Hydrobates monorhis
The Swinhoe's Storm Petrel (Hydrobates monorhis) is a small, enigmatic seabird of the Northern Storm Petrel family (Hydrobatidae), known for its entirely dark plumage and deeply forked tail, a key distinguishing feature from other all-dark storm petrels in its range. Averaging 18-21 cm in length with a wingspan of 40-48 cm and weighing around 40-50 grams, it appears almost uniformly sooty-brown or blackish, often showing a subtle paler panel on the upper wing. This highly pelagic species spen...
This truly pelagic species inhabits open ocean waters, often far from land, typically breeding on remote, rocky islands and islets in the North Pacific.
Their diet primarily consists of small crustaceans, fish larvae, cephalopods, and oily substances found on the ocean's surface, often skimmed while flying or pattering on the water.
Swinhoe's Storm Petrels are largely nocturnal at their breeding colonies, arriving and departing under the cover of darkness to avoid predation from gulls and raptors, though they are diurnal at sea. Their foraging strategy involves surface-skimming or 'hydroplaning,' pattering their feet on the ...
Swinhoe's Storm Petrel breeds exclusively in the Northwest Pacific, with primary colonies located on remote islands off the coasts of Japan (including the Ryukyu, Izu, and Ogasawara Islands), South Korea (notably Gyeongnyeolbi-do), and Russia (Kuril and Commander Islands). During the non-breeding...
Least Concern
- Swinhoe's Storm Petrel was only confirmed as a regular breeder in Japan and Korea in the latter half of the 20th century, despite being described in 1867, highlighting its secretive nature. - This species holds the record for one of the most remarkable vagrancy events among birds, with individu...