Nesting of Blyth’s Leaf Warbler on Doi Inthanon Summit

Mar 11-12, 2017

In the middle of March (2017), I had a great opportunity to observe nest building of a pair of Blyth’s Leaf Warbler (Phylloscopus reguloides assamensis) on Ang Ka, summit of Doi Inthanon National Park, Thailand. The nest was been building on a soil wall beside the car park area, found by Wichyanan Limparungpatthanakij, my senior experienced bird watcher. This is the first nesting record with photograph evidence of this species in Thailand.

Blyth’s Leaf Warbler – Adult with nesting material

Blyth’s Leaf Warbler – Adult with nesting material before jumping into the nest

From my observation, the nest looks like a small shallow scoop concaved into the soil wall. The entrance is quite open, but may be neglected unless thoroughly watch. One of the pair carries nesting material (Mostly bryophyte moss which is abundant on Ang Ka) to the nest, go inside, and decorate the hollow, while another one waits and watches on a small tree above the soil wall until the one comes out. Then both fly away to continue seeking for nesting material.

Blyth’s Leaf Warbler – Adult while decorating nest

Blyth’s Leaf Warbler – Adult while coming out of nest

During one of the mate decorates the nest, another one often sings a full song and also does a Wing Flicking Behaviour.

Blyth’s Leaf Warbler – Wing Flicking/Flapping Behaviour

Wing Flicking/Flapping Behaviour is diagnostic!

Blyth’s Leaf Warbler do their Wing Flicking Behaviour by flapping either of their wings up-down (just one side at the time alternatively). Whereas their couplet, Davison’s Leaf Warbler (Phylloscopus davisoni) flap their wings both sides simultaneously.

By the way, it is still a question what the actual reasons of Wing Flicking Behaviour in both species are. The initial guess could be courtship or territorial behaviour. However, many times, we observe that they also do wing flicking during their routine activity, such as foraging, outside their breeding season. That could be either territorial behaviour or usual behaviour that they normally do.

Blyth’s Leaf Warbler – Under-tail Pattern

Blyth’s Leaf Warbler vs Davison’s Leaf Warbler

Confusion always occurs for the identification of these two species, since their physical appearance is almost the same except under-tail pattern.

The photo above shows the under-tail pattern of Blyth’s Leaf Warbler which are almost grey with the white edges. On the other hands, Davison’s Leaf Warbler have almost white on under-tail feathers (See photo below). Therefore the under-tail pattern is the most important mark for the identification of these two species.

Davison’s Leaf Warbler – Under-tail Pattern

Watching Phylloscopus Warblers is always fun. There are things to learn about their characteristics and behaviours. Although they are very active and naughty, I turn that to be my challenge and acquisition of knowledge, until now LBJ becomes my favourite job!

Davison’s Leaf Warbler, 20 Sep 2015

Davison’s Leaf Warbler (Phylloscopus davisoni)

In montane evergreen forest of the northern part of Thailand, there are three Phylloscopus warblers in Blyth’s and white-tailed complex which look so much alike. First one is in White-tailed complex which is Davison’s Leaf Warbler (Phylloscopus davisoni). Other two are in Blyth’s complex which are Blyth’s Leaf Warbler (P. reguloides assamensis), and Claudia’s Leaf Warbler (P. claudiae).

Davison’s Leaf Warbler (Phylloscopus davisoni) was photographed at Pramahatat Noppamethanedon and Pramahatat Nopphonphusiri on Doi Inthanon

Davison’s Leaf Warbler (2016)

Davison’s Leaf Warbler is always the most common one that you would see in the montane forest. However, due to the resemblance of these three Phylloscopus warblers, the identification becomes inaccurate unless you see the under-tail part which is the best feature to classify Davison’s Leaf Warbler from Blyth’s and Claudia’s Leaf Warbler. The under-tail pattern of Davison’s Leaf Warbler is almost completely white on the outer pair of tail feathers, whereas Blyth’s and Claudia’s are mostly grey with thin white edge on the outer web. The under-tail part of Davison’s Leaf Warbler is shown in picture below.

Davison’s Leaf Warbler – almost completely white under-tail pattern

Davison’s Leaf Warbler (2016)

Davison’s Leaf Warbler – upper part

Davison’s Leaf Wabler (Phylloscopus davisoni)

Davison’s Leaf Warbler – singing

Davison’s Leaf Wabler (Phylloscopus davisoni)

Davison’s Leaf Wabler (Phylloscopus davisoni)

Davison’s Leaf Wabler (Phylloscopus davisoni)