The bird also breeds at several sites along the mainland coast of Antarctica. At sea, it mainly occurs along the outer edge of the pack ice in summer with water temperatures of −1.5 to 0.5 °C. In winter, it regularly ranges north to around 40°S latitude. It occurs further north in the cool waters of the Humboldt Current, reaching Peru. Small numbers are seen off the coasts of South Africa, southern Australia and New Zealand. Many birds can be washed up on beaches after storms. There are several unconfirmed reports from the west coast of North America. It is a common species with a population of at least 4 million individuals. About a million pairs breed on the South Sandwich Islands alone. The species is not thought to be at risk of extinction and is classed as least concern by Birdlife International. The breeding colonies may contain hundreds of birds and are on cliffs in ice-free areas with the birds arriving in October. The courtship display consists of a pair sitting alongside each other while calling, waving their heads and nibbling and preening each other. The nest is a shallow scrape lined with stone chips. It is built in a spot sheltered from the wind on a ledge or scree slope or in a crevice. A single, white egg is laid during late November or early December. It measures and weighs about . It is incubated for about 45 days with both parents taking turns in stints of 3–9 days. The down feathers of the young birds are initially white apart from a blue-grey wash on the mantle. The second set of down feathers is grey on the upperparts and flanks while the rest of the underparts and the forehead remain white. The young fledge after around 52 days. Poor weather can lead to high mortality rates among eggs and chicks and they are also preyed on by skuas and sheathbills. Breeding success increases as the parents mature, improving from 48% at age 6–8 to 87% at age 18–20. Southern fulmars frequently gather in flocks, often with other species of seabird such as Cape petrels, when there is a concentration of food like a school of krill or around whaling ships and trawlers. Krill and other crustaceans are the most important component of the diet but the species also feeds on small fish such as the Antarctic silverfish and squid such as "Psychroteuthis", "Gonatus" and "Galiteuthis". Food is usually picked from the surface of the water but the bird will occasionally dive.