Here comes the final part of the identification of Blyth’s, Claudia’s and Davison’s Leaf Warbler. Apart from the differences in plumage and feeding behaviour, some people also find using song of each species useful for identification. Personally, I could never be confident when trying to distinguish the songs of Blyth’s and Davison’s in the field. They are so similar, but probably the song of Davison’s is slightly more slurred.
Blyth’s Leaf Warbler‘s song
Davison’s Leaf Warbler‘s song
Try listening to the songs of both species and maybe you can point out something that I couldn’t notice.
Claudia’s Leaf Warbler‘s song
Luckily, Claudia’s has a very different song. The problem is that we don’t get to hear it that often because Claudia’s is only a winter migrant in Thailand unlike the other 2 species. The only time when we can get to hear the song of Claudia’s is before they starting to return to their breeding ground. Instead of having a series of high and low notes, Claudia’s has somewhat a repetition of the same note for most part of the song.
So that’s for the identification using songs. Now let’s see more photos of some unusual individuals that I’ve come across both by myself and on the internet. The characteristics explained in the earlier posts are useful for identifying the ‘typical’ individuals, but you also often find individuals that are different from others.
This first individual obviously shows much yellow on the supercilium and cheek. Its lateral crown stripe, especially on the front side, also seems to be much yellowish. So, should it be a Davison’s Leaf Warbler?
The answer is no. It actually turns out to have a very typical undertail pattern for Blyth’s Leaf Warbler, which I have even used as example in the earlier posts! So this case, once again, reminds that the yellowness of supercilium and face can only be used as a rough guideline. The best way to confirm the identification remains to be the undertail pattern.
Now look at this individual, the supercilium seems pretty yellow but the median crown stripe doesn’t show much yellow tinge. Also, the bill seems to be pretty large.
More photos of the same individual. Structurally, I’d say it looks more like a Blyth’s Leaf Warbler; looking large with more striking bill.
But as it moved up to the higher branches and allowed me to get some undertail shots, I became even more confused. Obviously its outermost tail feather on the left side shows the characteristic of Davison’s Leaf Warbler; completely white, but its outermost tail feather on the right somehow shows a weird strong greyish pattern similar to Blyth’s!
Here again you can see the difference between the two outermost tail feathers. Actually, the one on the left also shows some hint of pale greyish pattern, but I believe that it is because the white outermost tail feather is so thin and translucent that you can actually see through to the tail feather behind it, which is mostly the case.
And it flicked both wings! I’m still confused with this individual but leaning towards more to Davison’s. Any comment or suggestion is highly welcomed.
I received this photo from Thanee, a photographer who is very keen on taking photos of warblers and other LBJs, and I was again slightly puzzled by the yellowness of the bird. This photo was taken at Mae Wong National Park, Kampaengphet Province, which is out of the range of Blyth’s. Judging from this photo, it structurally and behaviourally seems to be Claudia’s Leaf Warbler, showing striking long bill and hanging upside-down on a vertical branch, but the overall yellowness is slightly out of the range of Claudia’s in my opinion. Individuals like this always got me questioning myself “Is it possible for Hartert’s Leaf Warbler (both ssp. fokiensis and goodsoni) to occur in Thailand?” My personal answer is yes, definitely but I don’t think we will ever be sure until one get caught and studied in hand.
This photo was taken at Doi Lang, Chiang Mai by Piyapong. It shows an unusually yellow Davison’s Leaf Warbler. I’ve never seen such individual with much yellow on the plumage, especially the underparts, like this one before. It actually reaches the amount of yellowness normally shown in Kloss’s Leaf Warbler, but the undertail pattern of Kloss’s should be more similar to Blyth’s and Claudia’s, but this photo clearly shows that it has completely white undertail feathers, a characteristic of Davison’s. Very unusual indeed.
And few more interesting photos to end this post with; a Davison’s Leaf Warbler family from Doi Lang. The bird on the left is the parent and on the right is the juvenile. You can see how different they are. The juvenile has a much neater plumage and more distinct markings on the head.
Another photo of (probably) another fledgling. You can see how smallish the bill look! Pretty obvious that it is smaller than the bill of the adult. Also, the supercilium, face, crown stripes and especially the wing bar(!) are much more strikingly yellow. The wing bar almost seems to be yellowish-orange.
And 2 more to really end this post. Remember, always check for the undertail pattern! Have fun identifying them throughout this upcoming birding season in northern Thailand.