The return of apex predators re-shape population densities of their prey species, creating conflicts and challenges for the conservation and management of both predator and prey populations. The population of white-tailed eagles (Haliaeetus albicilla) in the Baltic Sea has grown rapidly since the 1980s after a previous population collapse, causing growing predation pressure on its prey species. However, little is known about variation in the prey use in the landscape or changes in time. We provide detailed information about the diet of the white-tailed eagle along landscape-scaled gradients and about temporal changes in their diet over 25 years. We used an extensive data set with 7700 identified prey remains collected during the breeding season on the Åland Islands (Finland) 1985–2010. The results support the view of the white-tailed eagle as an opportunistic hunter, preying on the most available prey and switching to other prey when the availability changes.