Wedge-rumped Storm-petrel (Oceanodroma tethys)

Wedge-rumped Storm-petrel

[order] PROCELLARIIFORMES | [family] Hydrobatidae | [latin] Oceanodroma tethys | [authority] Bonaparte, 1852 | [UK] Wedge-rumped Storm-petrel | [FR] Oceanite tethys | [DE] Galapagos-Wellenlaufer | [ES] Paino de las Galapagos | [NL] Galapagosstormvogeltje


Monotypic species


Storm-petrels are rather small and often dark colored tubenoses with a world wide distribution. All have fine black bills with very pronounced tubes. Storm Petrels are separated in two groups: the long legged, Southern Hemisphere birds subfamily Oceanitinae and the shorter legged species of more northern seas the subfamily Hydrobatinae. The first groups shows more morphological differences than the second. The genera are characterised on colour patterns, the condition of the nasal tubes, tail shape, structure of claws and proportions of the leg bones. The genus Oceanodroma consists of medium-sized petrels; plumage dark or greyish, often with pale rumps; tail more or less forked; tarsus short , middle toe with claw and scutellate; claws narrow.

Physical charateristics

A large white and triangular patch on the rump is distinctive. The uppertail appears rather dull white because of dark feather-shafts. The rest of the plumage is blackish brown with a paler diagonal bar across upper surface of the wings. Bill and legs dark. Males and females are similar.

wingspan min.: 34 cm wingspan max.: 38 cm
size min.: 18 cm size max.: 20 cm
incubation min.: 41 days incubation max.: 42 days
fledging min.: 73 days fledging max.: 77 days
broods: 1   eggs min.: 1  
      eggs max.: 1  


Pacific Ocean : East. This species can be found off the coast of North America and South America, from Baja California (Mexico) in the north to central Chile in the south. It breeds on the Galapagos Islands, Ecuador, and on Pescadores and San Gallan Islands, Peru


This marine species can be found over pelagic waters usually well offshore except when near colonies.


During breeding it forms colonies on cliffs or lava fields, nesting in rock crevices or under vegetation cover
It is a monogamous species. The nest is placed in a rock crevice or burrow in rocks or bushes. Puts 1 egg, white, which is incubation for about 41 – 42 days in c. 5 day stints. Both parents incubate the egg and the young is brooded for about 2 days. The young fledge after 76 days.

Feeding habits

It feeds mostly on small fish, squid and crustaceans caught on the wing by pattering and dipping, or by surface-seizing while sitting on the water. It feeds mainly at night. Does not follow ships but is often attracted to chum and offal.

Video Wedge-rumped Storm-petrel


copyright: Anna Motis


This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Wedge-rumped Storm-petrel status Least Concern


Some birds present throughout year at Galapagos, but most disperse following Humboldt Current, as do Peruvian population. Vagrant N to California.

Distribution map

Wedge-rumped Storm-petrel distribution range map

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