Unusual behaviour of a Sakhalin Leaf Warbler - presumably health related

Of the huge number of Sakhalin Leaf Warblers on Tsushima this spring, the behaviour of this bird stood out and remains a bit of a puzzle. I can only imagine it wasn't healthy but I've no idea what could have been wrong with it.


It was present on two consecutive days but apparently gone on the third after a general clear-out of warblers. It was very approachable on the ground but when it flew it did so strongly giving no hint of any problem. It occasionally flew up into overhanging bushes but mostly it sat somewhere along a 100 metre stretch of roadside verge. We saw it several times that day as the road, along a steep hillside, was an excellent birding spot which we returned to regularly. The bird was always easily picked up on arrival because it was so vocal, which isn't something I'd normally associate with sick individuals. The second day it was mostly in the trees on the downward slope from the road and seemingly feeding well abundance of caterpillars. Looking at the images I have of the bird, I'm now struck that none show legs, it's always sitting. If it had a problem with feet/legs, this may account for it nevertheless being vocal, feeding well and flying strongly.


However, it also had a colour aberation which I presume was due to the onset of whatever health problem it was suffering from. At a glance it could give the impression of having a narrow white rump patch but as can be seen in the following images there was also a faint greyish wash on the back and some lesser wing coverts suggesting perhaps that pigmentation production ceased as these feathers were growing.

It almost looks like a ground nester here, in the leaf litter it habitually kept its tail cocked like this.

In a more open situation it fanned and pumped its tail. Of course Sakhalin do pump their tails anyway but this was very pronounced.

Just once it flopped down in this abnormal position revealing the 'white rump' and pigment deficient feathers on back and lesser wing coverts.

The second day it was in the trees the whole time, and feeding well, but the continuous, vigorous tail pumping was only more apparent in that situation.



Periods of sitting still on a branch vigorously pumping its tail was very different behaviour to the many other Sakhalin Leaf which were very active.

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The next couple of images have nothing to do with this post but I want to tag them on anyway. The former I want to post because it's my best ever shot of this heron species and the latter because the nest is such an amazing structure.

Probably my best ever shot of this rather scarce heron. This is only the second Striated I've seen this year.

Perhaps a case of an ever-growing nest crushing the bush beneath it but I prefer to think this is a very traditional Osprey site which over time is creating its own micro-environment on top of the bare off-shore stack. 

bitterns & small herons

Eurasian Bittern formerly bred at larger reedbeds near the south east of Lake Biwa but habitat reduction had a severe effect. I haven't tried to listen for them in recent years and I'm unsure about their current status but I believe they do still occur. Perhaps Lake Sainoko just to the north would be a better place to try nowadays. Small numbers also occur in the region in winter, I've seen three birds together at Lake Shinji just to the west of Kansai so it's certainly possible here but bitterns being bitterns, aren't always cooperative.

There was a rather atypically behaved bird in a park in Osaka a few years ago. It you were there at the right time, it would parade around on the lawn in front of the reeds giving great views. But what really set it apart was its habit of flying off into the woodland where it would hunt along small streams under closed canopy or sit motionless in sasa on steep wooded hillsides.

   Lurking in sparse sasa on a steep woodland slope, the most improbable Bittern I've seen here.

Yellow Bittern is another bird that can be found at the larger remaining reedbeds at Lake Biwa. There are also some good reedbeds along the Yodo River between Osaka and Kyoto to look for them too. Unfortunately, the large reedbed further upstream on the Uji River at Ogura is harvested then burnt-off each winter and is only beginning to re-grow when the Bitterns are returning.

If there was ever any reliable chance of seeing Schrenck's in Kansai, I'm sure that time has long gone. The only ones I'd seen until recently were at Lake Kasumigaura in Kanto when they were still regular breeders there and a spring migrant on Tsushima. However, in November 2014 an obliging individual turned up at a small pond in Nishinomya, Hyogo and provided wonderful photographic opportunities for those with better equipment than me.

Schrenck's Bittern, November 2014.

Cinnamon Bittern is no more likely to occur in Kansai but it is reasonably common in the Nansei Islands and can be seen easily at Kijyoka, Okinawa.

Female Cinnamon Bittern Kijyoka, Okinawa.

Male Cinnamon Bittern, Kijyoka, Okinawa. This is without question the best place I've visited to see this species with several flying around and reasonably approachable by car.

Striated Heron isn't rare in Kansai but it is hard to find, not just because it's an unobtrusive and solitary species but also the population density seems low. Having said that I used to see them more often than I do now. The bird below on the Katsura River is unusual in such an open setting, the September date suggests it's a migrant. Local birds are more often found further up stream along wooded stretches of river.

Straiated Heron, Katsura River, Kyoto city. 

                                  Japanese Night Heron, Osaka Castle Park, April 2013.

                                 Japanese Night Heron, Osaka Castle Park, April 2013.

Japanese Night Heron breeds in Kyoto prefecture forests but is difficult to find and the average visitor probably wouldn't want to invest the time listening out for singing males night after night with no guarantee of seeing one. Spring migrants can often be found on islands in the Japan Sea but perhaps the best chance a visitor has of seeing one is if their trip coincides with the arrival of a migrant in a city park. This isn't quite as improbable as it sounds because birds do drop into parks with reasonable regularity. There have been two in Osaka city this year (2013) and it isn't unusual for them to stay two or three days. Interestingly these birds seem to show no fear of humans, unlike birds in the forests, and I remember one in Kyoto Imperial Palace Park strolling between tripod legs, causing confusion and amusement amongst the photographers. No doubt for every bird stopping off in a park there must be many more moving through surrounding forests and I've bumped into three September/October migrants at Mt.Inari in Kyoto as well as one or two others in the area. Apart from seabirds this is perhaps the most difficult species for a visiting birder to connect with.

Malayan Night Heron can't be found in Kansai but is easily seen in the Yaeyama Islands in the far south. Driving on rainy nights on Iriomote it's possible to get great headlight views of several birds taking advantage of all the frogs crossing the wet roads. They can also be found during the day, usually asleep in village gardens or more actively foraging in the forest, particularly on wet days.

Black-crowned Night Heron on the other hand is a common breeder in Kansai and they're easy to see in the centre of Kyoto city on the Kamogawa from the breeding season when adults are fishing round the clock and through summer when juveniles start to appear. As with many herons, small weirs along the river through the city are a focal point. While larger species might wade into the faster water the Night Herons are usually standing hunched on the bank. At other times they can often be heard overhead just after nightfall as they make their way to feeding areas. There are a number of roosts at temples and shrines for example at a small pond on the north side of the main precinct of Fushimi Inari Shrine.

       Presumably a sub-adult with bi-coloured bill and grey in the crown on the Katrura River, Kyoto city.

A roosting juvenile along the Uji River, Kyoto city.

Chinese Pond Heron is definitely not to be expected in Kansai, though it is regular on islands in the Japan Sea, particularly in spring.

Presumed 2cy on Tsushima, early May 2012.

Adult Mishima, early May 2005.

Adult Yonaguni, early April 2013.