Are the harpy eagles poisonous

First, let's distinguish between venomous and toxic, instead of "poisonous." Venomous animals use a special chemical to kill or subdue prey, while toxic animal have some chemical that makes predators sick, although they may die from it. The first is offensive, the second, defensive.

There are no venomous birds. Raptors rely on beaks and talons. There is one bird, the hooded pitohui, which may be considered toxic, since its diet includes a toxic beetle it's learned to tolerate. The toxin passes into its feathers and makes the bird seriously untasty.