Wedge Rumped Storm Petrel Facts

Name: Wedge Rumped Storm
Family: Hydrobatidae
Scientific name: Oceanodroma tethys
Length: 18-20 cm Wingspan 24-38 cm
Weight: 23 g
Conservation Status: Near Threatened

Category: Sea Birds
Number of Species: 47
Endemic Species: 13

In total, 47 species of sea birds have been recorded in the Galapagos, 19 of which are resident to the Islands. The sea birds therefore account for nearly one third of all the species ever recorded in the islands and about the same proportion of the resident species.

Seabirds can be conveniently divided into 12 groups, as show in the table below. This shows the number of species recorded in each group and summarizes their status. If also shows the number of endemic species and the number of other species which are represented by endemic subspecies. Species are treated as migrants if they occur annually, vagrants being those recorded less frequently.

Category: Sea Birds
Endemic Subspecies: Wedge-rumped Storm-petrel; Elliot's (or White-vented) Storm-petrel

Eight species of Storm Petrels have been recorded in Galapagos, including 3 resident species, 1 migrant and 4 vagrants. Storm-petrels are the smallest of the seabirds with tube-noses (raised nostril-tubes at the base of the bill). They have short to medium-length wings in proportion to their size and usually fly close to the sea with a characteristic gliding flight action interspersed with rapid wing beats. Storm-petrels have longish legs and webbed feet, and the species most likely to be seen in Galapagos are dark with white rumps. The sexes of all species recorded in Galapagos are alike, and immature plumages resemble adult plumage.

Common resident; endemic subspecies tethys. Population estimated at c. 200,000 pairs in 3 colonies. Nests colonially in burrows or crevices, breeding throughout the year but mainly during the cold season (April to October).

Identification:
A medium-sized, relatively long, narrow-winged storm-petrel. Upper parts uniform dark brown with paler brown bar on upper wing and large, triangular-shaped, pure white rump which extends almost to the tip of the tail and to the upper flanks and lateral under tail-coverts. Under parts dark, sometimes with ill-defined pale center to under wings.

Behavior:
Pelagic. Flight fast and rather forceful with deep wing beats and involving much banking and twisting, often high over the waves. Typically flies with wings held bowed and angled slightly forwards. When feeding skips and bounds over the surface, sometimes pattering on the water in a manner reminiscent of Elliot's Storm-petrel. Unique among storm-petrels in visiting the breeding grounds by day and feeding at night. Occasionally follows ships.