page_title: Galápagos petrel
section_title: Reproduction
hierarchical_section_title: Galápagos petrel / Behavior / Reproduction
caption_attribution_description: English: View of Island area
context_page_description: The Galápagos petrel is one of the six endemic seabirds of the Galápagos. Its scientific name derives from Ancient Greek: Pterodroma originates from pteron and dromos, meaning "wing" and "runner", and phaeopygia comes from phaios and pugios, meaning "dusky" and "rump". Members of Pterodroma genus are also called the gadfly petrels because their erratic twisting and turning in flight resemble that of gadflies.
  Known by locals as pata pegada or "web-footed one", Galápagos petrels are highly adapted to the ocean and spend most of their time at sea eating invertebrates and fish. At sea, they are indistinguishable from the Hawaiian petrels: consequently, they were considered the same species for a while. When breeding season arises, they return to their large colonies located on the highlands of some Galápagos islands.
  The populations of Galápagos petrels have declined substantially over the last three generations due to anthropogenic disturbances. Introduced predation and agricultural expansion have decreased the species' overall breeding success, survivability, and quality of habitats and nesting colonies.
context_section_description: Pterodroma species reach sexual maturity at age 5-6 and generally nest once every year from then on. The breeding season occurs at a different time for different Galápagos petrel populations. In Santa Cruz and Santiago, the season starts from March to January; in Isabela, from the end of April to January; in Floreana, from October to August; and in San Cristobal, from May to October. Although some seasons overlap, there is little to no interbreeding between populations. These populations have likely diverged from each other because of their rigid cycle and high fidelity to their mate and nesting site.
  
  Mature individuals dig or take up abandoned rabbit burrows and prepare for nesting by enlarging their burrow and gathering dry vegetation. When finding their life-long partner, male gadfly petrels have different displays to attract females. They exhibit elaborate courtship flights that include aerial chasing, high-speed swoops, and towering which are accompanied by loud calls. Breeding pairs associate in their burrow and engage in mutual preening and series of calls. After copulation, they return to the sea to feed abundantly in preparation for the gestation period and the subsequent long incubation period. During this time, which lasts approximately two weeks, each of the pair will pay short visits to the nest so that others do not think it is deserted.
  Each pair lays one egg that is white and ovate. In a study, the eggs weighed about 17 or 20% of the female body weight, but on average eggs weigh 20-24% of that in all gadfly petrels. The incubation period is about 50 days, and the male and female take turns to incubate the egg for an average of 12 days. While the incubating parents are losing an average of 10-15 g per day, the others are foraging at sea with no evidence that they return to feed their partners. Although the eggs are rarely left unattended, both parents will sometimes leave the nest to forage when food is scarce. As an adaptation to this, the eggs are resistant to the cold. However, the introduced black rat (Rattus rattus) prey on the eggs.
  Upon hatching, chicks are covered by an off-white down on the front and sides of the throat, as well as the center of the belly. Parents take turns feeding them, and they quickly become fat, exceeding the weight of their parents. The Galápagos petrel chicks have also adapted to the scarcity of food as they are resistant to starvation. The second down appears after around 10 days and the feathers, after 5 weeks. Once the chicks are fully feathered and look like molted adults, parents stop their visits. Overall, their nesting success is low.
caption: View of Island area. Floreana island is one the nesting sites of the Galápagos petrel.[12]
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