Swinhoe's Storm-Petrel
Hydrobates monorhis
Medium-sized storm-petrel found primarily in the Pacific. Dark brown overall, with buffy carpal bars in upperwing and noticeable white primary shafts at close range. Tristram's and Matsudaira's are similar but noticeably larger (apparent with experience); dark-rumped Leach’s Storm-Petrel very similar but lacks white primary shafts, flies more erratically, on sharply crooked wings. Flight is often relaxed, on wings often held out farther from the body than in Leach’s. Inhabits deepwater areas but occasionally seen near shore during or after storms.
Identification
Swinhoe's storm petrel is a small bird, 18–21 cm in length with a 45–48 cm wingspan, though distinctly larger than the European storm petrel. It is essentially dark brown in all plumages, and has a fluttering flight, pattering on the water surface as it picks planktonic food items from the ocean surface. Unlike the European storm petrel, it does not follow ships.<p>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.
Taxonomy
- Scientific name
- Hydrobates monorhis
- Authority
- (Swinhoe, 1867)
- Order
- Procellariiformes
- Family
- Hydrobatidae
- Genus
- Hydrobates
Range and habitat
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. It spends the rest of the year at sea, ranging into the Indian Ocean and Arabian Sea.<p>It breeds on Verkhovsky Island (7,500 pairs), south of Vladivostok, Russia, and Japan (a minimum of 1,000 pairs). There are little-known populations in China, Taiwan, North Korea and South Korea, and records suggest that breeding may also occur in the North Atlantic. In winter, it migrates south and west to the northern Indian Ocean (Brooke 2004). Sato et al. (2010) also estimate the world population at a minimum of 130,000 pairs, confirming that the species has a very large population. 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. The species nests at six or seven breeding islets in South Korea (Chang-Yong Choi in litt. 2012). There is apparently anecdotal evidence that some colonies are in decline (N. Moores in litt. 2011).
- Breeding range
- IO, PO : Verkhovsky and Karamzhin is. and satellite islets (sw of Vladivostok, Russia), off Honshu, Shikoku and Kyushu (c Japan), Korean Pen., off Shandong and Guangdong (e China) and Taiwan; possibly also Macaronesia (off nw Africa)
- Non-breeding range
- through seas of e Indonesian Arch., Ashmore Reef (nw of Australia) to w, s India and Sri Lanka, Arabian Sea, and off ne African coast, mostly n of Equator
- Migration
- Complete migrants
Conservation
- Population trend
- stable
Photos
Distribution
Bird Calls
Other Birds
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