First photo: Markhams Storm-Petrel, quite big and diagnostic tail. Next photo: White-vented Storm-Petrel, not easy to distinguish from Wilsons Storm-Petrel. But if you see the white on the vent it resolves the problem.
During the last Lima pelagic 03 of August we saw five species of Storm-Petrel. Here are four of them. Not all of the photos are sharp, but they serve to learn something about the identification of these birds.