These seabirds tend to stay far from land except in breeding season. Nesting colonies on islands near New Zealand, Australia and Chile attract millions of birds by September or October. Sooty shearwaters use burrows beneath grass and shrubs for nests. Each burrow harbors a single egg incubated for nearly two months.

Chicks hatch in January, and parents embark on long-distance foraging trips lasting from a few days up to two weeks. At sea, shearwaters leap over one another to catch fish, crustaceans and cephalopods during deep dives. After around 97 days, a nestling fledges from its burrow and goes to sea until it reaches breeding age after five or more years.

Bulkier than other shearwaters and distinguished by dark coloration, the sooty has pale patches under its wings that flash in flight.

During their annual migration, sooty shearwaters head northwest toward Japan and the Kamchatka Peninsula before crossing the Pacific and following the California Current southward. Sooties are the most abundant of the six shearwater species that visit the California Current System in summer and early fall, ranging from British Columbia to southern California. This species stays near cool plumes of nutrient-rich water upwelling beside the coast and pursues squid and anchovy.

Up to a million sooty shearwaters may converge on Monterey Bay during summer. They can be viewed from shore in vast flocks resembling clouds of smoke. In September the birds continue their southward migration.

Widely distributed with a worldwide population estimated in the tens of millions, the sooty shearwater has declined recently in some regions. One study linked rising sea surface temperatures to a dramatic drop in summer sightings of sooty shearwaters along the Pacific coast of North America between 1987 and 1994. Shearwaters appear to be sensitive indicators of changes in ocean ecosystems, such as shifts in fish location and population due to warming water temperature.

Longline fisheries that deploy thousands of baited hooks along a single suspended line lure shearwaters to chase the bait. Birds often drown after being snagged by the hook. Weighting the longline to drift deeper than the birds can dive could reduce the unintended impact on shearwaters.

The Rakiura Maori people conduct a culturally significant harvest of sooty shearwaters, known by their Maori name, titi, or muttonbirds. Every April and May, Maori travel to three dozen islands at the southern end of New Zealand to extract chicks from their burrows or catch fledglings as they emerge. Preserved with salt, the birds provide a lasting supply of meat. The Rakiura Maori have teamed with university scientists to study the sustainability of their traditional practice.

• The name "shearwater" refers to the bird's habit of gliding with stiff, still wings between waves just above the water's surface.
• Shearwaters can also "swim" with their wings to pursue prey underwater to a depth of 200 feet (61 m).
• While migrating, sooty shearwaters can travel up to 620 miles (1,000 km) in a single day.
• Sooty shearwaters attract a partner with courtship calls and behavior and then mate for life.
• On August 18, 1961, flocks of sooty shearwaters, likely disoriented from eating toxic algae, flew ashore at Monterey Bay and crashed into homes. The strange event partly inspired Alfred Hitchcock's movie, The Birds.