The island is the location of a large colony of harpies, although most only encounter three or four of them at a time, leading to one of the islands alternate names. This island is well-known to mariners and certain merchants. In the winters, when the harpies have migrated to somewhat warmer regions, the island is mined for its abundant deposits of guano. It is said to be extremely strong stuff, but makes the best fertilizer in the world. At one of the highest points of the island is the Harpies' Roost, where the Harpy Sisters (the Four Harpies themselves) are located.