Introduced mammals often reduce bird abundance and diversity, especially on islands. The Sanak Islands, within Alaska’s Aleutian Islands, are on the migratory pathway for many birds. Sanak Island previously had nesting seabird colonies, but after recent Arctic fox introduction, no seabirds currently nest on Sanak. Indigenous Aleut people lived on Sanak for 6,000 years consuming birds and eggs, and red foxes were present at least 2,550 years before present. Native red foxes likely affected bird communities in the past. To examine this we analyzed bird and fox bones from prehistoric village refuse deposits (middens) and explore the impacts of foxes on bird community composition and abundance relative to other midden remains. The USFWS has been eradicating introduced Arctic foxes since 1949, but the impacts on bird communities have rarely been quantitatively documented. The impacts of a similar predator, the native red fox, on bird assemblages may provide insights about bird response to Arctic fox eradication. A preserved red fox den dated to approximately 1760 A.D. contained food remains that suggest what birds were living on Sanak. Of the 15 bird taxa (mainly seabirds) represented in the den, only five were observed on Sanak in the summer of 2004 or 2006. Of those five, two were seen solely in predator-free island lakes. Analyzing prehistoric red fox-bird interactions provides insight into Artic fox eradication implications and allows the contrast of Arctic and red fox impacts on birds. This project provides the opportunity to study how humans have altered their ecosystems throughout time.