Overview
Wedge-rumped Storm-Petrel: Small storm-petrel, black-brown overall with large white patch on rump and central tail. Bill, legs, and feet are black. Feeds far out to sea. Flight is swift and direct, with deep wing beats and much banking and twisting. Often flies high above the surface of the water.
Range and Habitat
Wedge-rumped Storm-Petrel: Breeds on Galapagos Islands and islands off the coast of Peru. In fall and winter is casual off the Pacific Coast north to the central California coast.
Storm-Petrels (Hydrobatidae)
ORDER
A taxonomic order of tube-nosed seabirds, the PROCELLARIIFORMES (pronounced pro-sel-lehr-EYE-ih-FOR-meez) includes large, long-winged families such as the shearwaters and albatrosses, and the much smaller storm-petrels.
FAMILY TAXONOMY
In the Hydrobatidae (pronounced heye-droh-BAH-tih-dee) are included twenty-two species of storm-petrels in seven genera found throughout the oceans of the world.
NORTH AMERICA
Fifteen species of storm-petrels in five genera have occurred in North American waters (including the extinct Guadalupe Storm-Petrel). The sparrow-sized Least Storm-Petrel, the numerous Wilson’s Storm-Petrel, and the rare White-faced Storm-Petrel are members of this maritime family.
KNOWN FOR
The Wilson’s Storm-Petrel is known for the peculiar behavior of pattering its feet on the surface of the water while foraging. Storm-petrels in general are known for being birds of the marine environment that only come to shore to breed.
PHYSICAL
Storm-petrels are small birds with long wings and medium to long tails that can be forked, square, or wedge-like in shape. Their legs are fairly long with webbed feet, and they have rounded pigeon-like heads. The bills of storm-petrels are small with a slightly hooked tip and tube-like nasal structures to expel excess salt.
COLORATION
Except for the gray and white Fork-tailed and White-faced Storm-Petrels, North American members of this family have dark, sooty brown or black plumages. Some species also show a bit of gray in the wings, and white at the base of the tail. The webs of the feet of the Wilson’s Storm-Petrel are yellow (a characteristic rarely visible in field conditions).
GEOGRAPHIC HABITAT
Storm-Petrels are birds that only occur in salt-water habitats and can be found off both the Pacific and Atlantic coasts of North America. Usually, they are only encountered well offshore although the Least and Black Storm-Petrels can sometimes be seen from land.
MIGRATION
Except for the non-migratory Ashy Storm-Petrel, storm-petrels are very long distance migrants, the Wilson’s Storm-Petrel in particular making incredible voyages from its breeding grounds in the Antarctic to waters of the Northern Hemisphere.
HABITS
Storm-Petrels nest in colonies and often forage in flocks that fly low over the water to pick small sea creatures and carrion off the surface. Flight patterns differ by species; some pattering the surface of the water with their feet, others flying in zig-zags and other species with rapid, almost bat-like wing-beats.
CONSERVATION
The Ashy Storm-Petrel is the only endangered North American storm-petrel species. It only breeds on islands off the California and Baja California coasts, and has strongly declined in numbers because of pollution.
INTERESTING FACTS
Like other Procellariiformes, storm-petrels are long-lived for being small birds; some individuals have lived for over thirty years. They are also highly nocturnal when coming to land to avoid depredation by large gulls. The name “petrel” is thought to have been derived from the name “Peter,” and is an allusion between the story of that Christian saint walking on water and the birds’ doing the same thing while foraging.