Since 2011, all invasive mammals have been eradicated from Macquarie Island. Overall, the eradications have resulted in major conservation benefits for wildlife, plants, and habitats. We examined the impact of the invasive mammal eradication on brown skuas, the island’s terrestrial apex predator. Rabbits formed a major component of skua diet for over a century, therefore the eradication of rabbits led to population decline of skuas. Additionally, skuas feeding on poisoned rabbit carcases ingested the toxin, leading to skua mortality in the hundreds – a larger immediate impact than the loss of rabbit prey. The loss of rabbits as a prey item reduced brown skua breeding numbers and success. Nest numbers dropped by almost half, although recent recoveries are evident. In the absence of rabbits, most skuas now focus hunting efforts on penguins, which are another important prey of skuas.