It breeds on inaccessible islands in the colder northern areas of the Atlantic and Pacific Oceans. It nests in colonies close to the sea in well concealed areas such as rock crevices, shallow burrows, or even logs. It lays a single white egg, which often has a faint ring of spots at the large end. This storm petrel is strictly nocturnal at the breeding sites to avoid predation by gulls and skuas, and even avoids coming to land on clear, moonlit nights. The largest colony of Leach's storm petrels can be found on Baccalieu Island of eastern Canada, an ecological reserve with more than 3 million pairs of the birds.