Predation by mink prevented recovery of pigeon guillemots (Cepphus columba) after the Exxon Valdez oil spill in Prince William Sound, Alaska

Pigeon guillemot (Cepphus columba) populations in Prince William Sound, Alaska, were heavily damaged by the 1989 Exxon Valdez oil spill and showed no recovery even 20 years later. At the Naked Island Group, numbers fell 12% annually from 1990–2008, unlike stable populations nearby. Although residual oil affected guillemots and their prey for at least a decade, invasive American mink became the dominant limiting factor by the late 1990s, driving high egg and chick mortality. Diet data show lipid‑rich fish availability had rebounded, yet predation pressure prevented population growth. These findings highlight how invasive predators can overshadow initial spill impacts and demonstrate that recovery at Naked Island is unlikely without targeted mink‑control management.