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Sep 11 2011

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Galapagos Petrel (Pterodroma phaeopygia)

Galapagos Petrel

[order] PROCELLARIIFORMES | [family] Procellariidae | [latin] Pterodroma phaeopygia | [authority] Salvin, 1876 | [UK] Galapagos Petrel | [FR] Petrel des Hawaii | [DE] Hawaii-Sturmvogel | [ES] Paino de las Galapagos | [NL] Hawaii-stormvogel

Subspecies

Genus Species subspecies Region Range
Pterodroma phaeopygia PO c

Genus

Genus Pterodroma, Pseudobulweria and Aphrodroma are also knwon as the Gadfly Petrels. They vary in size from rather small birds such as the Cookilaria-species, measuring about 26 cm, to the much larger and robust representatives of this group like the White-headed Petrel with an overall length of about 43 cm. Their plumages also vary a great deal from species to species; from completely black to light grey mantles and pure white bellies, and with different color phases within species. One feature shared by all of them is the black bill of which the shape also shows much variation. Some species are extremely rare and restricted to a very limited area, other are abundant and wander widely or have unknown pelagic ranges.
The group of the Gadfly Petrels counts over 35 species, mainly from the Southern Hemisphere. There are three genera: Pterodroma with about 30 species, Pseudobulweria counting four and Aphrodroma with only one. Many authors have tried to classify the large number of species of this group and to determine their relationships. This has resulted in a division in several subgenera and the grouping of several species which are considered to have a more or less close relationship. The taxonomic discussion has not come to an end yet: new species have been added or split recently and probably will be in the near future.

Physical charateristics

A medium-sized seabird with long wings, the Galapagos petrel is greyish-black across the upperparts, and white on the forehead and underside. The underwings are edged with black and the legs are pink. The feet are also pink, and have black webbing. The black bill is short and hooked, and like all species of petrel, has tubular nostrils that are united at the top. The tail is wedge-shaped and white in colour. Exceedingly similar to Hawaiian Petrel P. sandwichensis and not certainly distinguishable at sea. On average, has longer wing, tarsus and bill. P. sandwichensis lacks black forehead markings.

Listen to the sound of Galapagos Petrel

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Copyright remark: Most sounds derived from xeno-canto


wingspan min.: 88 cm wingspan max.: 94 cm
size min.: 41 cm size max.: 45 cm
incubation min.: 52 days incubation max.: 56 days
fledging min.: 110 days fledging max.: 117 days
broods: 1   eggs min.: 1  
      eggs max.: 1  

Range

Pacific Ocean : Central. Pterodroma phaeopygia is endemic to the Galapagos Islands, Ecuador, breeding on Santa Cruz, Floreana, Santiago, San Cristobal, Isabela and Pacific Oceanssibly other islands in the archipelago. Between 1978 and 1980, Pacific Oceanpulations on the islands were estimated at 9,000 pairs on Santa Cruz, c.11,250 on Santiago, and c.6,750 on Floreana and San Cristobal. By 1985, the Santa Cruz Pacific Oceanpulation had plummeted to 1,000 pairs and, on Santiago, to less than 500, and numbers on Floreana and presumably San Cristobal were estimated to have declined to c. 2,000 pairs. An extensive survey of Santa Cruz in 2005 located c.300 previously unknown nests, but the island Pacific Oceanpulation totalled just 700 pairs. Estimates for 2008 suggested a total of 4,500-5,000 active nests on all five islands. Birds forage around the islands, but also disperse east and north towards South America and up to 2,000 km south.

Habitat

Pelagic bird. It breeds in the humid highlands between 300-900 m, in burrows or natural cavities, on slopes, in craters, sinkholes, lava tunnels and gullies usually in close proximity to Miconia plants

Reproduction

In preparation for long periods of incubation, the female Galapagos petrel leaves the colony to feed for several weeks before returning between late April and mid May to lay two to four eggs. Returning each year to the same site, the male Galapagos petrel is faithful to both the female and the nest. After laying, the male takes the first incubation shift to allow the female to feed again. They take it in turns to incubate the eggs, until the chicks hatch 54 to 58 days later.

Feeding habits

The adults spend the non-breeding season out at sea, feeding during the day on squid, fish and crustacea driven to the surface by tuna and porpoises. They prey mainly on squirrel fish, flying fish, skipjack tuna and goatfish

Video Galapagos Petrel

copyright: Peter Fraser


Conservation

This species has undergone extremely rapid declines in the past three generations (60 years) and is therefore classified as Critically Endangered.
Up until recently the Galapagos Petrel was considered conspecific with the Hawaiian Petrel (Pterodroma sandwichensis) and known as the Dark-rumped Petrel. Differences in morphometrics, breeding timetable, voice and eventually molecular data led to this separation. At first field identification of these two species was considered impossible although recently subtle differences have been identified which suggests that field identification is not only possible but reliable.
Galapagos Petrel status Critically Endangered

Migration

Probably disperses widely through the pacific to the Humboldt Current.

Distribution map

Galapagos Petrel distribution range map

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