Long-tailed Skua Stercorarius longicaudus
One, presumed third year, May 14, 2002, at edge of open sea, and start of island archipelago, about 60 Km SW of Mokpo, Shinnan-Gun, Jeollanam Province.
Sea-watching on May 14th 2002 from the rear of the hydrofoil that runs between Mokpo and Daeheuksan Island , NM picked up a small pale-phased skua flying low over the sea (just above wave crest height) in moderate but strengthening winds, at about 100-150 m range. In heavily overcast conditions the lone bird was followed through 8x32 Leica binoculars for about 1 minute as it crossed behind the boat. The clearest and longest views gained (5 -10 seconds at ca100 m) were of its upperparts. Rather more distant side views (at 200-300 m range and greater) were also achieved.
Identification was straightforward and based on the following features: (1) the skua was small and light in structure, somewhat suggestive of a tern or small gull, lighter than either Arctic or especially Pomarine Skuas, with an obviously less powerful flight than either; (2) the bird, against a dark sea background, showed no obvious white in either the upper primaries or in very brief views of the underwing, though when concentrated upon there was a suggestion of a white edge to the outermost shafts; (3) the tail was very long, much longer than is typical in Arctic, though rather shorter than the longest-tailed Long-taileds. In addition, (4) the upperwing showed some contrast between paler coverts and darker flight feathers, and (5) the bird showed overall the often quoted contrast of grey-brown and pale rather than dark brown and pale as is typical in Arctic, set off by a blackish cap.
Although initially identified as a full adult (based on the length of the tail streamers), the presence of (1) faintly darker breast sides and (2) undertail coverts and vent which were not strikingly solidly dark, but instead looked more variegated, allied to (3) the presumed lack of boldly marked uppertail coverts (as the patterning was not noted at the time), suggest strongly that this was possibly an immature bird - perhaps a second or more likely a third calendar year bird.
Although Long-tailed Skuas have apparently not been recorded previously in Korea, it is said to be a regular passage migrant off the east coast of China and Taiwan (MacKinnon and Phillipps, 2000) and it occurs rather more regularly in Japanese waters than suggested by Brazil (1991), especially from April to June and again between September and November. It was recorded several times from a ferry between Fukuoka and Ikinoshima (Nagasaki prefecture) in 1991 and 1992 (pers. obs), a distance less than 200 km from the Korean south coast, and an exceptional 75-100 were recorded on May 21, 1995 close to shore in Fukuoka Prefecture for example (pers. obs, though the Wild Bird Society of Japan, Fukuoka branch newsletter lists only 6 recorded that day). As such it is likely to prove regular in small numbers, especially on migration, through the Korean part of the South Sea.