Seabirds generally nest on islands free of mammalian predators around the world. However, the introduction of invasive predators to islands, especially by humans, has become one of the greatest limiting factors for seabird populations. Additionally, oil spills and climate change, and their effects on seabird food supplies, have contributed to declines in many seabirds. Together, a combination of these factors can have a devastating impact on certain seabird species. Prince William Sound, Alaska, is one region that has experienced the impacts of all three factors on its seabird populations, especially one seabird in particular, the Pigeon Guillemot.

In 1978, surveys conducted by the U.S. Fish and Wildlife Service estimated the population of Pigeon Guillemots that nested on Naked Island to be about 2,000 guillemots, however, at its lowest point in 2012, only 58 guillemots were counted around these same islands. A climatic regime shift in the North Pacific Ocean during 1976-1977 may have kickstarted this decline by causing significant impacts on both physical and biological conditions, leading to dramatic changes in the distribution and abundance of plankton, crustacean, and fish species. Then, on March 24, 1989, the oil tanker Exxon Valdez struck a reef in Prince William Sound and spilled 43.9 million liters of crude oil. An estimated 2,000 - 6,000 guillemots died from acute oiling throughout the spill-affected area which also brought along many other long-lasting sub-lethal effects.

The Pigeon Guillemot population continued to decrease, and by the late 1990s, researchers determined that since the oil spill, mink predation on guillemot nests and adults was likely the primary factor preventing population recovery and limiting reproductive success. With the lingering effects of the oil spill dwindling, only the heightened predation pressure could be addressed. Control of the introduced mink population at the Naked Island Group was selected as the preferred restoration alternative, which this StoryMap focuses on.

In 2014, the U.S. Fish and Wildlife Service partnered with the USDA APHIS Wildlife Services. Through that partnership, highly experienced trappers were able to remove all invasive mink from the guillemot nesting areas on the Naked Island Group. By 2017, no mink were detected near guillemot nesting areas. With continued guillemot monitoring, researchers documented nearly a 400% increase in guillemots from 2012 to 2023 when 288 guillemots were counted at the Naked Island Group! Now that predation pressure from introduced mink is no longer a limiting factor, the guillemot population on the Naked Island Group will hopefully continue to increase. A number of agencies, academic institutions, and partners contributed funding or expertise to the restoration of the Pigeon Guillemot, including the U.S. Fish and Wildlife Service, the Exxon Valdez Oil Spill Trustee Council, Oregon State University, and USDA APHIS Wildlife Services.

For more information contact Robert Kaler, robert_kaler@fws.gov.