MIGRATION DYNAMICS: TESTING ECOLOGICAL ...

MIGRATION DYNAMICS: TESTING ECOLOGICAL THEORY WITH TRACKING DATA FOR AETHIA AUKLETS IN THE NORTH PACIFIC

by

© Carley Schacter

A thesis submitted to the School of Graduate Studies in partial fulfillment of the requirements for the degree of

Doctor of Philosophy

Department of Biology Memorial University of Newfoundland

Submitted May 2017

St. John’s, Newfoundland & Labrador

Abstract: Tracking technology has profoundly changed the study of spatial dynamics in marine vertebrates, enabling a large-scale focal-animal approach. This thesis shows that tracking data can be used, not only to characterize the annual migration cycle, but also to address ecological theory. I used geolocation tags (1g, 0.8-1.8% body mass) to investigate migration in a group of closely related seabirds. I found little evidence of negative effects of tags on Parakeet Auklets (Aethia psittacula), but tagged Whiskered Auklets (A. pygmaea) showed decreased chick growth, and reduced adult return rate. I combined tracking data with nest monitoring to test Ashmole’s hypothesis that seabird populations are regulated by decreases in local food availability during the breeding season. If food was limiting, individuals should leave soon after breeding is completed. I found no evidence to support resource depletion in planktivorous auklets. Whiskered Auklets remained near the colony all year, and lag times for Parakeet and Crested (A. cristatella) auklets were up to 30 days. Interspecific differences were more consistent with differences in migration strategy than food availability. I also synthesized several aspects of migratory theory into a migratory continuum on which I placed my three species (using a priori knowledge about distribution, and behaviour) to develop and test predictions about migration distance, consistency, and winter habitat. Tracking data supported my classification of Whiskered (residents), Parakeet (intermediate migrants) and Crested auklets (long distance directed migrants). Crested Auklets had longer migration distances than Parakeet Auklets, and greater consistency in most measures of winter habitat use. Whiskered Auklet residence is likely enabled by their less seasonal

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food supply, and night roosting to reduce metabolic costs. Crested Auklets’ foraging style makes them more dependent on patchy aggregations of prey, which was reflected in their concentration in highly productive areas. Parakeet Auklets spent most of the year in the deep Aleutian Basin, where their flexible diet may allow them to subsist on gelatinous zooplankton and associated amphipods. Tracking data from comparative systems like this one have great potential for addressing ecological theory, while contributing to our understanding of different ways in which seabirds have adapted to the marine environment. Acknowledgments: Financial support was provided by the Natural Sciences and Engineering Research Council of Canada (Discovery Grant to Ian L. Jones), North Pacific Research Board grants to ILJ (Project #1212, publication #640) and CRS (Graduate Student Research Award), the Northern Scientific Training Program, and the Program for Northern Mobility. Research at Buldir and Gareloi islands was conducted under US federal Master Banding Permit #22181 held by ILJ, and in compliance with the animal care regulations of Memorial University of Newfoundland, IACC (protocols 12-01-ILJ to 15-01-ILJ). I would not have been able to conduct this research without a lot of help. Chelsey Stephenson, Matt Webb, Eva Gruber, Ethan Slattery, Michelle Goh, Katy Gibb, and Lucy Smith provided invaluable assistance in the field, as did my colleagues Ian Jones, Katherine Robbins, Jill Robinson, Heather Major and Christy Wails. I am deeply indebted to the Alaska Maritime National Wildlife Refuge and its staff for believing in

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the importance of this research and providing financial, logistic, and moral support at all stages of the project. I would especially like to thank Jeff Williams, Nora Rojek, Lisa Spitler, Captain Billy Pepper, and the rest of the crew of the R/V Tiglax. Many refuge biologists and technicians helped out with field work, and generally made life in the wilderness better, including John Warzybok, Matt Henschen, Ronan Dugan, Robby Kohley, Rachael Herman, Ryan DeRegnier, Emily Pollom, John Gorey, Sara Naval, Eva Gruber, Ethan Slattery, Katy Gibb, Jenna Donaldson, Kevin Pietrzak, McKenzie Mudge, and Ryan Mong. Thanks to David Schneider, Alistair Bath and Ian Jones for shepherding me through the thesis process. Thanks also to Daniel Costa, William Montevecchi, Yolanda Wiersma, and several anonymous reviewers for helpful comments on the dissertation and the tag effects manuscript. James Fox at Migrate Technology was always available to answer questions about geolocation tag deployment and data processing. Ted Miller and David Wilson provided advice regarding the analysis and visualization of Song Meter data. Code used to analyze the data from immersion sensors on the tags was adapted from that provided by April Hedd and Paul Regular, with additional coding assistance from Kyle Krumsick. Genetic sex determination was conducted by the Genomics and Proteomics Facility at Memorial University of Newfoundland, with much assistance and advice from Brettney Pilgrim. Table of Contents

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Abstract ............................................................................................................................................ ii Acknowledgments........................................................................................................................... iii Table of Contents ............................................................................................................................ iv List of Tables ................................................................................................................................. viii List of Figures .................................................................................................................................. ix List of Abbreviations and Symbols .................................................................................................xvi List of Appendices ........................................................................................................................ xviii CHAPTER 1: INTRODUCTION AND OVERVIEW ................................................................................. 1 Co-authorship Statement .............................................................................................................. 18 CHAPTER 2: EFFECTS OF GEOLOCATION TRACKING DEVICES ON BEHAVIOUR, REPRODUCTIVE SUCCESS AND RETURN RATE OF AETHIA AUKLETS: AN EVALUATION OF TAG MASS GUIDELINES 20 Abstract ...................................................................................................................................... 21 Introduction ............................................................................................................................... 22 Methods ..................................................................................................................................... 24 Literature Review ................................................................................................................... 24 Study site................................................................................................................................ 25 Treatments ............................................................................................................................. 25 Device attachment ................................................................................................................. 26 Fledging success ..................................................................................................................... 28 Statistical analysis .................................................................................................................. 29 Results ........................................................................................................................................ 31 Literature review.................................................................................................................... 31 Auklet tracking study ............................................................................................................. 31 Discussion .................................................................................................................................. 34

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Acknowledgments...................................................................................................................... 38 Tables ......................................................................................................................................... 40 Figures ........................................................................................................................................ 42 CHAPTER 3: MIGRATORY TIMING IN COLONIAL SPECIES: IMPLICATIONS FOR POPULATION REGULATION .................................................................................................................................. 45 Abstract ...................................................................................................................................... 46 Introduction ............................................................................................................................... 47 Methods ..................................................................................................................................... 54 Study area .............................................................................................................................. 54 Device attachment and productivity monitoring .................................................................. 55 Tracking data processing........................................................................................................ 57 Analysis .................................................................................................................................. 58 Results ........................................................................................................................................ 59 Discussion .................................................................................................................................. 61 Acknowledgments...................................................................................................................... 68 Tables ......................................................................................................................................... 70 Figures ........................................................................................................................................ 71 CHAPTER 4: YEAR-ROUND RESIDENCE AT THE COLONY CONFIRMED IN A SUBARCTIC SEABIRD . 79 Abstract ...................................................................................................................................... 80 Introduction ............................................................................................................................... 81 Methods ..................................................................................................................................... 82 Study area .............................................................................................................................. 82 Device attachment ................................................................................................................. 83 Tracking data processing........................................................................................................ 83 Immersion data ...................................................................................................................... 84 Audio recordings .................................................................................................................... 85 Results ........................................................................................................................................ 86 Tracking data.......................................................................................................................... 86 Immersion data ...................................................................................................................... 86 Audio recordings .................................................................................................................... 87

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Discussion .................................................................................................................................. 87 Acknowledgments...................................................................................................................... 91 Figures ........................................................................................................................................ 93 CHAPTER 5: THE RESIDENT-MIGRANT SPECTRUM: A TEST OF PREDICTIONS WITH AETHIA AUKLETS ......................................................................................................................................... 99 Abstract .................................................................................................................................... 100 Introduction ............................................................................................................................. 102 Methods ................................................................................................................................... 112 Study site.............................................................................................................................. 112 Device attachment ............................................................................................................... 113 Tracking data processing...................................................................................................... 113 Immersion data and migration velocity ............................................................................... 116 Spatial measurements and non-breeding habitat ............................................................... 117 Aerodynamic calculations .................................................................................................... 118 Analysis ................................................................................................................................ 118 Results ...................................................................................................................................... 120 Dive depth ............................................................................................................................ 121 Description of Parakeet Auklet migration and non-breeding habitat ................................. 121 Migration distances ............................................................................................................. 123 Relative habitat use ............................................................................................................. 125 Consistency of space use ..................................................................................................... 126 Immersion data and migration velocity ............................................................................... 127 Aerodynamic calculations .................................................................................................... 128 Discussion ................................................................................................................................ 129 Acknowledgments.................................................................................................................... 144 Tables ....................................................................................................................................... 146 Figures ...................................................................................................................................... 150 CHAPTER 6: SYNTHESIS ................................................................................................................ 165 LITERATURE CITED ....................................................................................................................... 186

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APPENDICES ................................................................................................................................. 229

List of Tables: Table 2-1. Parakeet and Whiskered Auklet samples sizes for each experimental treatment per year...............................................................................................................................40 Table 2-2. Summary of studies included in review of tag effects, broken down by taxonomy, size of species studied, and percent body mass of tag used. Only studies that provided the relevant information were included, so totals may differ. ............................41 Table 3-1. Number of tags recovered (for each species, island, and year) and the number of birds for which each type of data could be determined. ................................................70 Table 5-1. Measurements of auklet carcasses salvaged on Buldir Island 2012-2014, with aerodynamic calculations (following Pennycuick 1989) and data from Spear & Ainley (1997) for comparison. Note: I did not measure mass for partially consumed carcasses. ..........................................................................................................................147 Table 5-2. Sample sizes of Intigeo C-65 tags recovered with data (for each species, island, and year). ..............................................................................................................148 Table 5-3. Summary of statistical results showing differences in relative habitat use (percent of volume contour (VC) overlapping each bathymetry zone) of Parakeet and Crested auklets for different bathymetry zones over time. Significance presented after tvalues (*** p