• Declines in Aleutian and Arctic tern numbers were highest at large colonies on the southeastern end of Kodiak Island.

• Intra-annual variability in counts was high most likely as a result of high nest failure, variable rates of re-nesting, and colony abandonment.

• Tern monitoring efforts on Kodiak highlight the difficulty that intra-annual variability in colony occupancy and size has on determining population trends.

Status of Aleutian and Arctic Terns breeding in the Kodiak Archipelago, Alaska, 2016-2017

Introduction Aleutian terns (Onychoprion aleutica) are colonial nesting seabirds that breed in coastal Alaska and the Russian far east, often in association with Arctic terns (Sterna paradisaea). Recent trend analysis of numbers of Aleutian terns at colonies in Alaska indicates that this poorly known seabird has declined by almost 93% over the past three decades. The much more abundant and widely distributed Arctic tern also appears to have declined by more than 90% regionally in coastal locations in the Gulf of Alaska (GOA). However, there is a high degree of uncertainty in breeding population status of both species due to their scattered and remote nesting locations, and variable site fidelity and colony attendance patterns. Tern colonies in the Kodiak Archipelago have been the focus of monitoring and research periodically since the 1970s, providing valuable information on the status and ecology of both species in the GOA.

Goal 1: Count terns at known colonies, search for new nesting locations, and compare results to previous surveys

Conclusions

Acknowledgements We sincerely thank the seasonal avian monitoring interns who volunteered on surveys including Amee Van Tatenhove, SJ Kwiatowski, Eva Kwiatek, and KNWR biological technicians Tim Knudson and Katie Stoner. We thank the staff of the Kodiak NWR for help with logistics, in particular Jeff Lewis, Captain of the Refuge research boat the Ursa Major II. We thank Rich MacIntosh for help with surveys and generously sharing many years of survey data.

Robin M. Corcoran1 (robin_corcoran@ fws.gov), Jill E. Tengeres2, and Donald E. Lyons2

1U.S. Fish and Wildlife Service, Kodiak National Wildlife Refuge, 1390 Buskin River Rd., Kodiak, AK; 2Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis, OR.

• During the 2017 breeding season we surveyed for terns at 44 of the 53 known breeding sites in the archipelago. • Aleutian terns were active at 11 colonies (nesting was confirmed at 5) and colony size varied from 1 to 212 individuals. • Arctic terns were observed at 28 colonies (nesting was confirmed at 11) and colony size varied from 4 to 150 individuals. • Declines between decades were most evident at previously large colonies on the southeastern end of Kodiak Island .

Intra-annual Variability • Coefficient of Variation (CV) on counts

varied from 0.15 – 2.77 for Aleutian terns (ALTE) and 0.39 to 1.76 for Arctic terns(ARTE).

Goal 2: Document variability in colony counts to inform state-wide monitoring plans

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Coefficient of Variation (June 1 – August 1)

Aleutian Tern Arctic Tern

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0.39 (n = 5 counts)

0.32 (n = 10 counts)

1.37 (n=4 counts)

1.76 (n=10 counts)

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2.77 (n = 12 counts)

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1.45 (n=12 counts)

• Counts from early June to mid-July capture peak nesting.

• The largest Aleutian tern colony in the Kodiak Archipelago at the Pasagshak River has completely abandoned in early June for the past two breeding seasons.

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Bald Eagle attack on 9 June 2016 resulted in all terns abandoning

Multiple predators & a severe storm on 6-7 June 2017 resulted in all terns

abandoning