I got the following email from Kolbjorn Schjolberg from his home in Panaga, Brunei, a few days ago:
This afternoon I was sitting outside relaxing after my son’s birthday party when a group of 8 starlings landed in a tree some 400 m away. “Luckily” I had my scope with me and I immediately spotted one with a striking wingbar. “Coincidentally” I had the digiscoping equipment an armlength away, and I got a few poor but yet documentary pics, as attached. (All photos: Panaga, Brunei, 7 Sep 2013, (c) Kolbjorn Schjolberg.)
The default migratory starling in Borneo is Chestnut-cheeked, which breeds in Japan and winters mainly in the Philippines and northern Borneo. Although most of the bird is hidden here, the underparts, except for the white lower belly, appear uniform pale buff. Kolbjorn noted in the field that the underside was “uniformly pale”. Chestnut-cheeked will often show a fairly clear contrast between the buff flanks and upper breast and white central lower brest and belly (see this pic), but admittedly, this is not exactly a clearcut diagnostic feature.
This photo shows plain, unmarked tertials. Several field guides suggest that plain dark tertials are a feature of Chestnut-cheeked, whereas Purple-backed should have pale tips. However, a quick survey of images on the Oriental Bird Image database, (e.g. this one) shows that birds in autumn may lack these.
Fortunately, the bird moved into the open for a moment, enabling Kolbjorn to fire off one shot. This shows a long white scapular bar which runs from the carpal to the rear of the scapulars, and this is diagnostic of Purple-backed. Chestnut-cheeked shows a variable-sized white patch on the median coverts, but never a white scapular bar (contra Brazil) as far as I can determine.
Purple-backed (Daurian) Starling is the default winter migrant starling in Peninsular Malaysia (it breeds well west of Chestnut-cheekd, in Central and Eastern China), but how rare is it in Borneo?
Mann (2008) and Myers (2009) recognize a single previous record, of a specimen collected in eastern Sarawak in 1892! So, pretty rare!
Congrats to Kolbjorn on a great garden tick. Maybe more of us should be taking our digiscoping kit to our kids’ birthday parites!