On January 17th, a photographer found an unusual leaf warbler at Suan Rot Fai (Wachira Benjathat Park), a park located north of central Bangkok. According to him, he only took one picture of it (which I find very unusual) and the bird showed nuthatch-like behaviour. From that single photo, I suspected that it might be the nominate subspecies “goodsoni” of Hartert’s Leaf Warbler (Phylloscopus goodsoni) which has never been recorded in Thailand before. David Gandy, a local birder in Suan Rot Fai area, later relocated the bird on January 31st and took many more photos of it which helped confirm that it is most likely a “goodsoni” Hartert’s Leaf Warbler indeed.
I visited the park on Monday morning (2 February 2015) before going to work. Only about 5 minutes after arriving at the location where the bird was found, I could locate the bird foraging through the canopy in a nuthatch-like behaviour. There was also a highly vocal Grey-headed Canary-flycatcher foraging nearby which was a good thing since it helped me locate the leaf warbler easily. It is suspected that the canary-flycatcher follows the leaf warbler to catch the insects which are disturbed by the foraging movements of the leaf warbler.
David sent some of his photos to seek opinions from Paul Leader, an expert on Asian Phylloscopus warblers, and here’s what he quoted.
“I would agree that this is nominate goodsoni. Within the ‘Blyth’s complex, only nominate goodsoni shows this degree of yellow and yellow streaking on the underparts, such that it resembles a washed out Sulphur-breasted Warbler more than other members of the Blyth’s complex. All of the other members of the complex have clean white underparts with limited yellow streaking (central breast/belly), and this includes Ph. g. fokhiensis.
However, the nuthatch-like behaviour is shared by other members of the complex, at least by claudiae, and therefore is not diagnostic.”
I followed the bird from around 8.00-8.45 as it foraged through the main branches high up on tree tops and occasionally came down to just about 1.5 m above the ground and disappeared into the canopy again. It was totally an amazing observation and the bird didn’t seem to be particularly skittish, probably because I was the only one there. I guess it would stay around in the same area throughout the winter.
Apart from the leaf warbler, there were actually quite a good number of species in the area. There was one Radde’s Warbler which was unusually confiding. I also spotted a female/immature Asian Paradise Flycatcher, Black-naped Monarchs, a very confiding male White-rumped Shama, a pair of nesting Brown-throated Sunbirds, Yellow-browed Warbler, a fly-over Stork-billed Kingfisher and an Asian Barred Owlet. I guess I’ll be visiting this area of the park more often.