Seabird population responses after the removal of an introduced predator

Removal of introduced predators is an effective tool for restoration of island‐nesting birds; however, the effects of predator removal on target species recovery remain understudied. Pigeon guillemots ( Cepphus columba ), a crevice‐nesting seabird in the family Alcidae, declined by 95% from 1979 to 2008 at the Naked Island Archipelago (NIA) in Prince William Sound, Alaska, USA, following the introduction of American mink ( Neogale vison ) and the 1989 Exxon Valdez oil spill. Following the initiation of mink removal from guillemot nesting areas in 2014, we studied guillemot breeding biology at the NIA from 2014 to 2023. By 2023 guillemot numbers detected on shoreline transects at the NIA had increased by 3.3 times. The number of active guillemot nests at the NIA increased by 4.7 times in the first 5 years following the initiation of mink removal. During 2014–2023, the numbers of guillemots at other nearby islands where mink were absent decreased 17% and the guillemot population trend throughout Prince William Sound was approximately stable. Following mink removal, we also observed an increase in the proportion of active guillemot nests in substrates accessible to mink and an increase in survival rates of nestling guillemots at the NIA. The immediate recruitment of guillemots to the NIA after the initiation of mink removal suggests that immigration occurred from nearby mink‐free islands. Our results indicate that the removal of mink from guillemot nesting areas at the NIA was effective in initiating the rapid recovery of a declining local breeding population of guillemots that was formerly the largest in the region. Our findings may be applicable to other insular bird populations subjected to predation from invasive species.