AMNWR 2017/02 BIOLOGICAL MONITORING AT AIKTAK ISLAND, ALASKA IN 2016 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 January 2017 Cite as: Youngren, S. M., D. C. Rapp, and N. A. Rojek. 2017. Biological monitoring at Aiktak Island, Alaska in 2016. U.S. Fish and Wildl. Serv. Rep., AMNWR 2017/02. Homer, Alaska. Tufted puffins flying along the southern coast of Aiktak Island, Alaska. TABLE OF CONTENTS Page INTRODUCTION ........................................................................................................................................... 1 STUDY AREA ............................................................................................................................................... 1 METHODS .................................................................................................................................................... 2 INTERESTING OBSERVATIONS ................................................................................................................ 5 ACKNOWLEDGMENTS ................................................................................................................................ 5 REFERENCES .............................................................................................................................................. 5 ISLAND MAPS .............................................................................................................................................. 7 FIGURES AND TABLES ............................................................................................................................... 9 Black oystercatcher .............................................................................................................................. 10 Breeding chronology ...................................................................................................................... 10 Reproductive performance ............................................................................................................. 13 Populations .................................................................................................................................... 15 Food habits .................................................................................................................................... 17 Common murre ..................................................................................................................................... 19 Breeding chronology ...................................................................................................................... 19 Reproductive performance ............................................................................................................. 22 Thick-billed murre ................................................................................................................................. 26 Breeding chronology ...................................................................................................................... 26 Reproductive performance ............................................................................................................. 29 All murres .............................................................................................................................................. 33 Populations .................................................................................................................................... 33 Pigeon guillemot ................................................................................................................................... 37 Populations .................................................................................................................................... 37 Ancient murrelet.................................................................................................................................... 41 Breeding chronology ...................................................................................................................... 41 Reproductive performance ............................................................................................................. 44 Horned puffin ........................................................................................................................................ 46 Breeding chronology ...................................................................................................................... 46 Reproductive performance ............................................................................................................. 49 Chick growth .................................................................................................................................. 51 Populations .................................................................................................................................... 53 Food habits .................................................................................................................................... 58 Tufted puffin .......................................................................................................................................... 61 Breeding chronology ...................................................................................................................... 61 Reproductive performance ............................................................................................................. 64 Chick growth .................................................................................................................................. 66 Populations .................................................................................................................................... 68 Food habits .................................................................................................................................... 72 Glaucous-winged gull ........................................................................................................................... 81 Breeding chronology ...................................................................................................................... 81 Reproductive performance ............................................................................................................. 84 Populations .................................................................................................................................... 88 Food habits .................................................................................................................................... 93 i TABLE OF CONTENTS (continued) Page Fork-tailed storm-petrel ...................................................................................................................... 103 Breeding chronology .................................................................................................................... 103 Reproductive performance ........................................................................................................... 107 Chick growth ................................................................................................................................ 111 Food habits .................................................................................................................................. 113 Adult morphology ......................................................................................................................... 117 Leach’s storm-petrel ........................................................................................................................... 118 Breeding chronology .................................................................................................................... 118 Reproductive performance ........................................................................................................... 121 Chick growth ................................................................................................................................ 125 Food habits .................................................................................................................................. 127 Adult morphology ......................................................................................................................... 131 All storm-petrels .................................................................................................................................. 132 Reproductive performance ........................................................................................................... 132 Populations .................................................................................................................................