Swinhoe's Storm Petrel

The Swinhoe's storm petrel, or Swinhoe's petrel (Hydrobates monorhis), presents itself as a small seabird with a uniform dark brown plumage. This species, with a length of 18–21 cm and a wingspan of 45–48 cm, is slightly larger than its cousin, the European storm petrel. It is distinguished by its fluttering flight and habit of pattering on the water's surface as it forages.

Identification Tips

When observing Swinhoe's storm petrel, note its all-dark plumage and forked tail, which may remind one of a Leach's storm petrel. However, unlike the Leach's, it lacks a white rump, and its call is distinct. Its identification can be challenging due to similarities with other dark Hydrobates species, and DNA testing is sometimes employed to confirm its identity.

Habitat

Swinhoe's storm petrel breeds in colonies on islands, preferring rocky crevices close to the sea for nesting.

Distribution

This bird breeds in the northwest Pacific, with colonies found off the Russian Far East, China, Japan, and Korea. After the breeding season, it migrates to the Indian Ocean and Arabian Sea, with a range extending into these regions.

Behaviour

The Swinhoe's storm petrel is nocturnal at breeding sites to evade predators such as gulls and skuas. It avoids landing on moonlit nights and is pelagic outside the breeding season. Its ability to walk is limited, and it feeds mainly on the wing by dipping into the water without pattering.

Breeding

This species nests in rock crevices near the sea and lays a single white egg. It has a strong fidelity to its breeding sites, which are often remote and difficult to access.

Similar Species

Swinhoe's storm petrel can be confused with other all-dark members of the genus Hydrobates, and particularly with the Leach's storm petrel, which shares its forked tail and flight behaviour but has a white rump.

Diet and Feeding

The diet consists of planktonic food items picked from the ocean surface, and the bird feeds by dipping while in flight, rather than pattering like some of its relatives.

Conservation status

The IUCN Red List has classified Swinhoe's storm petrel as Near Threatened. The species is facing a moderately rapid decline over the next three generations, primarily due to the impact of introduced species on its breeding islands.