The Galápagos Petrel (Pterodroma phaeopygia) is a large, long-winged gadfly petrel. The species was once known as the Dark-rumped Petrel, although recent taxonomic changes have eliminated that name from current use. (See also Hawaiian Petrel, from which this species was split.) The local people in the Galápagos Islands often call this species the "patapegada."
The Galapagos Petrel is an endemic marine bird that nests in areas of high humidity in the highlands (generally above 200 m elevation) of five islands of the Galapagos Archipelago (islands San Cristóbal, Santa Cruz, Santiago, Floreana, and Isabela). In the past, the petrel population was severely affected by introduced mammals. These introduced animals depredated and altered the nesting colonies, placing the petrel in the category of Critically Endangered species listed in the Red Book of Threatened Birds. One of the greatest threats to the population of petrels is the presence of the Black Rat (Rattus rattus), an introduced species that is the principal cause of mortality of eggs and hatchlings of the species. Introduced plants have also altered and restricted the nesting habitat. The reproductive period of the petrels covers about eight months of the year. A study carried out in 2002 showed an egg-laying period between March to the end of October, with a peak occurring during the first two weeks of August.