The harpy eagle (Harpia harpyja) is one of the main predators of arboreal mammals in the neotropics, affecting the ecology and behaviour these species. Knowledge of harpy eagle diets across their geographical range is patchy, the ability of harpy eagles to adapt to changing habitats is still open to question. The three main species in the diet of harpy eagles nesting at Tambopata were porcupines (Coendou sp.) (n = 7) howler monkeys (Alouatta sara) (n = 6) and two-toed sloths (Choloepus didactylus) (n = 4), all species that do well in disturbed forests. We conclude that harpy eagles can reproduce in secondary forests, feeding on abundant disturbance-tolerant species, if they themselves are not hunted and their nesting trees are conserved. Harpy eagle nests have a high value for tourism, and strategies that allow landowners to benefit from harpy eagles nesting on their property through revenues from tourism may be instrumental in incentivising the conservation of forests and emergent trees, and the regeneration of forests in anthropogenic landscapes.