Swinhoe’s Storm Petrel, Oceanodroma monorhis
Swinhoe’s Storm Petrel may also be known as Swinhoe’s Petrel. It is a small, all-brown seabird of the storm petrel family of Hydrobatidae. The breeding habitat is islands in the northwest Pacific off China, Japan, and Korea. When they nest, it’s usually in colonies close to the sea in rock crevices and lays a single white egg. They spend the rest of the year at sea, ranging into the Indian Ocean and Arabian Sea.
Being a small bird, they are only 18 to 21 centimeters in length, and only have a 45 to 48 centimeter wingspan, even though they are obviously larger than the European Storm Petrel. It is essentially dark brown in all the feathers and has a fluttering flight, pattering on the surface of the water as it picks planktonic items of food from the ocean surface. Structurally, it most resembles a Leach’s Storm Petrel, with its forked tail, longish wings, and the flight behavior, but it does not have a white rump and they have different sounding calls. It is hard to distinguish them from other all-dark Oceandroma species, and the first English record had to be DNA-tested to get rid of the possibility that it was a Leach’s Storm Petrel, because populations of northeastern Pacific Leach’s Storm Petrels include individuals showing completely dark rumps.
This petrel is strictly nocturnal at the breeding sites to avoid predation by gulls and skuas, and will even avoid coming to land on clear moonlit nights. Just like most petrels, their walking ability is limited to a short shuffle to the burrow. With it being strictly pelagic outside the breeding season, and with its remote breeding sites, it is very difficult to see the Swinhoe’s Storm Petrel from land. Only during storms this species might be pushed into headlands, but even then an out of range bird would probably defy definite identification.
Being widespread throughout its large location, the Swinhoe’s Storm Petrel was previously classified as Least Concern on the IUCN Red List of Threatened Species, but it was uplisted to Near Threatened in 2012.
Image Caption: Oceanodroma monorhis, Swinhoe’s Storm-petrel. Credit: Catalogue of the birds in the British Museum. Volume 25/Joseph Smit/Wikipedia