Sakhalin Leaf WarblerPhylloscopus borealoides is an East Asian endemic and passage migrant in Shanghai. On plumage and bare parts it is virtually indistinguishable from Pale-legged Leaf Warbler but is readily separable by song and separable with effort by call. shanghaibirding.com is a clearinghouse of information on Sakhalin Leaf Warbler. Read our posts:
Shanghai birders should consider buying Birds of Japan and Birds of Bhutan and the Eastern Himalayas. I served as proofreader of both books, published by Helm Field Guides. Keep Japan on your bookshelf or in your car as you bird the coast of China, and use Bhutan as your first reference in western Yunnan.
Authored by Mark Brazil, Birds of Japan follows Brazil’s 2009 opus, Birds of East Asia, the best field guide for the coastal provinces of China. Birds of Japan sees Brazil returning to his first love, Japan, where Brazil has been active since the 1980s.
Birds of Bhutan and the Eastern Himalayas, by Richard Grimmett, Carol Inskipp, Tim Inskipp, and Sherub, covers not just Bhutan but also the neighboring Indian states of Sikkim and Arunachal Pradesh. All border Tibet, and Arunachal Pradesh extends east to a point only 80 km (50 mi.) from the Dulong Gorge in Yunnan.
Japan and Bhutan each come with introductions to their regions, richly illustrated with maps and photographs. With its detailed “Where to Bird” section, Grimmett et al.’s 38-page opener is as thorough an introduction as a birder is likely to find to the eastern Himalayas. Brazil’s is less extensive but still does justice to a biogeographically complex archipelago that stretches 3000 km (1,900 mi.) from subarctic Hokkaido to the subtropical Ryukyus.
Japan and Bhutan repurpose much artwork from earlier Helm works, Japan drawing from Birds of East Asia and Bhutan from Birds of the Indian Subcontinent. There is, however, much that is new. In Japan no less than 18 new illustrations of White Wagtail are offered, 12 covering the three ssp. (leucopsis, ocularis, lugens) most common on the Chinese coast. Illustrations better than those in Birds of East Asia are provided for Chinese Egret and several species of duck.
Published nearly a decade after East Asia, Japan incorporates many of the ornithological advances made since 2009. For example, in East Asia Brazil incorrectly writes that the calls of Pale-legged and Sakhalin Leaf Warbler are indistinguishable, and the illustrations suggest that the morphological differences between the two species are appreciable. In Japan, Brazil describes the higher-pitched call of Pale-legged, and the new paintings convey more accurately the near indistinguishability of the species on plumage and bare parts.
To a China-based birder, Birds of Japan offers regional interest and usefulness in the coastal provinces, where it can serve as a backup and partial update to Birds of East Asia. Japan also provides a foretaste of a second edition of East Asia. “The publisher has expressed strong interest in a new edition,” Brazil wrote, “and I have the artist already lined up. I am just awaiting a contract” (in litt., 2019).
Bloomsbury touts Birds of Bhutan and the Eastern Himalayas as “the one guide you’ll need on a visit to this incredible corner of Asia.” Including the neighboring Indian states along with Bhutan was an inspired decision, broadening the scope of the book without diminishing its coherence and increasing its usefulness in the Himalayan regions of China. For birders in the Dulong Gorge and at Baihualing, Ruili, and other hotspots in western Yunnan’s Gaoligong Mountains, Bhutan can replace Craig Robson’s Birds of Southeast Asia. Bhutan has better species descriptions than Robson’s sometimes cryptically concise work, and its illustrations excel those in Robson.
Birders in other parts of China will find Bhutan useful. In Himalayan south Tibet, in particular Yadong, wedged between Sikkim and Bhutan, birders will do just fine with Bhutan and only Bhutan in their backpack. Bhutan will prove useful in regions east of Himalayan China, notably Sichuan, as well as on the Tibetan Plateau. In southern Yunnan (Xishuangbanna), whose avifauna is more Southeast Asian than Himalayan, Bhutan can back up Robson.
Like Birds of Japan, Bhutan includes recent ornithological breakthroughs, among them Himalayan Thrush, a species described in 2016 by Alström et al., and Bugun Liocichla, discovered in 2006 in Arunachal Pradesh. Other Himalayan specialties sought after by China-based birders, such as Sclater’s Monal, Fire-tailed Myzornis, and Beautiful Nuthatch, receive ample coverage in the species accounts and introduction of Bhutan.
China sorely lacks good bird books. On the Helm Field Guides bookshelf, there are gaps where works such as Birds of Sichuan and Yunnan and Birds of the Tibetan Plateau should be. Birders in China have long had to cobble together field-guide strategies, using as a major component field guides covering regions of Asia bordering China. One welcome development has been the increasing quality of those guides. Nowhere are the improvements more evident than in Birds of Japan and Birds of Bhutan and the Eastern Himalayas.
Do you own either of the books discussed in this article? Add your review in the comments below.
Brazil, Mark. (2019). Email to author, 9 August.
Featured image: Covers of Birds of Japan (2018) and Birds of Bhutan and the Eastern Himalayas (2019), published by Helm Field Guides/Bloomsbury. (Craig Brelsford)
Century Park, Pudong, Thurs. 5 Oct. 2017, Komatsu Yasuhiko and Craig Brelsford, 39 species. Hiko and I blew past our target of 35 species and added three species to the shanghaibirding.com Century Park all-time bird list.
The new entries on the shanghaibirding.com list are Sakhalin Leaf Warbler, Dusky Warbler, and White-throated Rock Thrush. The new entries on the eBird list are those three plus Japanese Paradise Flycatcher and Taiga Flycatcher.
“Century Park is getting better,” Hiko said. My young friend is right. Century Park is an island of stability amid the sea of change (mainly degradation) that is the natural environment of Shanghai. Ten years ago this month, when Hiko was a tyke of 6, I made my first visit to urban Shanghai’s best birding area. Little has changed. The biggest difference between October 2007 and October 2017 is, the trees are taller. The wooded areas at Century have an ever-stronger woodsy feel.
— Century yielded yet another regional record of Sakhalin Leaf Warbler. Evidence is growing that in the Shanghai area this passage migrant has been neglected and is more common than previously thought. I recently wrote a series of posts, the latest being this one, on distinguishing Sakhalin Leaf Warbler from its sister species Pale-legged Leaf Warbler.
Here is the recording I made of the calling Sakhalin on Thurs. 5 Oct. Apart from a DNA assay, call as well as song is the only reliable way to separate Sakhalin Leaf Warbler from Pale-legged Leaf Warbler. At 4.9 kHz, the “tink” recorded below is a full kilohertz deeper than the call of Pale-legged Leaf Warbler.
Sakhalin Leaf Warbler Phylloscopus borealoides, Century Park (31.219361, 121.551900), Pudong, 5 Oct. 2017 (00:20; 3.9 MB)
— Eurasian Woodcock whizzed overhead on its way to Bird Island (31.217405, 121.554936). The woodcock was going to the one best place for it in the urban park. Bird Island, Century’s sanctuary-within-a-sanctuary, is a bird-friendly, cat-free parcel of woodland cut off from the rest of the park by a moat.
— Great Spotted Woodpecker used to be found mainly on Bird Island. On Thursday we found 2 in other sectors of the park. With the steadily improving woodland in the park, expect Great Spotted Woodpecker to be seen in more and more areas. Century Park is one of the few areas in urban Shanghai where woodpeckers are commonly found.
— Rufous-tailed Robin in undergrowth, ID’d quickly and accurately by Hiko.
— Red-flanked Bluetail, Grey-backed Thrush: common winter visitors to Shanghai and seasonal firsts for Hiko and me.
— White’s Thrush: a healthy 11 taking advantage of the high-quality woodland in the park.
The shanghaibirding.com Century Park all-time list was started in 2006 by former Shanghai resident and shanghaibirding.com contributor Daniel Bengtsson. I have managed the list since 2015. The list is searchable in English, Latin, and Chinese. As an index of the birds of urban Shanghai, the list is unmatched. Again, the link: https://www.shanghaibirding.com/sites/urban-shanghai/century-bird-records/
Featured image: Komatsu Yasuhiko shows off his image of adult-male Mugimaki Flycatcher at Century Park, Shanghai, 5 Oct. 2017. (Craig Brelsford)
On Sun. 17 Sept. 2017 at Pudong’s Cape Nanhui, I achieved a personal first: photos of an unmistakable Sakhalin Leaf WarblerPhylloscopus borealoides. As expected, the photos show a leaf warbler whose plumage and bare parts are virtually indistinguishable from those of Pale-legged Leaf Warbler P. tenellipes. Coupled, however, as they are with sound-recordings of the same individual, ensuring the ID, the photos constitute a rare visual record of Sakhalin Leaf Warbler in Shanghai.
The leaf warbler I found was easily identifiable as a member of the Pale-Sak species pair. It had strikingly pale pink tarsi, an olive-brown crown contrasting with olive-green mantle and wings, a long and creamy supercilium, and faint wing bars on the median and greater coverts.
The bird, which was in Microforest 1, behaved in a way typical of the Pale-Saks I have observed in the Cape Nanhui microforests, eight tiny woodlands that dot the coastline of the cape. Rarely venturing more than 2 m off the ground, the leaf warbler favored low branches and vines for browsing and sturdy low branches for perching. It pumped its tail steadily, called spontaneously, and upon hearing playback of its own call moved in to investigate the source.
Without recording the call of the leaf warbler (call as well as song being a diagnostic separator of Sakhalin and Pale-legged), would I have been able to get an ID? Almost certainly not, said leaf-warbler expert Phil Round:
“I am a bit less sanguine on finding means (other than call frequency or song) to separate all [Pale-Saks]. Even in the hand, it is by no means clear. We can pick out long-winged male Sakhalin, and short-winged female Pale-legged. But there is more overlap than previously realized, and most are in between. There don’t appear to be any 100% consistent wing-formula differences, and plumage and bare-part features, while somewhat indicative, are again less than 100% reliable—especially under field conditions” (Round, in litt., 2016; emphasis mine).
The most convenient separator of Pale-Sak is song, the cricket-like trill of Pale-legged being easily separable from the metallic whistle of Sakhalin. As Shanghai is not in the breeding range of either species, Pale-Sak songs are not often heard in Earth’s Greatest City. I have heard Sakhalin sing only once, on 5 May 2016 at Shanghai’s Zhongshan Park (Brelsford May 2016). The song of Pale-legged I have heard at various locations in Shanghai as well as on its breeding grounds in Heilongjiang (Brelsford June 2016).
Although not as readily distinguishable as the songs, the “tink” calls of Pale-Sak differ markedly and consistently and are a reliable basis for an ID (Yap et al. 2014; Round et al. 2016; Weprincew et al. 1989). Yap et al. say the call of Pale-legged is of a “consistently higher frequency” than the call of Sakhalin. The calls that I have recorded of the two species show a difference in frequency of about 1 kHz, very much in line with others’ findings (Brelsford, August 2017; Brelsford, September 2017).
For birders unaccustomed to Pale-Sak calls, the difference may be hard to detect, especially at windy Cape Nanhui. A sound-recorder (which may be a smartphone) will pick up the difference, and an audio spectrogram will show it graphically. Solid, indisputable ticks, in some cases life ticks, await enterprising birders who sound-record.
In recent months, my work with sound-recordings has helped give Shanghai birders a clearer picture not only of Sakhalin Leaf Warbler but also of Kamchatka Leaf Warbler Phylloscopus examinandus, like Sakhalin a poorly known passage migrant through Shanghai (Brelsford, June 2017). In the case of Pale-Sak in Shanghai, a picture is emerging of overlapping migratory pathways. This finding comports with the findings of Yap et al. at Beidaihe, a thousand kilometers to the north. After analyzing calls obtained at Beidaihe of both Pale-legged and Sakhalin, Yap hypothesizes that in coastal Hebei “the migratory pathways of the two sister species may largely overlap” (2014).
How extensive is the Pale-Sak migratory overlap in Shanghai? How many of the Pale-Saks that we find in Shanghai each spring and autumn are Pale-legged, and how many are Sakhalin? Is there a peak passage time in Shanghai for each species, and if so, when is it?
Answers to these questions are currently unknown, but they are probably knowable, and it is very much possible for the citizen-scientists of Shanghai to be the producers of that knowledge. We only need to change our habits. When it comes to identifying lookalike species such as Pale-legged and Sakhalin Leaf Warbler, birders need to understand that photos do nothing to cut through the muddle. Only sound-recordings lead to indisputable records and a clearer picture of the species in Shanghai.
The sound-recordings and audio spectrograms below show clearly the difference in frequency between the calls of Sakhalin and Pale-legged Leaf Warbler.
Round, Philip D. E-mail message to Craig Brelsford, 18 Oct. 2016. Round’s e-mail message was originally cited in the shanghaibirding.com post “Pale-legged Leaf Warbler & the Shanghai Big 5,” published 26 Sept. 2016 (accessed: 8 Dec 2019).
Round, Philip D., Pierce, Andrew J., Saitoh, Takema, & Shigeta, Yoshimitsu. 2016. Addition of Kamchatka Leaf Warbler Phylloscopus examinandus and Sakhalin Leaf Warbler P. borealoides to Thailand’s Avifauna. Bulletin of the Japan Bird Banding Association 28: 9–21. Available here for download (708 KB) through shanghaibirding.com (accessed: 8 Dec 2019).
Weprincew, B. N., Leonowitsch, W. W. & Netschajew, W. A. 1989. Zur Lebensweise von Phylloscopus borealoides Portenko und Phylloscopus tenellipes Swinhoe. Mitteilungen aus dem Zoologischen Museum in Berlin 65 (Suppl.): 71–80. (German only)
Yap, F., Yong, D. L., Low, B., Cros, E., Foley, C., Lim, K. K. & Rheindt, F. E. 2014. First wintering record of the Sakhalin Leaf Warbler in South East Asia, with notes on vocalisations. BirdingASIA 21: 76–81.
Featured image: Sakhalin Leaf WarblerPhylloscopus borealoides, Cape Nanhui, Shanghai, 17 Sept. 2017. Craig Brelsford photographed and sound-recorded this individual, getting a rare record of the poorly known species in Earth’s Greatest City.
In the wake of my recent post on distinguishing Pale-legged Leaf Warbler from Sakhalin Leaf Warbler by call, I have been hoping to find more members of this species pair in Shanghai. On 4 Sept. 2017 at Pudong’s Cape Nanhui, my hopes were fulfilled in a big way. At the Magic Parking Lot (30.884889, 121.968222), not one but both species were calling.
Below, the recordings I made with my Olympus DM-650 pocket recorder. The first Sakhalin recording was made at Microforest 4 (30.953225, 121.959083), 7.7 km north of the Magic Parking Lot on the coastal road. The others were made at the Magic Parking Lot.
Note the higher frequency of the calls of Pale-legged—on average a full kilohertz higher. The difference is discernible by the keen listener, but nothing tells the story better than the spectrograms.
To summarize what I argued in the previous post: The calls, as well as the very distinctive songs, of Pale-legged Leaf Warbler and Sakhalin Leaf Warbler are diagnostic—that is, they differ markedly and consistently and are a reliable basis for an ID. The diagnosability of the calls of the two species has been affirmed by various researchers, among them Yap et al. (2014; Birding Asia 21: 76–81).
Featured image: Pale-legged/Sakhalin Leaf Warbler, Jiangsu, May. Some of the salient characteristics of Pale-Sak are pointed out. Separating Pale-legged from Sakhalin on the basis of plumage and bare parts is not possible; because this bird was neither singing nor calling, it cannot be determined to which of the two species it belongs. (Craig Brelsford)
Editor’s note: In the photo above, a Pale-legged Leaf Warbler emits its characteristic “tink” call in Microforest 4, Cape Nanhui, Pudong, 27 Aug. 2017. The tink call of Pale-legged is appreciably higher-pitched than that of Sakhalin Leaf Warbler. Distinguishing the two calls is the subject of this post. — Craig Brelsford
Last September, in “Pale-legged Leaf Warbler & the Shanghai Big 5,” I asserted that “Pale-legged Leaf Warbler is safely separable from Sakhalin Leaf Warbler only by song.” I was wrong. Call as well as song is a reliable separator. In this post, I am going to tell you how I arrived at this insight, and I will show you how you too can achieve clear, indisputable ticks of these tricky species through call alone.
Experts since at least as far back as 1989 have been arguing that Pale-legged Leaf WarblerPhylloscopus tenellipes and Sakhalin Leaf WarblerP. borealoides are separable not only by their distinctive songs but also by their calls. Thailand-based birder and shanghaibirding.com contributor Phil Round is among those making that argument. Round and his co-authors write: “[T]he call of P. tenellipes is markedly higher in frequency than that of P. borealoides” (Round et al., “Addition of Kamchatka Leaf Warbler Phylloscopus examinandus and Sakhalin Leaf Warbler P. borealoides to Thailand’s Avifauna,” downloadable through shanghaibirding.com).
If your ear is good, or even if your ear is just average and you have a sound-recorder, then you too can appreciate the higher frequency of the call of Pale-legged. A sound-recorder is important, because if you upload your recordings to databases such as eBird and the Macaulay Library, then you will be able to “see” the sound in the audio spectrogram.
Our first exhibit is the spectrogram of a call I sound-recorded of Sakhalin Leaf Warbler on 8 May 2016 in Cape Nanhui’s Microforest 4 (30.953225, 121.959083). The frequency is 4.8 kilohertz, a number that matches closely the frequency of Sakhalin calls on xeno-canto.org.
Now consider the spectrograms and sound-recordings of Pale-legged Leaf Warbler below. The spectrogram immediately below was recorded by me on 10 June 2016 in my wife Elaine Du’s hometown of Boli, Heilongjiang, part of the breeding range of Pale-legged Leaf Warbler. The call (here a grace note) and song both clock in at about 6 kHz, a frequency a full 25 percent higher than the call of Sakhalin Leaf Warbler and, as with Sakhalin, consistent with the frequencies of Pale-legged calls on xeno-canto.org.
Here is the sound-recording:
Pale-legged Leaf Warbler, call and song, Xidaquan National Forest (45.727751, 130.317316), Boli, Heilongjiang, 10 June 2016 (01:59; 6 MB)
The spectrogram below is of a brief sound-recording I made in Microforest 4 this past Sunday. The song element of this passage migrant is absent (though note that I have heard Pale-legged and Sakhalin singing in Shanghai in spring). The call has a frequency of 5.9 kHz and clearly belongs to Pale-legged Leaf Warbler.
Why should you care about all this? Because prepared birders have a chance to get solid ticks of “Pale-Saks” that are merely calling and not necessarily singing. If you hear a Pale-Sak calling and trust your ear (or better yet, sound-record the call and later analyze the spectrogram), then you may be able to go beyond the safe, boring record of “Pale-legged/Sakhalin Leaf Warbler” to a more satisfying full tick.
Accurate, plentiful records from Shanghai will help researchers such as Round get a clearer picture of the movements and population of these understudied species. As Round et al. write: “Increased sampling of migrants may also resolve the differences in timing of passage between P. examinandus and P. borealis on the one hand, and P. borealoides and P. tenellipes on the other” (“Addition”; hyperlink mine).
What’s more, you do not need to spend much or even know much to record good audio. My Olympus DM-650 costs less than US$250. I have no microphone other than the one built into my pocket recorder, and I possess no parabola. I record in lossless 48kHz .wav. The very scientific-looking spectrograms displayed in this post are generated automatically by eBird and Macaulay.
In Shanghai and throughout China, important facts about common birds such as Pale-legged Leaf Warbler and Sakhalin Leaf Warbler remain unknown. This ornithological semi-wilderness is both difficult and exciting. If we rise to the challenge and become better birders, then we will make new discoveries and blaze a trail of knowledge for future birders to follow.
The illustration above shows Shanghai’s Big 5 Leaf Warblers: Pale-legged Leaf Warbler (1), Arctic Warbler (2), Eastern Crowned Warbler (3), Pallas’s Leaf Warbler (4), and Yellow-browed Warbler (5). In this post, I tell you how to separate Pale-legged and its lookalike Sakhalin Leaf Warbler from the others.
Recently at Cape Nanhui, the birding hotspot in Pudong, my object of observation was Pale-legged Leaf Warbler, one of the Big 5 Leaf Warblers in Shanghai. In both spring and autumn, Phylloscopus tenellipes passes through Earth’s greatest city in considerable numbers. A lookalike species, Sakhalin Leaf WarblerP. borealoides, also has been noted in Shanghai.
In this post, I shall outline the difficulty of distinguishing Pale-legged Leaf Warbler from Sakhalin Leaf Warbler on anything but call and song, and I will show you some of the traits of “Pale-Sak” that set this species pair apart from other leaf warblers.
SONG CAN SAFELY SEPARATE PALE-LEGGED FROM SAKHALIN
Pale-legged Leaf Warbler is safely separable from Sakhalin Leaf Warbler only by song and call. Every other trait of each can occur in the other. Numerous authorities confirm this. Swedish ornithologist Per Alström calls the two species “almost identical” and “virtually indistinguishable except by song” (Alström 2012). Mark Brazil says field separation of Pale-Sak is “uncertain,” and he warns readers to “beware light conditions” (2009). Clement writes that Pale-legged and Sakhalin are “very similar” and claims, dubiously, that the latter is distinguishable from the former “mainly by greener upperparts and lack of wingbars” (2006). Clements goes on to describe juvenile Pale-legged as being “more greenish on upperparts,” which begs the question of whether the greenish Pale-Sak one is observing is an adult Sakhalin or a juvenile Pale-legged. Moreover, a quick look at Oriental Bird Images shows many Sakhalin Leaf Warbler with wing bars.
Thankfully for us birders, the songs of the two species are distinctive and provide the basis for a safe ID. The song of Pale-legged, occasionally heard in Shanghai in May, is a cricket-like trill, that of Sakhalin a high-pitched, three-note whistle.
One day in May, I heard Pale-legged and Sakhalin singing together in Zhongshan Park—proof that Sakhalin passes through Shanghai. Usually, however, birders here are forced to perform the less than satisfying task of assigning the individuals they see to the category “Pale-legged/Sakhalin Leaf Warbler.”
Bottom line: In Shanghai, any Pale-Sak one sees is probably Pale-legged Leaf Warbler, the continental breeder, and not Sakhalin Leaf Warbler, the breeder from the eponymous Russian island plus Hokkaido and Honshu; but to claim certainty about any non-singing individual is the taxonomical version of Russian roulette.
DISTINGUISHING PALE-SAK FROM OTHER LEAF WARBLERS
The Pale-Sak species pair is readily distinguishable from other leaf warblers, in particular the other four members of Shanghai’s Big 5: Pallas’s Leaf WarblerPhylloscopus proregulus, Yellow-browed WarblerP. inornatus, Arctic WarblerP. borealis, and Eastern Crowned WarblerP. coronatus.
Here are a few principles:
— Pale-legged Leaf Warbler and Sakhalin Leaf Warbler are plain, mid-sized to large leaf warblers without even the hint of a coronal stripe.
— Pale-legged/Sakhalin Leaf Warbler has distinctive pink legs and a short bill with a black smudge on the lower mandible, which is pink at the base and tip.
Even on a fast-moving Pale-Sak in poor light, the pink of the bill and especially of the legs is readily seen. The distinctive pale color of these bare parts is a handy tool for distinguishing Pale-Sak from birds in the Arctic Warbler Complex, which like Pale-Sak lack a crown stripe and usually show one or two wing bars. (The Arctic Warbler Complex consists of Arctic WarblerPhylloscopus borealis, Kamchatka Leaf WarblerP. examinandus, and Japanese Leaf WarblerP. xanthodryas. In Shanghai, Arctic Warbler is the most common of the three, migrating through Shanghai every spring and autumn.) The pink coloration also distinguishes Pale-Sak from Dusky WarblerP. fuscatus, an uncommon migrant and winter visitor in Shanghai, and the scarce passage migrant Two-barred WarblerP. plumbeitarsus.
— Pale-legged/Sakhalin Leaf Warbler constantly pumps its tail.
The tail-pumping of Pale-legged/Sakhalin is one of the most distinctive behavioral traits of the species pair. The steady movement usually occurs independently of other muscular actions and is slow enough for the eye to see. The tail-flicking of Arctic Warbler, by contrast, is more spasmodic and is often accompanied by wing-flicking.
— Pale-legged/Sakhalin Leaf Warbler is often found on the lower, thicker branches of trees.
With its ability to forage along thick branches and not just glean from the underside of leaves, Pale-legged/Sakhalin can remind one of a nuthatch. Other species such as Arctic Warbler use the lower branches, but sustained observation shows Pale-Sak more often in those areas. Note: In May and June 2016, I studied Pale-legged Leaf Warbler on its breeding grounds in Heilongjiang. There, amid trees older and taller than one usually sees in Shanghai, I most often noted the species far above my head, in the mid-canopy.
A NOTE ON CALLS
Except for the mainly silent migrant Eastern Crowned Warbler, Shanghai’s Big 5 Leaf Warblers all call in both spring and autumn. The calls are distinctive. The metallic “tink” of Pale-Sak contrasts markedly with the “tzit” of Arctic Warbler, the “dweet” of Pallas’s Leaf Warbler, and the “sweet” of Yellow-browed Warbler.
Sakhalin Leaf Warbler, Cape Nanhui, Shanghai, May (00:15; 1.4 MB)
Arctic Warbler, Jiangsu, May (00:09; 1.9 MB)
Pallas’s Leaf Warbler, Jiangsu, May (00:05; 1.6 MB)
Editor’s note: This post caught the attention of Philip D. Round, a professor at Mahidol University in Bangkok and an expert on leaf warblers. In an e-mail to me, Round writes that as discoveries are made and papers published, separating Pale-legged Leaf Warbler from Sakhalin Leaf Warbler on call may become more widespread. Separation on morphology, by contrast, will be much more difficult, though it may eventually turn out to be possible in the hand.
The following paragraphs are from Round’s e-mail to me:
“I enclose a paper that details the first records of both Kamchatka Leaf Warbler and Sakhalin Leaf Warbler from Thailand. [Editor’s note: the paper, “Addition of Kamchatka Leaf Warbler Phylloscopus examinandus and Sakhalin Leaf Warbler P. borealoides to Thailand’s Avifauna,” is available for download through shanghaibirding.com (708 KB).] This has been rather overtaken by events, as we have now caught into the hundreds of Sakhalin LW, mostly on spring passage, and quite a few more Kamchatka. I have an undergraduate student who has carried out DNA assay on about ten percent of all the Pale-legged and Sakhalin LW caught. For many of these we have also recorded call notes on release. When she comes back from overseas study in January 2017 I hope we’ll get a paper out which publishes details of call-note frequency and DNA results for this large sample, which should show the correlation between species and call-note frequency clearly. (Actually this is moderately and anecdotally well-known already. I think either Frank Lambert or Jonathan Martinez was the first to draw my attention to the difference, and it is mentioned by Yap et al. in BirdingASIA with reference to an overwintering Singapore bird.) [Note: Round is referring to Yap, Francis et al., “First wintering record of the Sakhalin Leaf Warbler Phylloscopus borealoides in South-East Asia, with notes on vocalisations,” BirdingASIA 21 (2014): 76–81.]
“I am a bit less sanguine on finding means (other than by call frequency or song) to separate all birds. Even in the hand, it is by no means clear. We can pick out long-winged male Sakhalin, and short-winged female Pale-legged. But there is more overlap than previously realized, and most are in between. There don’t appear to be any 100% consistent wing-formula differences, and plumage and bare-part features, while somewhat indicative, are again less than 100% reliable—especially under field conditions. But probably we are missing something. The next thing to do is to apply PCA or some other multivariate analysis to figure out reliable means of separation of birds in the hand from our large sample, and also to use the information we have to figure out differences in the timing of passage of the two spp.”
Alström, P. (2012). Identification of Phylloscopus & Seicercus Warblers in China. Notes from presentation given to Beijing Birdwatching Society in November 2012. PDF downloadable here (13 MB). Click here for a 5 MB zip archive containing all 40 pages of the report in JPEG form. Those pages can be synced to your smartphone like photographs and consulted in the field. (Accessed: 8 Dec 2019)
Brazil, M. (2009). Birds of East Asia. Princeton, New Jersey: Princeton University Press.
Clement, P. (2006). Family Sylviidae (Old World Warblers). Pp. 663-4 (Pale-legged Leaf Warbler, Sakhalin Leaf Warbler) in del Hoyo, J., Elliott, A. & Christie, D.A. eds. (2006). Handbook of the Birds of the World. Vol. 11. Old World Flycatchers to Old World Warblers. Lynx Edicions, Barcelona, Spain.
Featured image: Shanghai’s Big 5 leaf warblers. (Craig Brelsford)
Elaine Du and I noted 86 species over the rainy weekend of 7-8 May 2016. We had White-shouldered Starling, Siberian Blue Robin, and Chestnut Bunting on Lesser Yangshan Island and Chinese Egret, Black-faced Spoonbill, and Curlew Sandpiper at Cape Nanhui. I got my best view of Sakhalin Leaf Warbler at Nanhui, and on Yangshan our partner Michael Grunwell got his best view of Yellow-rumped Flycatcher. Other passage migrants were Brown Shrike, Eyebrowed Thrush, Siberian Rubythroat, and season’s first Dark-sided Flycatcher at Cape Nanhui and Blue-and-white Flycatcher on Lesser Yangshan.
The nearly constant rain made birding challenging but had its good points. While depressing our bird count, especially on Sunday (just 62 species), the rain also depressed the number of visitors, giving Nanhui its former wild feel. The lack of tourists and their vehicles on Sunday allowed 9 Black-faced Spoonbill to exploit a good pond just a stone’s throw from the usually busy sea-wall road. The spoonbills, all sub-adults in non-breeding plumage, noted our car and went back to feeding. On that same pond on Saturday, we captured in a single photograph 6 birds representing five species: 2 Black-faced Spoonbill plus Intermediate Egret, Little Egret, Great Egret, and Chinese Egret.
Though rainy, the weather Sunday was not windy; the lack of wind plus lack of cars made Nanhui quiet and good for sound-recording. I got a particularly good recording of Black-browed Reed Warbler and Oriental Reed Warbler. Note the more slowly delivered, more powerful song of the much larger Oriental Reed Warbler.
Black-browed Reed Warbler, Song (01:19; 3.9 MB)
Oriental Reed Warbler, Song (01:00; 3.2 MB)
I also made a recording of Sakhalin Leaf Warbler (00:15; 1.4 MB):
Phylloscopus borealoides was one of my hot topics over the weekend, after the excitement caused by my encounter on 5 May with a Sakhalin Leaf Warbler at Shanghai’s Zhongshan Park. The tink sound I recorded Saturday at Cape Nanhui was delivered faster and at a lower pitch than the majority of tink calls assigned to Pale-legged Leaf Warbler. The call more closely matches the call of Sakhalin Leaf Warbler. For a deeper discussion of the call of Sakhalin, see my post Separating Pale-legged & Sakhalin Leaf Warbler on Call.
Elaine and I came upon three other birds that are hard to ID to species level. The question of Pale or Sand Martin is nettlesome, as is separating Japanese Bush WarblerHorornis diphone canturians from Manchurian Bush Warbler H. borealis borealis. I know that the Shanghai region falls within the breeding range of canturians, but borealis very likely passes through this region, and Kennerley and Pearson suggest that migrating borealis may sing. Certainly some of the canturians/borealis that we see here are breeding canturians; the problem is singling one out with any certainty.
Another problem is the non-calling Cuculus cuckoos one encounters in Shanghai. On size one can often distinguish a well-viewed Lesser Cuckoo Cuculus poliocephalus, and if the eye is seen well one can distinguish the dark iris of Indian Cuckoo C. micropterus. Common Cuckoo C. canorus, Oriental Cuckoo C. optatus, and Himalayan Cuckoo C. saturatus are larger than C. poliocephalus, and unlike C. micropterus have yellow irides. C. optatus and C. saturatus are virtually indistinguishable, but this pair and C. canorus have some differences, among them the often unbarred yellow undertail coverts of C. optatus/saturatus and the thicker barring of those species on the breast and belly.
Common Cuckoo almost certainly breeds in Nanhui, and very soon we should be hearing its famous call. I have recorded neither C. optatus nor C. saturatus in the Shanghai region, I have witnessed C. micropterus in Shanghai, in the Tianmu Mountains, and at Dongtai in Jiangsu, and I have found C. poliocephalus at Dongtai.
In springtime, one encounters Cuculus adults, which if not calling are hard enough to ID; but just wait, come autumn we will be seeing the juveniles coming through. Juveniles never call, and the various Cuculus species in juvenile form resemble each other even more than Cuculus adults.
On Saturday, Elaine and I birded once again with Shanghai-based English birder Michael Grunwell. On Sunday, we birded briefly with Stephan Popp and Xueping Popp, and later Kai Pflug and his wife Jing dropped by.
Featured image: Black-faced Spoonbill in sub-adult plumage, Cape Nanhui. The spoonbills were taking advantage of the rainy weather, using pools just below the sea wall road. The road is busy when the weather is good but on rainy days is quiet. (Craig Brelsford)
Today, 5 May 2016, I got my first-ever record of Sakhalin Leaf Warbler. The bird was singing on the tiny island at the little central pond (31.224111, 121.414194) at Zhongshan Park, Shanghai. Singing nearby was Pale-legged Leaf Warbler.
I saw a Pale-legged or Sakhalin Leaf Warbler, pulled out my iPhone, and played back a recording of Pale-legged. I got no response. I played Sakhalin for a while, got no response, then stopped. I knew not to walk away, but wait. As Shanghai is outside the breeding range of both species, their urge to sing may not be strong, but it is May and the testosterone is flowing. A response may come after a lag.
I was standing at the edge of the little pond, admiring Narcissus Flycatcher. My brain was barely registering the normal background noise being made by Japanese Tit, Light-vented Bulbul, Chinese Blackbird, Chinese Grosbeak, caged Chinese Hwamei, and old folks practicing qigong. Suddenly from the din came an anomalous sound. I trained my attention to the high-pitched whistle. Sakhalin! My playback had apparently been heard and had attracted a Sakhalin to the tree on the island closest to me on the “mainland.” I glimpsed the bird but saw nothing in its plumage or bare parts to tell it from Pale-legged. In the field, the only reliable element separating the two species is song. Sakhalin makes a three-note whistle, very different from the cricket-like trill of Pale-legged. The three-note whistle is exactly what I was hearing.
After a few minutes, the singing stopped, and then, as if on cue, the trill of Pale-legged surged out from the foliage. I again played back Pale-legged recordings and this time got an immediate and very strong response. Making the “tink” call, a Pale-legged flew to my side of the pond and lingered in trees near me. The tink is apparently similar to that of Sakhalin and therefore not a reliable separator. But soon the tink was followed by another trill, and I knew I was looking at Pale-legged.
What luck! There I was, in the middle of Earth’s largest city, hearing the songs of two East Asian leaf warblers, one of them (Sakhalin) little-known. Does urban birding get any better than this?
I sound-recorded both species. In all the recordings, one can hear the din from a busy inner-city park. In the first of the two song fragments of Sakhalin Leaf Warbler, among the species heard in the background is Ashy Minivet.
Sakhalin Leaf Warbler, Song Fragments 1/2 (00:51; 2.8 MB)
Sakhalin Leaf Warbler, Song Fragments 2/2 (00:36; 2.2 MB)
Pale-legged Leaf Warbler, Trill (00:03; 922 KB)
Pale-legged Leaf Warbler, Tink (00:15; 1.4 MB)
Thanks to Jan-Erik Nilsén, Jonathan Martinez, and Jason Loghry for their help in today’s project.
Featured image: Pale-legged/Sakhalin Leaf WarblerPhylloscopus tenellipes/borealoides, Yangkou, Rudong, Jiangsu, 1 May 2014. Some authors note subtle differences in plumage and structure, but the features overlap, making non-singing Pale-legged and Sakhalin virtually indistinguishable in the field. The species pair is distinguishable from other leaf warblers by their very pale, pink legs. The species pump the tail steadily and often cling to tree trunks, somewhat like a nuthatch. Pale-legged breeds in the Russian Far East and northeast China; Sakhalin breeds on Sakhalin Island and in Japan. (Craig Brelsford)