At a Glance

This is the largest of the dark storm-petrels found off the west coast, and the one most likely to be seen from shore in southern California. It has a buoyant flight with deep wingbeats, low over the waves. The Black Storm-Petrel nests mainly on islands off western Mexico. The first breeding record for the United States was in 1976 on a rock near Santa Barbara Island, and a few may nest elsewhere in the Channel Islands.
Category
Gull-like Birds, Storm-Petrels
Conservation
Low Concern
Habitat
Open Ocean
Region
California
Behavior
Flap/Glide, Hovering
Population
600.000

Range & Identification

Migration & Range Maps

After nesting, moves north regularly as far as central California. Common on Monterey Bay in late summer and fall during years of high water temperature. Most disappear after October, wintering south to waters off Panama and northwestern South America.

Description

9" (23 cm). The largest western storm-petrel. All black; tail rather long, forked. Flies with relatively slow, deep wingbeats.
Size
About the size of a Robin
Color
Black, Gray
Wing Shape
Long, Pointed, Tapered
Tail Shape
Forked, Notched

Songs and Calls

A loud tuck-a-roo, given at nesting colonies.
Call Pattern
Flat
Call Type
Rattle, Raucous, Scream, Trill

Habitat

Open sea. Favors warm ocean waters; off central California, fewer appear during years of colder water temperatures. Generally far offshore, but in southern California and Mexico, may occur regularly within a few miles of the mainland coast. Nests on rocky islands.

Behavior

Eggs

One. White, sometimes with small reddish-brown spots around larger end. Incubation probably by both sexes.

Young

Probably fed by both parents.

Feeding Behavior

Forages mostly by hovering or fluttering low over water and taking items from surface.

Diet

Includes crustaceans, small fish. Diet poorly known. May eat many small fish at times, and has been reported feeding on larval form of the spiny lobster. May also eat small squid. Scavenges floating fat from dead animals at sea.

Nesting

Breeding behavior poorly known. Nests on islands, often in small colonies. Both members of pair may rest in nesting burrow for nearly 3 months before egg-laying. Active around colonies only at night. Adults give staccato calls while flying around colonies, changing to a musical trill when inside the nest. Nest: Site is in small opening among boulders, in crevice in cliff, or in burrow (especially abandoned burrow of Cassin's Auklet). Usually no nest built, sometimes a few bits of plant material.

Climate Vulnerability

Conservation Status

Numbers probably stable. Vulnerable to introduction of predators (such as rats and cats) to nesting islands.