AMNWR 2019/02 BIOLOGICAL MONITORING AT AIKTAK ISLAND, ALASKA IN 2018 Sarah M. Youngren, Daniel C. Rapp, and Nora A. Rojek Key words: Aiktak Island, Alaska, Aleutian Islands, ancient murrelet, Cepphus columba, common murre, double-crested cormorant, fork-tailed storm-petrel, Fratercula cirrhata, Fratercula corniculata, glaucous-winged gull, horned puffin, Larus glaucescens, Leach’s storm-petrel, Oceanodroma furcata, Oceanodroma leucorhoa, pelagic cormorant, Phalacrocorax auritus, Phalacrocorax pelagicus, Phalacrocorax urile, pigeon guillemot, population trends, productivity, red-faced cormorant, Synthliboramphus antiquus, thick-billed murre, tufted puffin, Uria aalge, Uria lomvia. U.S. Fish and Wildlife Service Alaska Maritime National Wildlife Refuge 95 Sterling Highway, Suite 1 Homer, AK 99603 March 2019 Cite as: Youngren, S. M., D. C. Rapp, and N. A. Rojek. 2019. Biological monitoring at Aiktak Island, Alaska in 2018. U.S. Fish and Wildl. Serv. Rep., AMNWR 2019/02. Homer, Alaska. Tufted puffins swirl on the south side of Aiktak island. TABLE OF CONTENTS Page INTRODUCTION ........................................................................................................................................... 1 STUDY AREA ............................................................................................................................................... 1 METHODS .................................................................................................................................................... 2 INTERESTING OBSERVATIONS ................................................................................................................ 6 ACKNOWLEDGMENTS ................................................................................................................................ 7 REFERENCES .............................................................................................................................................. 7 ISLAND MAPS .............................................................................................................................................. 9 FIGURES AND TABLES ............................................................................................................................. 11 Black oystercatcher .............................................................................................................................. 12 Breeding chronology ...................................................................................................................... 12 Reproductive performance ............................................................................................................. 15 Populations .................................................................................................................................... 17 Food habits .................................................................................................................................... 19 Common murre ..................................................................................................................................... 21 Breeding chronology ...................................................................................................................... 21 Reproductive performance ............................................................................................................. 24 Thick-billed murre ................................................................................................................................. 28 Breeding chronology ...................................................................................................................... 28 Reproductive performance ............................................................................................................. 31 All murres .............................................................................................................................................. 35 Populations .................................................................................................................................... 35 Pigeon guillemot ................................................................................................................................... 39 Populations .................................................................................................................................... 39 Ancient murrelet.................................................................................................................................... 43 Breeding chronology ...................................................................................................................... 43 Reproductive performance ............................................................................................................. 46 Horned puffin ........................................................................................................................................ 49 Breeding chronology ...................................................................................................................... 49 Reproductive performance ............................................................................................................. 52 Chick growth .................................................................................................................................. 54 Populations .................................................................................................................................... 56 Food habits .................................................................................................................................... 61 Tufted puffin .......................................................................................................................................... 64 Breeding chronology ...................................................................................................................... 64 Reproductive performance ............................................................................................................. 67 Chick growth .................................................................................................................................. 69 Populations .................................................................................................................................... 71 Food habits .................................................................................................................................... 75 Glaucous-winged gull ........................................................................................................................... 84 Breeding chronology ...................................................................................................................... 84 Reproductive performance ............................................................................................................. 87 Populations .................................................................................................................................... 91 Food habits .................................................................................................................................... 97 i TABLE OF CONTENTS (continued) Page Fork-tailed storm-petrel ...................................................................................................................... 108 Breeding chronology .................................................................................................................... 108 Reproductive performance ........................................................................................................... 112 Chick growth ................................................................................................................................ 116 Food habits .................................................................................................................................. 118 Adult morphology ......................................................................................................................... 124 Leach’s storm-petrel ........................................................................................................................... 125 Breeding chronology .................................................................................................................... 125 Reproductive performance ........................................................................................................... 128 Chick growth ................................................................................................................................ 132 Food habits .................................................................................................................................. 134 Adult morphology ......................................................................................................................... 138 All storm-petrels .................................................................................................................................. 139 Reproductive performance ........................................................................................................... 139 Populations .................................................................................................................................. 143