Where there are birds, there is guano. The dry climate preserves the droppings of seabirds like the cormorant, pelican and especially the penguin. Guano is a valuable resource for Peru to use and export. Peru’s government has restricted guano collection to about two islands a year, enabling the droppings to accumulate. There are armed guards at each of the islands to ward off threats to birds, mostly from fisherman. Some of the Isla San Lorenzo is a Naval Base and access is prohibited.
The workers make walls and smooth the ground along the sides of the hills where the birds nest - somewhat like terraces for grape vines in a less arid climate. When there is harvesting going on, workers rise before dawn to scrape the hardened guano with shovels and small pickaxes.
Mining the guano has caused serious damage to their Humbolt penguin habitats.