Not a pressure washer, and not a broom.
Dried bird and bat droppings can carry disease when they are disturbed, and dry sweeping, pressure washing, a household vacuum or compressed air all put that material into the air you are standing in. They are also what an untrained crew reaches for first.
We mist the droppings and keep them wet through the whole removal, wear fitted particulate respirators, gloves, eye protection and coveralls, and seal the waste so it stays sealed until disposal. If your roof space has held pigeons for years, say so at the walkthrough, because it changes the method and the price.