Overview

Black-vented Shearwater: Medium shearwater, brown-black upperparts, white underparts, brown mottling on sides of breast and flanks. Dark cap extends below eye. Tail is dark. Eats fish, crustaceans, and squid. Quick low flight with short stiff wingbeats followed by glide. Soars in high winds.

Black-vented Shearwater: Breeds on islands off Baja California. Year-round visitor off the coast of southern California, but most commonly in late fall and winter. Lives on open ocean, only comes ashore to breed.

Voice Text

Generally silent

• It flies close to the waves, its flight more fluttery than that of other shearwaters. It rarely follows ships, but feeds by snatching food from the water's surface and sometimes by diving. It also swims beneath the surface, aided by its wings.
• The Black-vented Shearwater is frequently seen from shore. They are only found in the waters off southern and Baja California, where it nests on isolated islands in the California Current. Natividad Island may host as much as 30-40% of the global population of this species.
• The form that visits California waters has dark under tail coverts and was formerly considered a race of the Manx Shearwater, a resident of the North Atlantic.
• A group of shearwaters are collectively known as an "improbability" of shearwaters.

• Greater Shearwater
• Pink-footed Shearwater
• Cook's Petrel
• Streaked Shearwater
• Buller's Shearwater
• Manx Shearwater
• Stejneger's Petrel
• Audubon's Shearwater
• Little Shearwater

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”.

Author

Gary Owen Dick

Artist

Irina Rud-Volga