Overview
Stejneger's Petrel: Small petrel with gray-brown upperparts, dark gray rump, white underparts. Black head, nape, bill. White face. Gray-brown upperwing, black greater coverts and outer primaries forming an M pattern across lower back. Legs and feet are blue-gray. Gray-brown tail mottled with white.
Range and Habitat
Stejneger's Petrel: Endemic breeder at Alejandro Selkirk island in the Juan Fernandez archipelago. Found in the Pacific from Juan Fernandez archipelago to southern California and east of Japan. Pelagic, only comes ashore to breed.
Petrels and Shearwaters (Procellariidae)
ORDER
There are four families of seabirds in the PROCELLARIIFORMES (pronounced pro-sel-lehr-EYE-ih-FOR-meez), an order that includes the dainty storm-petrels, the huge albatrosses, and the shearwaters.
FAMILY TAXONOMY
The shearwaters are in the Procellariidae (pronounced pro-sel-lar-EYE-ih-dee), a family composed of eighty-five species in fourteen genera that roam all oceans of the world.
NORTH AMERICA
In North American waters, thirty-five species of shearwaters in six genera have been identified. Included among these are the thin-winged Pterodrama species of the deep waters such as the Black-capped Petrel, and the stocky, gull-like Northern Fulmar.
KNOWN FOR
Shearwaters are known for the prominent tube-like structures on their beaks that, as with all Procellariiformes, help remove excess sea water. Species such as the Sooty and Short-tailed Shearwaters are also known for their open water, low altitude gliding and tilting mode of flight on straight wings, the tips of which often slice or “shear” through the water’s surface.
PHYSICAL
Shearwaters are seabirds that are medium to large in size with elongated round bodies, medium length tails, long, pointed wings, and webbed feet adapted to their marine environment. Their bills are medium length, narrow, have a small hook on the tip, and are topped with tubular nasal structures.
COLORATION
This dull-colored family is plumaged in dark browns, black, white, and gray. Some species such as the Sooty Shearwater are all dark with silvery wing linings, while others such as the Great Shearwater are dark above and light below. The Black-capped Petrel and related species have gray and white plumage with bold black markings on the head, back, and wings.
GEOGRAPHIC HABITAT
Shearwaters are encountered in deep, marine waters off of both coasts with the deepest waters beyond the continental shelf favored by the petrels of the Pterodrama genus. They only occur on fresh water if blown inland by hurricanes, and on land are only likely to be encountered on northern cliffs and islets that are their breeding grounds.
MIGRATION
Some species undertake very long migrations from breeding areas in the Southern Hemisphere to the waters of the Northern Hemisphere.
HABITS
Shearwaters nest in colonies, and often occur in flocks when foraging. Fish, squid, crustaceans, and other food items are sometimes picked from the surface, but mostly obtained by diving into the water.
CONSERVATION
Populations of several species of shearwaters have been declining with subsequent listing as near-threatened or threatened; these declines likely linked to long-line fishing and global warming. Shearwaters are also easily threatened by disturbances at their breeding grounds.
INTERESTING FACTS
Shearwaters produce an oily substance in their stomachs that is fed to young and which can be vomited as a defense mechanism. Young birds high in fat and oil content are harvested by the Maori people in New Zealand where they are called, “muttonbirds”.