Bird News from Nial Moores, Rainer Ertel and Herman Reinhardt
From a fishing boat, an excellent day’s birding, with close encounters with two of 20 Swinhoe’s Storm Petrel, 200+ Common Tern (showing a range of bare part coloration), single Flesh-footed Shearwater, several hundred Streaked Shearwater, 600+ Red-necked Phalarope, a single Pomarine Skua and one or two South Polar Skua: the latter species the highlight for NM at least! With wonderful steering by the boat’s captain, we were able to approach one of the South Polar Skua’s closely – as it first rested on a buoy and then roosted on the sea – allowing Dr. Ertel to take an excellent series of images.
Common Terns Sterna hirundo
Common Terns Sterna hirundo
South Polar Skua Stercorarius maccormicki
South Polar Skua Stercorarius maccormicki
Identification as South Polar (a scarce but apparently regular species in ROK waters, especially between July and October) was supported by examination of a couple of the images by seabird expert David James, who commented,
“My first impression is an adult intermediate-morph South-polar. It is within the realm of darkness to be a Brown Skua, but it seems too warm orangey or pinky-buff on the underparts, a distinctive colour of South-polar. From below it would show considerable contrast between underparts. Another important issue is the scattered pale streaks on the scapulars. These are essentially shaft-streaks, are restricted to the scapulars, and are also characteristically paler and bolder distally. When Brown skua shows pale streaks on the upperparts, they tend to be over a range of tracts, are uniformly white, and tend to be on the outer margins of the feathers… It appears that the complete pre-basic moult is well progressed. The timing seems early for SPSK to me, though it is not well-known and apparently quite variable. But I have definitely seen less advanced moult in late October” (David James, in lit. Sep 16 2011).
Red-necked Phalaropes Phalaropus lobatus
Red-necked Phalarope Phalaropus lobatus
Streaked Shearwaters Calonectris leucomelas
Streaked Shearwaters Calonectris leucomelas
South Polar Skua Stercorarius maccormicki
All photographs © Rainer Ertel/Birds Korea.
At least 11 Oriental honey buzzards heading south across the hills to the west of the HMD Hyundai Mipo Dockyard between, Ulsan 08:50 and 10:00 yesterday morning 16th June 2013. Probably more were with them during the morning, I can confirm only 11 birds, first nine together gliding in migratory mode. I have not seen them in mid June before, is this usual? This position was a regular crossing point for raptors during March to early May mid to late 80’s but since the build up of the HHI construction yards, widening of the Bangeo-jin to downtown main road, including excavation of the adjacent hllside (where Von Schrenks and Yellow bittern once bred) I have not seen many raptors using this point since that time.
Dear AB,
Thank you for your mail. Yes: as you suspect, this indeed seems to be an unusual and noteworthy record: thank you.
As you might know already, Prof. Higuchi along with colleagues in Japan, has for many years been conducting studies on a diverse range of species using satellite transmitters. Some of these studies are summarised in a 2011 paper published in the Journal of Ornithology (and published online by Springer ) – including a study on Japan-breeding Crested Honey Buzzard.
From a quick search on google, I see that this project is still running. A figure pasted today or yesterday shows the location of three sat-tracked Crested Honey Buzzard (one last seen in southern ROK on Jun 6th; and two now in Japan after moving through Korea, crossing into Japan in mid May) (http://trace.ms/hachikuma_prj/?img=jpeg&id=1372058114316).
While some information gaps remain, from studies like these we now know for sure that many of the Crested Honey Buzzard (CHB) that breed in Japan winter in far southeast Asia; and that during northward migration, many of the adults migrate back through China into Korea, down the peninsula into SE ROK, and then southeastward into Japan. From a 2005 paper also by Prof. Higuchi et al., the first birds tracked in this way took about 2.5 months to travel north back to Japan, with Second calendar-year birds believed to remain in the non-breeding area.
These studies arrived at much the the same conclusion as Birds Korea has, using our own observational data: many species are funneled during migration, and use the shortest crossings esp. across the Yellow Sea when they can. Weather systems and seasonal weather patterns also influence the scale and timing of such migration.
From observations on Socheong island and elsewhere in Incheon in other years, we already know that some CHB are still migrating into Korea in early June (presumably from the Shandong Peninsula). Some of these might be breeding in Korea; and some might be heading for points further to the northeast – where longer, colder winters means that insect activity and therefore the breeding cycle of CHB might start much later than in Japan. In Japan, the literature and these studies many birds start to arrive back in breeding areas in Mid-May, with, according to Brazil (1991) egg-laying, incubation and fledging then taking approx. 60-80 days; and southward migration peaking in late Sep-early Oct.
Your observation reveals that in 2013 at least, small flock(s) of CHB were still on the move in Korea as late as mid-June. That such birds were seen heading south past Ulsan suggests that these birds at least were most likely intending a crossing into Japan – for some, perhaps several weeks behind their usual schedule (?).
If the timing is indeed exceptional, I wonder if two contributing causes might have been the colder than average winter we had in parts of Eastern Asia (perhaps delaying some vegetation and insect growth?); and also what seems to have been a wetter and cloudier than average May in at least some parts of southern China. A report from the Hong Kong weather observatory, for example, described May 2013 “as much wetter and gloomier than usual due to the prolonged rainy weather associated with troughs of low pressure and active southwesterly airstream over the South China coastal areas. The total bright sunshine duration in the month was 90.7 hours, only about 65 percent of the normal” (http://www.hko.gov.hk/wxinfo/pastwx/mws201305.htm).
Large migrant raptors like Crested Honey Buzzard tend to prefer sunny conditions, with high visibility and a trailing wind, for migrating large distances – especially across open and largely flat landscapes and the sea.
This year some birds moving north might first have been delayed along sections of the route by persistent heavy rains across lowland Thailand and then by rains over much of southern China. This spring also seemed notable for the lack of strong westerly winds across the Korean part of the Yellow Sea in May. Perhaps, the same Crested Honey Buzzards therefore also needed to migrate up around the Yellow Sea – not crossing from Shandong to Hwanghaenam as a few of them do in a usual year, but instead needing to take a longer route, around the top of the Bohai, through Hebei etc – adding still more time to to their journey.
As my Japanese reading skills are now largely lost, it would be helpful if others could provide a few more details on the sat-tracked birds this year and from observations elsewhere: has this been an exceptional or a fairly average year for migration timing of Crested Honey Buzzard and other East Asian raptors?
Thanks once more for your mail: in combination with other research projects, these kinds of observations can help us to understand much more what is happening to the birds around (and flying over!) us.
Nial Moores
Birds Korea