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Planktivorous Auklets (Aethia Pusilla and A. Cristatella) Nesting on St

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Planktivorous Auklets (Aethia Pusilla and A. Cristatella) Nesting on St AN ABSTRACT OF THE THESIS OF Adrian E. Gall for the degree of Master of Science in Wildlife Science presentedon March 22. 2004. Title: Planktivorous Aukiets (Aethia cristatella and A. Dusilla) Nestingon St. Lawrence Island. Alaska as Indicators of Marine Conditions in the Northern Bering Sea. Abstract approved: Redacted for Privacy Daniel D. Roby Monitoring reproductive success, prey species composition, and colony size of marine birds has been proposed as a method of assessing changes in marine systems that are otherwise difficult to sample (Cairns 1987).I measured inter- annual and intra-seasonal variability in reproductive parameters, taxonomic composition of the diet, and adult body condition of Crested Aukiets (Aethia cristatella) and Least Auklets (A. pusilla) at 2 colonies near the village of Savoonga, St. Lawrence Island, Alaska during the 2000-2002 breeding seasons to evaluate how reproductive success of planktivorous seabirds is related to diet.I also assessed the utility of two methods of population monitoring (surface counts and mark-resighting) for detecting annual changes in breeding populations of Crested and Least auklets during the 2001 and 2002 breeding seasons on the Kitnik colony. Average reproductive success was generally high (>60% of nests) for both auklet species during the 3 years of the study, but differed amongyears. Median hatching dates for both species were 2 weeks earlier in the year of highest reproductive success (2002), compared to the previous 2 years. In all 3years, the diet of Crested Auklets was predominantly euphausiids, while the diet of Least Aukiets consisted primarily of calanoid copepods, but species composition of thediet differed among years for both species. Crested and Least auklets consumedmore of the large, lipid-rich copepod Neocalanus cristatus in 2002 than in the other 2years of the study. The year of lowest reproductive success (2001) was associated with low prevalence of euphausiids in Crested Auklet diets late in the chick-rearing period and high prevalence of the small, low-lipid copepod Ca/anus marshal/ae in Least Auklet diets. I observed an increase in total body mass of Crested Auklets during the 2002 breeding season, whereas total body mass declined through the breedingseason in the other 2 years. Seasonal changes in adult body mass of Crested Aukletsmay, therefore, be a useful indicator of food availability. Average body mass of Least Auklets declined in all 3 years, but was lowest in 2001, suggesting that low adult body mass of Least Auklets may reflect poor foraging conditions. Fat reserves of breeding aukiets during egg-laying were not highly variable among or within breeding seasons and therefore were not a sensitive predictor of subsequent breeding success. Counts of Crested Auklets in plots on the colony surface were highest inareas of large average boulder size; Least Auklet surface counts were not as variable among plots. Maximum counts of both species of aukiets in plots did not differ between years. Patterns of colony surface attendance during the breeding season, however, did differ between years. The colony surface attendance of both auklet species after hatching was higher in the year of high reproductive success. Preventing nest initiation by covering plots with tarps did not reduce subsequent colony surface attendance during chick-rearing (after the tarps were removed) for either species, suggesting that reproductive success, independent of differences in food availability, did not cause a difference in colony surface attendance.I estimated abundance of Least Auklets nesting in two100-rn2plots using mark-resight methods. I concluded that surface counts may provide an indication of among-year differences in colony attendance, but underestimate the number of breeding individuals bya factor of 10. Mark-resighting techniques show more promise for detecting changes in the number of breeding pairs. Reproductive success, adult body mass, and post- hatch colony attendance of Crested and Least auklets appear positively associated with zooplankton availability, particularly the prevalence of N. cristatus in the diet. Annual monitoring of these 3 parameters, together with diet composition, are important for understanding how both natural and anthropogenic climate change may affect trophic structure of the northern Bering Sea ecosystem. ©Copyright by Adrian Gall March 22, 2004 All Rights Reserved Planktivorous Auklets (Aethia pusilla and A. cristatella) Nestingon St. Lawrence Island, Alaska as Indicators of Marine Conditions in the NorthernBering Sea by Adrian Gall A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science Presented March 22, 2004 Commencement June 2004 Master of Science thesis of Adrian Gall presented on March 22, 2004. APPROVED: Redacted for Privacy Major Professor, representing Wildlife Redacted for Privacy Head of the Department of Redacted for Privacy D I understand that my thesis will become part of the permanent collection of Oregon State University libraries. My signature below authorizes release of my thesis to any reader upon request. Redacted for Privacy Adrian E. Gall, author ACKNOWLEDGEM ENTS First and foremost, I would like to thank Dr. Daniel D. Roby for his guidance, advice, and excitement about science in general and auklets in particular. His efforts in the field and in the office are an inspiration. My committee members Dr. Charles Miller and Dr. Robert Anthony not only provided valuable advice on my thesis, but also taught challenging and valuable courses.I thank my boss, Dr. David B. Irons, of the Division of Migratory Bird Management, U. S. Fish and Wildlife Service (MBM- USFWS) Anchorage for funding this project and offering me the amazing opportunity to work on Little Diornede, I mean, St. Lawrence Island.I also appreciate Oregon Sea Grant for supporting me with a Natural Resources Fellowship. I am indebted to the Savoonga and Gambell Native Corporations for granting me permission to study auklets on their colonies and travel around St. Lawrence Island to conduct my research. Specifically, I would like to thank Morris Toolie, Carl Pelowook, and Hogarth Kingeekuk of Savoonga and Melvin Appasingok of Gambell for their assistance with land crossing permits. Roland Alowa, Julius Alowa, Christine Alowa, Clarence Waghiyi, and Winnie James provided housing for project personnel and storage for piles of gear and machines. Calvin Akeya was invaluable for his assistance with ATV repair, maintenance and Yup'ik lessons. Denny Akeya, Tim Alowa, Sharon Alowa, Emily Pelowook, Jutian Seppilu, Harriet Penayah, and many other island residents shared their knowledge and experiences with seabirds and many good conversations for which I am grateful. Lisa DeMatteo, Arthur Gologergen, George Kava, Brian Milakovic, Mark Miklahook, Darren Noongwook, Lisa Sheffield, and Brandon Waghiyi provided tireless and round-the-sunny-clock assistance in the field.I especially appreciate Victor Zubakin of the Russian Academy of Sciences for being a wonderful mentor and providing tutelage in the art of auklet study.I thank Kathy Turco, of Alaska Spirit Speaks: Sound and Science, for doing a wonderful job sorting many zoop samples and to Ken Coyle (Institute of Marine Science, University of Alaska, Fairbanks) for verifying Kath's work and sharing his data on zooplankton of the northern Bering Sea. I am grateful to Dennis Hermannes, Kevin McClure, Vivian Powell, Burt Pratt, Margy Sinnott, Jonathan Snyder, and Shawn Stephensen of USFWS and Ellen Holsberry and Jane Toliver of Oregon State University for their logistic support and care packages. Dr. Fred Ramsey gave generously of his time and statistical knowhow. I give many thanks to the Roby Lab: Don Lyons, Sadie Wright, Scott Anderson, Patrick G.R. Jodice, Cindy Anderson, Michelle Antolos, S. Kim Nelson, Anne Mary Myers, Can Cardoni, Nate Cheigren, and Ian Rose for their camaraderie and brilliant conversation.I especially thank Daniel Rizzolo for his patience, encouragement, and passion for life. You are gold to me, D. Thanks also to my fellow graduate students and Corvallis crew, particularly: Jeff Snyder, Molly McAllister, Kate Haley, Anna Noson, John Seigle, Derek Risso, Jen Britt, Chris Krenz, Joy Tamayose, Aimee McIntyre, Kim Klein, Cortnie Krissman, Ellie Mather, and Cassie Bouska for daily amusement and susceptibility to lunchtime, coffee-time, and cookie-time excursions.I sincerely appreciate Paul and Violet Trosper for all their care and apple cake. Finally and most importantly, I would like to thank my parents, Pine and Maria Consuelo Gall for their faith, love, friendship, and constant support.I thank Daniel Catlin for his love, company, and healthy doses of honesty. To lnuksunuq, thank you for comfort and companionship every step of the way. CONTRIBUTION OF AUTHORS Dr. Daniel D. Roby was involved in the design and analysis of thisresearch and provided extensive edits of all chapters. Dr. David B. Irons provided fundingand input into the design of this study presented in Chapters 2, 3, and 4. TABLE OF CONTENTS Eg CHAPTER 1: General Introduction..................................................................................... I LITERATURECITED........................................................................................................ 6 CHAPTER 2: Interannual variation in diet, reproductivesuccess, and body mass of plankton-feeding auklets on St. Lawrence Island, Alaska..............................................
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