Seabird Colony Survey of South and East Kodiak Island, Alaska, June 2001
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SEABIRD COLONY SURVEY OF SOUTH AND EAST KODIAK ISLAND, ALASKA, JUNE 2001 Shawn W. Stephensen, Dennis C. Zwiefelhofer, and Rebecca J. Howard Key words: Alaska, Aleutian tern, arctic tern, Beringian Seabird Colony Catalog, black-legged kittiwake, breeding population, census, double-crested cormorant, Kodiak Island, pelagic cormorant, pigeon guillemot, red-faced cormorant, seabird colony, survey U.S. Fish and Wildlife Service Migratory Bird Management 1011 East Tudor Road Anchorage, Alaska 99503-6199 April 2002 Cite as: Stephensen, S.W., D.C. Zwiefelhofer, and R.J. Howard. 2002. Seabird Colony Survey of South and East Kodiak Island, Alaska, June 2001. U.S. Fish and Wildlife Service Report. Migratory Bird Management Anchorage, Alaska. 23 pp. SEABIRD COLONY SURVEY OF SOUTH AND EAST KODIAK ISLAND, ALASKA, JUNE 2001 Shawn W. Stephensen, Dennis C. Zwiefelhofer, and Rebecca J. Howard Key words: Alaska, Aleutian tern, arctic tern, Beringian Seabird Colony Catalog, black-legged kittiwake, breeding population, census, double-crested cormorant, Kodiak Island, pelagic cormorant, pigeon guillemot, red-faced cormorant, seabird colony, survey U.S. Fish and Wildlife Service Migratory Bird Management 1011 East Tudor Road Anchorage, Alaska 99503-6199 April 2002 ___ Cite as: Stephensen, S.W., D.C. Zwiefelhofer, and R.J. Howard. 2002. Seabird Colony Survey of South and East Kodiak Island, Alaska, June 2001. U.S. Fish and Wildlife Service Report. Migratory Bird Management Anchorage, Alaska. 23 pp. TABLE OF CONTENTS Page ABSTRACT .................................................................................................................................................. i INTRODUCTION ......................................................................................................................................... 1 METHODS .................................................................................................................................................... 2 Expedition Log ................................................................................................................................. 3 RESULTS ...................................................................................................................................................... 4 DISCUSSION ................................................................................................................................................ 5 ACKNOWLEDGMENTS ............................................................................................................................. 6 LITERATURE CITED .................................................................................................................................. 7 LIST OF FIGURES Figure Page 1 Seabird colonies censused on the south and east side of Kodiak Island, Alaska during June 2001 .......................................................................................................................................... 8 LIST OF TABLES Table Page 1 Present and historical arctic and Aleutian tern counts (individual birds) at colonies on the south and east side of Kodiak Island, Alaska ............................................................................................. 9 2 Present and historical red-faced, pelagic, and double-crested cormorant counts (individual birds may be derived from nest counts) at colonies on the south and east side of Kodiak Island, Alaska ................................................................................................................................... 11 3 Present and historical pigeon guillemot counts (individual birds) at colonies on the south and east side of Kodiak Island, Alaska ................................................................................................... 13 4 Count of nests or individual breeding birds at colonies on the south and east side of Kodiak Island, Alaska during June 2001 ...................................................................................................... 17 5 Common and scientific names of bird and marine mammal species observed on the south and east side of Kodiak Island, Alaska during June 2001 ....................................................................... 21 6 Count of sea otters, Steller sea lions, and harbor seals near seabird colonies on the south and east side of Kodiak Island, Alaska during June 2001 ....................................................................... 22 7 Location and counts of waterfowl and shorebird species on the south and east side of Kodiak Island, Alaska during June 2001 ...................................................................................................... 23 SEABIRD COLONY SURVEY OF SOUTH AND EAST KODIAK ISLAND, ALASKA, JUNE 2001 ABSTRACT Migratory Bird Management, Kodiak National Wildlife Refuge, and Alaska Maritime National Wildlife Refuge personnel cooperatively conducted a seabird colony survey of the south and east side of Kodiak Island, Alaska during June 2001. The purpose of the survey was to aid in determining if breeding populations of cormorants, terns, and pigeon guillemot are declining at portions of Kodiak Island. In addition, all other known diurnal colonial nesting seabirds were censused in the study area. We surveyed 165 km of shoreline by boat and 166 km2 of island area by plane and recorded approximately 51,400 birds and 850 marine mammals. A total of 70 seabird colonies were censused. Cormorants and terns have declined in the study area compared to historical estimates. Eight previously documented cormorant colonies were inactive and 6 new colonies were observed. Only 3 of the 14 historically documented tern colonies were active and no new colonies were discovered. Pigeon guillemot breeding population numbers are comparable to previous censuses. The seabird colony data collected during this survey will be stored in the Beringian Seabird Colony Catalog database. INTRODUCTION The U.S. Fish and Wildlife Service (USFWS) utilizes seabird distribution and abundance data to aid in seabird conservation. The Beringian Seabird Colony Catalog (Catalog) computer database, maintained by Migratory Bird Management (MBM), stores current and historical seabird colony data on breeding population size, species composition, and location data of Alaska and Russia Far East (USFWS 2002). Seabird colony data are gathered, stored, and made available whenever needed. Seabird colony surveys are conducted to replace old or low quality data and to maintain the reliability of the Catalog (Stephensen and Mendenhall 1998). Kodiak National Wildlife Refuge (KNWR) personnel conduct annual near shore surveys of seabirds and marine mammals during February, May, and August at selected areas of Kodiak Island. The surveys conducted in May and August provide distribution and abundance data needed to determine species aggregations and possible seabird colony locations. Breeding populations of cormorants (red-faced, pelagic, and double-crested), terns (arctic and Aleutian), and pigeon guillemot may be declining in Alaska. To date, little data are available to assess population trends of terns and guillemots. Generally, colonies that are monitored annually or intermittently are used to assess trends, but currently USFWS monitors few tern and pigeon guillemot colonies. Cormorants populations at colonies are monitored by USFWS throughout Alaska (Dragoo et al. 2000). Historically, large colonies of cormorants, terns, and pigeon guillemot were observed on and around Kodiak Island (U.S. Fish and Wildlife Service 2002). MBM in cooperation with KNWR and Alaska Maritime National Wildlife Refuge (AMNWR) initiated a survey of seabird colonies on the south and east side of Kodiak Island in June 2001. The primary objective of the survey was to census arctic and Aleutian tern colonies. The secondary objective was to census cormorant and pigeon guillemot colonies, and the tertiary objective was to census all other diurnal colonial seabirds nesting along the east shore of Kodiak Island. The data will be used to update the Beringian Seabird Colony Catalog with new colony data and aid in determining if cormorants, terns, and pigeon guillemots are declining. In this report, we compare present and historical cormorant, tern, and pigeon guillemot colony ii data. Breeding population estimates of all other colonial nesting species are included for sites where data were gathered during this survey. METHODS Kodiak Island is located in the Gulf of Alaska, 50 km east of the Alaska Peninsula and 140 km southwest of the Kenai Peninsula. The study area included portions of shoreline and adjacent islands on the east and south side of Kodiak Island (Figure 1). The survey crew included KNWR biologist/ship operator Dennis C. Zwiefelhofer, MBM biologist Shawn W. Stephensen, and AMNWR biological technician Rebecca J. Howard. The 48 ft vessel Ursa Major II and 16 ft aluminum skiff were provided by KNWR. The Ursa Major II, piloted by Zwiefelhofer, was the support vessel and the skiff was used while conducting the shoreline surveys. Throughout the survey, we focused on shoreline areas with potential seabird breeding habitat and where birds were noted previously during KNWR May and August coastal surveys. Surveys were generally conducted in the morning and early afternoon, to avoid strong day breezes that commonly developed in the afternoon. We traveled in the 16 ft skiff 20-100 meters offshore and counted the number of birds or nests by 1's with the aid of binoculars. Also,