The Ross's Gull (Rhodostethia rosea) in North America by © Mark Maftei A Thesis submitted to the School of Graduate Studies in partial fulfillment of the requirements for the degree of Master of Science Department of Biology Memorial University of Newfoundland May, 2014 St. John’s Newfoundland and Labrador Plate 1 An adult Ross's gull - one of the rarest and least studied seabirds in the world i ABSTRACT The population, distribution and range of the Ross's gull in North America remain poorly understood, as does almost every aspect of its ecology and biology. It breeds at a few disparate locations in the Canadian Arctic and is an annual fall migrant in northern Alaska where tens of thousands occur in the nearshore waters of the Beaufort and Chukchi Seas, but little else is known about the distribution, habitat requirements, migratory routes and wintering areas used by this species. In order to clarify the status of the Ross's gull in North America I sought to discover new breeding sites in the Canadian High Arctic in order to characterize nesting habitat requirements, develop a predictive model with which to identify suitable nesting habitat for Ross's gulls, and refresh outdated estimates of the number of individuals migrating past Point Barrow, Alaska. Taken together, my findings provide a comprehensive account of the current status of the Ross's gull in North America. ii ACKNOWLEDGEMENTS I would like to thank Dr. Mark Mallory for first introducing me to the remarkable world of the Ross's gull, and subsequently granting me the opportunity to carry out this research and supporting both me and my work in every possible way. I also thank Dr. Edward Miller and Dr. Gregory Robertson for their helpful advice and guidance along the way, and I am especially grateful for their generous assistance in matters relating to statistical analysis and display behaviour respectively. Finally, I wish to thank Shanti Davis for her assistance in the field, in the lab, and throughout the process of preparing this thesis. iii Table of Contents ABSTRACT ........................................................................................................................ ii ACKNOWLEDGEMENTS ............................................................................................... iii Table of Contents ............................................................................................................... iv List of Tables ..................................................................................................................... vi List of Figures ................................................................................................................... vii List of Plates .................................................................................................................... viii GENERAL INTRODUCTION ........................................................................................... 1 Justification of Research .............................................................................................................. 1 Historical records ......................................................................................................................... 2 Taxonomy and phylogeny ............................................................................................................ 4 Breeding range and distribution ................................................................................................... 7 Wintering areas ............................................................................................................................ 8 Migratory movements ................................................................................................................ 10 Breeding biology ........................................................................................................................ 11 Conservation status .................................................................................................................... 14 Research objectives .................................................................................................................... 15 Literature cited ........................................................................................................................... 17 BREEDING HABITAT AND NEW BREEDING LOCATIONS FOR ROSS'S GULL (Rhodostethia rosea) IN THE CANADIAN HIGH ARCTIC .......................................... 21 Abstract ...................................................................................................................................... 21 Introduction ............................................................................................................................... 22 Methods ..................................................................................................................................... 23 Results ....................................................................................................................................... 24 Discussion .................................................................................................................................. 25 Acknowledgements ................................................................................................................... 29 References ................................................................................................................................. 29 iv ASSESSING REGIONAL POPULATIONS OF GROUND-NESTING SEABIRDS IN THE CANADIAN HIGH ARCTIC .................................................................................. 35 Abstract ...................................................................................................................................... 35 Introduction ............................................................................................................................... 36 Methods ..................................................................................................................................... 37 Results ....................................................................................................................................... 41 Discussion .................................................................................................................................. 43 Acknowledgements ................................................................................................................... 47 References ................................................................................................................................. 47 Appendix 1. Metadata for ArcGIS raster layers ........................................................................ 58 Appendix 2. Additional Methods for ArcGIS Analysis ............................................................ 58 QUANTIFYING FALL MIGRATION OF ROSS'S GULLS PAST POINT BARROW, ALASKA .......................................................................................................................... 60 Abstract ...................................................................................................................................... 60 Introduction ............................................................................................................................... 61 Materials and Methods .............................................................................................................. 62 Results ....................................................................................................................................... 63 Discussion .................................................................................................................................. 65 Acknowledgements ................................................................................................................... 70 References ................................................................................................................................. 70 GENERAL DISCUSSION ............................................................................................... 76 Breeding range and distribution ................................................................................................. 79 Wintering range ......................................................................................................................... 80 Migratory movements ................................................................................................................ 81 Breeding in Canada .................................................................................................................... 82 Conclusion ................................................................................................................................. 84 Literature cited ........................................................................................................................... 84 v List of Tables Table 1-1 Summary of Ross's gull breeding records in the Nearctic ................................. 32 Table 2-1 Observed numbers of birds on islands in Queens Channel in 2002 and 2012 .. 54 Table 2-2 Annual maximum and mean numbers of commonly observed species on Nasaruvaalik Island, NU, from 2007 to 2012. ................................................................... 56 Table 3-1 Multi-year comparison of Ross's gull migration past Point Barrow ................. 75 vi List of Figures