Nial Moores, October 18th
On October 16th, after cancelled travel plans and a disappointing three-hour session at Igidae counting visible migrants, I walked up the SK bank and relocated both the long-staying Long-tailed Shrike Lanius schach and a / the large flock of Eastern Great Tit Parus minor. This flock was first found here on October 10th – a day of northerly winds and heavy migration. On 16th, at least 265 Eastern Great Tit were counted (compared with 270 on the 10th), including groups of several dozen feeding in a sheltered and sun-washed tree-belt and many more feeding low down to the ground. One of these ground-feeders looked a little brighter, even in flight and to the naked eye. I wondered therefore, though with little conviction, whether this might be a Northern Great Tit Parus major. Northern Great Tit has been recorded in the ROK only once before (a specimen found in a tray of Easterns by Park Jong-Gil), and is a species now known to be irrupting into Western Europe. According to Danish birder Jens Thalund, a Northern with a Moscow ring was recovered in eastern Denmark on October 9th this year – a distance of 1500km in a straight line. Looking at the map in Mark Brazil’s field-guide, the nearest breeding Northern Great Tit could be less than 1500km from northern Gangwon Province (so less than 2000km north of Busan). During irruptions, some from among the massive number of Easterns on the move (e.g. 2,400 counted flying out to sea from one point on Socheong on October 21st 2009) might be coming from “the north”. Could irruptions of Easterns therefore sometimes pull a few Northerns with them – even all the way down to Busan?
Lacking much experience with my new camera I took a couple of hurried digiscope images just before this bright bird was flushed into deeper cover by a Eurasian Jay Garrulus glandrius. A further 90 minutes passed, and there was no sign of anything in view but standard-looking Easterns – with the tit flock becoming more agitated due to overhead raptors and several passing crowds of colourful hikers. After multiple odd “can it be” birding moments this autumn (all in Busan), and knowing that I was over-checking every great tit because of that irruption of Northern Great Tit into Europe, I put the bird’s perceived brightness down to tiredness, too many mosquito bites and a disappointingly over-active imagination, and continued my walk on up through the woodland…
Today, I downloaded the images.
The images (Image 1 and Image 2) are indeed extremely poor. Cropped and otherwise unaltered, however, they appear to show a blur-headed great tit sensu lato with much of the underparts more or less evenly yellow, unlike the off-white underparts of an Eastern. Some of this colour might be due to reflected light from the plants, but of interest, in addition to the smoothness of the yellow on the breast sides, the vent also looks contrastingly pale (white or whitish).
In most light conditions, Eastern show neither yellow tones on the underparts, nor any clear contrast between the ground colour of the vent and the breast and belly-sides. Moreover, other Easterns in the same clump of vegetation and in the same light conditions which were digiscoped immediately after did not look similar to the bright individual. The closest was one that seemed to “develop” some greenish-yellow-buff tones to the breast sides (reflected from the plants, as in Image 4), with these tones then disappearing in direct light (Images 3 and 5).
In addition to the underparts, the upperparts in the bright individual also appear, in the images at least, much more yellowy-green than is typical in an Eastern. This bright colour also appears to extend quite far down the upperparts. In apparent contrast, Easterns have a large white nape spot, edged by bright yellowy-green on the upper mantle, which then usually (invariably?) darkens to a rather darker-olive. The scapulars typically appear blue-grey, rather than bluish, and the greater wing-coverts appear almost black, though with bluer edges and broad white tips (Images 6 and 7). Therefore, apart from the mantle, Easterns are quite subtly coloured.
A further search will be made for this bird on my next trip to Igidae. In the meantime, it would be most helpful to receive comments and links to images of bright Eastern Great Tit and east Russian Northern Great Tit for comparison…Thanks in advance!