Although Bulwer's Petrel's main breeding areas in the North Pacific are 
from China through to the Marquessa Island, it has recently been 
suggested that individuals from the East China Sea colonies disperse 
west into the Indian Ocean (Harrison 1983) and therefore possibly into 
Arabian Waters. Appearing wholly sooty-brown at sea, Bulwer's also 
shows pale upperwing coverts forming a wing bar and could possibly be 
confused with a dark-rumped storm petrel if seen alone. Alongside 
Wilson's however, the rather long pointed tail, long wings and the 
general appearance ie more like a dark gadfly petrel rule out this species. 
Matsudaira's Storm-Petrel breeds only on Volcano Island south of Japan 
but has proved to be highly migratory moving westwards to winter in the 
western Indian Ocean seas off the Seychelles, Kenya and Somalia (Bailey 
1968). Although a true storm-petrel, Matsudaira's is one of the largest 
with a wingspan of 56cm (compared to 40cm of Wilson's, Harrison 1987). 
Again a solitary bird at sea would cause problems when size would be 
hard to define. However, Matsudairas should show a pale upper 
wingbar with a rather distinct white 'skua' type flash formed by white 
bases to the outermost primaries. This feature may of course vary on 
individuals and perhaps during moult. 
Swinhoe's Petrel breeds on islands off Japan, southern and western 
Korea and China (Yellow Sea). Like Matsudaira's, Swinhoe's Petrel also 
moves west from the Pacific into the Indian Ocean. It is interesting to note 
that these two species are thought to be the only sea-birds to make this 
bi-oceanal migration (Bailey 1969). Although its range is not fully known 
Swinhoe's has been recorded north to Eilat, at the head of the Red Sea, 
and west to seas off Cape Guardafuc, Somalia (Bailey 1968). Taxonomy 
of this species is complex, with some authorities regarding it as a sub- 
species of Leach's Petrel O leucorhoa. Furthermore the recent discovery 
of 'dark rumped Storm-Petrels' being caught in the North Atlantic 
initially claimed as Swinhoe's have been suggested to be a new species 
for the world (Sea Swallow 40:63). 
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