This marine species can be found over both pelagic and inshore waters. It feeds mainly on fish and squid which it catches by surface-seizing and shallow plunges. It often associates with other seabirds and will follow fishing boats. Breeding begins in March in colonies on offshore islands, occupying burrows on forested hills. It undergoes transequatorial migration (del Hoyo et al. 1992).

This species is found in the western Pacific, breeding on the coast and on offshore islands of Japan, Russia, and on islands off the coasts of China, North Korea and South Korea. It migrates south during winter, being found off the coasts of Vietnam, New Guinea, the Philippines, Australia, southern India and Sri Lanka (del Hoyo et al. 1992, Praveen et al. 2013). The global population has been estimated to number c. 3,000,000 individuals (Brooke 2004). In Japan, where the majority of the species’s world population breeds, there are 11 islands that are each thought to be inhabited by more than 10,000 breeding pairs (Oka 2004). A recent survey on the island of Nakanokamishima estimated the population at 5,566 individuals and 2,783 nests (Yamamoto et al. 2015). According to islanders, the species appears to have been declining rapidly on Mikura-Jima, but quantitative data are not available (S. Uematsu in litt. 2012). The prevalence of threats from introduced predators suggests that the species is in overall decline; however, further data are required from throughout the species’s range to assess the current population trend.

Conservation and Research Actions Underway
On Mikura-Jima, some management actions have been carried out to control cats (both feral and domestic); these have included neutering and subsequent release (N. Oka per M. Sato in litt. 2012).

Conservation and Research Actions Proposed
Monitor population trends at selected breeding sites throughout its range. Quantify the impacts of introduced predators on all affected breeding islands, and study the potential impact of fisheries bycatch. Implement robust control measures and strengthen existing management actions to alleviate, and if possible eliminate, the threat of introduced predators on all affected breeding islands. Carry out awareness-raising activities on breeding islands to reduce the impacts of human disturbance and introduced mammals.