[5] It breeds on islands in the northwest Pacific off the Russian Far East, China, Japan and Korea.

It nests in colonies close to the sea in rock crevices and lays a single white egg.

However, Birds Korea (2010) state that c. 100,000 pairs nest on Gugeul Islet, implying that possibly over 75% of the global population breed on one very small island.

In structure it most resembles a Leach's storm petrel with its forked tail, longish wings, and flight behaviour, but does not have a white rump and the call differs.

It is difficult to distinguish from other all-dark Hydrobates species, and the first English record had to be DNA-tested to eliminate the possibility that it was a Leach's storm petrel, since populations of north-eastern Pacific Leach's storm petrels contain individuals that show completely dark rumps.

[6] The population is expected to undergo a moderately rapid decline over the next three generations, owing primarily to the impact of introduced species.