G. Pope (Black Mountain Air Service) for fixed-wing support. Finally thanks to all the dedicated biologists and staff in the Bishop office, and the many friends I made while living there, I had a wonderful experience living and working in the eastern Sierras. I also feel very grateful to have had such an amazing cohort of students and faculty at the University of Nevada (of which there are too many to list), which made my time here so enjoyable. I appreciate the collegial atmosphere and feel very lucky to have had that experience. In particular I thank the members of the Sedinger Lab, and the Stewart Lab - Alyson Andreasen, Marcus Blume, Bri Boan, Tony Bush, Cynthia Downs, Cody McKee, Cody Schroeder, Nova Simpson, Ben Sedinger, and Danielle Walsh - for all their assistance and feedback. I thank my parents for their continuous encouragement, and giving me the confidence and opportunity to follow my passions. I would not have made it this far without their support. Also my friends and family, especially Pauline Morano for her enthusiasm and inspiration. Finally I would like to thank Erik Blomberg, for being my rock and my best friend, and helping me stay focused and have fun along the way. vi TABLE OF CONTENTS Abstract ............................................................................................................................... i Acknowledgements ........................................................................................................... iv Table of Contents .............................................................................................................. vi List of Tables .................................................................................................................. viii List of Figures .................................................................................................................. xii Introduction ........................................................................................................................ 1 Literature Cited .................................................................................................................. 9 Chapter 1. Woodland encroachment in a shrub-steppe ecosystem: effects on resource availability and behavior of a native ungulate ................................................................