It’s been more than 2 months since my last blog post. I’ve been very busy with many things but should be able to dedicate more time to this blog soon. Anyway, this morning Wichyanan Limparungpatthanakij, Ingkayut Sa-ar and I went up to Khao Kheow checkpoint, the highest accessible point in Khao Yai National park to seek one of the least known resident Phylloscopus warblers in Thailand, the Kloss’s Leaf Warbler (P.ogilviegranti), of which Ingkayut recently found just around the checkpoint.
We arrived at the checkpoint around 7AM. The weather was brilliant. The forest seemed lush against bright blue sky and warm morning light… but it was strangely SILENT. We almost didn’t hear or see any bird along the way up to the checkpoint. As we arrived, a Barred Cuckoo Dove was heard cooing deep in the forest along with a Mountain Imperial Pigeon.
After a while, we spotted a mixed species flock which seemed interesting and might contain our main target, the leaf warbler, but turned out it didn’t. We wandered fruitlessly around the checkpoint for about half an hour. Finally, Ingkayut and I heard a Phylloscopus leaf warbler singing from roadside forest. We tried but couldn’t locate the bird. It took us another long while to finally hear, probably, a different bird.
We had to use playback in order to see the bird, otherwise it wouldn’t come out to visibility. Interestingly, the bird didn’t respond so much to the song of P. ogilviegranti that we had but responded more to the song of P. davisoni. We also got some recordings of the song while the bird was singing up close. However, songs of both species sound identical to our ears but we might see some differences when analysed in sonograms.
There are about 27 species of Phylloscopus warblers in Thailand. Only 5 of them are resident! 3 out of 5 are found in northern Thailand, i.e.Ashy-throated Warbler, Davison’s Leaf Warbler and Blyth’s Leaf Warbler, while Kloss’s Leaf Warbler is a very range-restricted species of north-east and south-east. The last one is Mountain Leaf Warbler which can only be found on high mountains in the southernmost part of the country.
Among these resident Phylloscopus warblers, Kloss’s is the least known taxon. Khao Yai is by far the most accessible location to see this species, even though it’s proved to be scarce. Another place where Kloss’s Leaf Warbler is known to occur and even said to be common is Khao Soi Dao which is way more difficult to access. Because of this, we felt blessed to have observe the bird so well and obtained some photos and voice recordings.
After seeing the bird and checking the photos that I took, several identification features can be summarised as follow;
- very distinctive undertail pattern; sort of intermediate between Davison’s and Blyth’s
- habitually more similar to Davison’s than Claudia’s/Hartert’s as it mostly sticks smaller branches and twigs rather than staying close to major trunks; also didn’t show any nuthatch-like behaviour
- relatively more yellow on centre of belly than Davison’s; otherwise, other than undertail pattern, very marginally different
But the easiest way to identify is to see the undertail pattern! Finally, I have a complete collection of undertail view for each member of this complex in Thailand. Ranging from the one with most white on undertail (Davison’s on the far left) to the one with least white (Hartert’s on the far right), the image above should give you some idea of where to look when encountered with these birds.