Swinhoe's Storm Petrel

The Swinhoe's storm petrel, or Swinhoe's petrel (Hydrobates monorhis), is a small seabird of the storm petrel family Hydrobatidae. It is a species cloaked in all-brown plumage, with a wingspan stretching between 45 to 48 centimeters and a body length of 18 to 21 centimeters. This bird is slightly larger than its cousin, the European storm petrel.

Identification Tips

When observing Swinhoe's storm petrel, one will note its dark brown plumage, which remains consistent across all ages and seasons. It exhibits a fluttering flight pattern and is known to patter on the water's surface as it feeds. Unlike the European storm petrel, it does not typically follow ships. Its forked tail, elongated wings, and flight behavior are reminiscent of the Leach's storm petrel, though it lacks the white rump and its call is distinct. Identification can be challenging due to its similarity to other all-dark Hydrobates species.

Habitat

Swinhoe's storm petrel breeds on islands, preferring to nest in rock crevices close to the sea.

Distribution

This bird has a breeding range that includes islands in the northwest Pacific, specifically off the coasts of the Russian Far East, China, Japan, and Korea. After the breeding season, it spends the remainder of the year at sea, extending its range into the Indian Ocean and Arabian Sea.

Behaviour

Swinhoe's storm petrel is strictly nocturnal at breeding sites to avoid predators such as gulls and skuas. It avoids landing on moonlit nights and has limited walking abilities, shuffling to its burrow. At sea, it is pelagic and feeds mainly on the wing by dipping, without the characteristic pattering seen in some relatives.

Song & Calls

The vocalizations of Swinhoe's storm petrel differ from those of the European storm petrel and other similar species, aiding in its identification.

Breeding

The species breeds on various islands, laying a single white egg in a crevice. Notable breeding sites include Verkhovsky Island and several islets in South Korea.

Similar Species

Swinhoe's storm petrel can be confused with other all-dark members of the Hydrobates genus, such as the Leach's storm petrel, but can be differentiated by its lack of a white rump and unique vocalizations.

Diet and Feeding

This species feeds on planktonic food items picked from the ocean surface, often while in flight.

Conservation status

The Swinhoe's storm petrel is currently classified as Near Threatened on the IUCN Red List. The population is expected to face a moderately rapid decline over the next three generations, primarily due to the impact of introduced species.

North Atlantic status

Though primarily a Pacific species, there have been confirmed sightings and records of Swinhoe's storm petrel in the North Atlantic, including the first record on the Selvagens, Madeira, in 1983. Subsequent sightings have occurred in various locations across the North Atlantic and Mediterranean Sea.