Experience in Pale-legged V.S. Sakhalin Leaf Warbler in 2017 Autumn

Phylloscopus is always one of our favorite birds, because they are cute, and extremely challenging for a safe ID in most of the cases, especially true for some 'species complex', like Arctic Warbler complex, and today's topic: Pale-legged Leaf Warbler Phylloscopus tenellipes v.s. Sakhalin Leaf Warbler Phylloscopus borealoides.

We have both species in Hong Kong but the status of the latter one is more uncertain. In the past, Sakhalin Leaf Warbler is mainly identified by the timing and showing longer primary projection, which both features are much overlapped with Pale-legged Leaf Warbler. So only song and DNA analysis are thought to be the most reliable features to tell the species. But in fact, call maybe another one, and the summary of our experience in this Autumn as here, as we are lazy birders, the information should not be conclusive.

20/9/2017 Wetland Park
Pale-legged / Sakhalin Leaf Warbler X1
A bird very responsive to Sakhalin song, but sadly it did not call or sing, leaving us an unsolved question.

20/9/2017 Wetland Park
Pale-legged Leaf Warbler X1
ID by call

22/9/2017 Wetland Park
Pale-legged Leaf Warbler X4
ID by call

25/9/2017 Wetland Park
Pale-legged Leaf Warbler X1
ID by call

26/9/2017 Wetland Park
Pale-legged Leaf Warbler X1
ID by call

28/9/2017 Wetland Park
Pale-legged Leaf Warbler X1
ID by call

1/10/2017 Wetland Park
Pale-legged Leaf Warbler X2
ID by call

2/10/2017 Wetland Park
Pale-legged Leaf Warbler X1
ID by call

4/10/2017 Wetland Park
Pale-legged Leaf Warbler X1
ID by call

25/10/2017 Wetland Park
Pale-legged / Sakhalin Leaf Warbler X1
No call no song no ID

7/11/2017 Wetland Park
Sakhalin Leaf Warbler X1
ID by call

10/11/2017 Mount Davis
Pale-legged Leaf Warbler X1
ID by call


SO, from our past experience, listening a Pale-legged call is much commoner, which may mean Pale-legged Leaf is much commoner than Sakhalin in Hong Kong. and one more thing, Sakhalin seems coming HK much later than Pale-legged but again, there is overlapping.

Anyway, how to tell from the call? here's the recording this Autumn.

First, a call ID as Pale-legged Leaf Warbler on 2 Oct.
http://www.xeno-canto.org/393390

Second, a call ID as Pale-legged Leaf Warbler on 10 Nov.
http://www.xeno-canto.org/392762


From sonogram, we can see the call is much above 5k Hz, and approaching nearly 6-7k.

Pale-legged Leaf Warbler

Pale-legged Leaf Warbler

Lets compare to the recordings for a Sakhalin Leaf Warbler on 7 Nov.

http://www.xeno-canto.org/391994
http://www.xeno-canto.org/391992

The sonograms show the call is below or near 5k Hz.

Sakhalin Leaf Warbler

Sakhalin Leaf Warbler

So we can tell the difference of the call, not just by sonograms but in fact by human ear too. Sakhalin Leaf Warbler's call is somehow similar to the one produced by Daurian Redstart Phoenicurus auroreus, We think.

How about appearance? We did not have any photos of (safe) Pale-legged Leaf Warbler, but some of the Sakhalin on 7 Nov, you can try check the OBI for comparison.

Sakhalin Leaf Warbler

Sakhalin Leaf Warbler

From the above, you can see the Sakhalin Leaf Warbler is showing:
1. Pink legs
2. Distinct supercilium
3. Two wingbars, with no contrasting between
4. A rather dark bill with yellow base and a whitish tip

These four features also fit Pale-legged Leaf Warbler, so we think the appearance may not help. For behavior, this Sakhalin did wag its tail, also shared by Pale-legged Leaf Warbler, but sometimes, this bird would forage in mid to upper canopy, which we seldom heard Pale-legged would do the same as suggested in other books.

Any conclusions? In fact no. But after checking some literature and a review on Xeno-canto, we think the call is a really reliable feature to separate this species complex, especially in winter or passing, when the birds do not sing. And as the status of Sakhalin Leaf Warbler in Hong Kong is still uncertain, it is always worth to have a look and listen plus record (!) when you see a Pink-legged Phylloscopus one day.

Some reference here, suggested to read:
http://www.shanghaibirding.com/2017/08/31/pale-sak-call/
http://confoley.com/site/wp-content/uploads/BirdingASIA-21-Sakhalin-Leaf-Warbler.pdf

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Upland Pipit Anthus sylvanus

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Oriental Scops Owl Otus sunia

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A review of my HK birding life 11 - Yellow-browed Warbler Phylloscopus inornatus

Yellow-browed Warbler Phylloscopus inornatus

Another common HK species. I love Phylloscopus very much because of the challenge in identification. We watched. heard and took countless Yellow-browed warblers in 5 years and this photo I love the most, taken in Shek Kong, an extra gift when looking for the rosefinch.

A review of my HK birding life 10 - Eyebrowed Thrush Turdus obscurus

Eyebrowed Thrush Turdus obscurus

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A review of my HK birding life 9 - Verditer Flycatcher Eumyias thalassinus

Verditer Flycatcher Eumyias thalassinus

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A review of my HK birding life 8 - Oriental Plover Charadrius veredus

Oriental Plover Charadrius veredus

I love shorebirds, Oriental Plover is one of them. This species is a Least Concern species and a typical one using the East Asia - Australia flyway. In HK, they can only be found in a short period of time in spring and autumn, making twitching difficult. But we were lucky enough to look at two birds in close distance in one spring.

A review of my HK birding life 7 - Lanceolated Warbler Locustella lanceolata

Lanceolated Warbler Locustella lanceolata

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A review of my HK birding life 6 - Ijima's Leaf Warbler Phylloscopus ijimae

Ijima's Leaf Warbler Phylloscopus ijimae

This little bird is one of my favorite East Asian birds. It only breeds in some isolated islands of Japan and has a poorly known migration route. Because of this, it is suggested to be a Vulnerable species. We tried several times on Po Toi for getting good photos, but still failed. So, We needa go to Miyakejima to try again and also the endemic birds there.

A review of my HK birding life 5 - Yellow-breasted Bunting Emberiza aureola

Yellow-breasted Bunting Emberiza aureola

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Rustic Bunting Emberiza rustica

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Relict Gull Larus relictus

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Oriental Stork Ciconia boyciana

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Siberian Crane Leucogeranus leucogeranus

The most rarest crane in East Asia, formerly placed in genus Grus but now is more generally accepted as its own monotypic genus Leucogeranus. Nearly 90% of its global population winters in Poyang Lake, however, they are facing great stress due to habitat change and hence clarified as an Critically Endangered species in the IUCN Red List. There are two records in HK. And we were very lucky to get a shot of the long-wintering adult with its juvenile, which only stayed for 2-3 days in Mai Po.