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 very 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.
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.
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, I possess no parabola, and I use no editing software. My editing is limited to snipping off the unusable beginnings and endings of my sound-recordings, which I record in lossless 48kHz .wav. The very scientific-looking spectrograms displayed in this post are generated automatically by eBird and Macaulay.
In Shanghai in 2017, 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.
* Audio spectrograms are available for every sound-recording on xeno-canto.org. On the unique page created for each recording, find the section “Actions” and click “Download full-length sonogram.”
Editor’s note: With more and more birders operating in Shanghai, more and more vagrant birds are bound to be discovered. One possibility is Blyth’s Pipit (photo above, L), a species similar to our familiar Richard’s Pipit (R). In this post, I will teach you how to separate the two.
2016 has been an outstanding birding year in Earth’s largest city. Paddyfield Warbler/Manchurian Reed Warbler, seen at Cape Nanhui on 18 Dec., was the latest in a parade of rare visitors seen in Shanghai in 2016. Our Sightings page has documented the discoveries.
The reason for the surge in good records, I am convinced, is more birders with better skills communicating more effectively. I am proud to say that shanghaibirding.com and the Shanghai Birding WeChat group have played a role.
In the Shanghai area, one species that has not yet been reported is Blyth’s Pipit. Anthus godlewskii breeds mainly in Mongolia, occurs on passage in central China, and winters mainly in India, so any records here would be of extralimitals. It is just the sort of vagrant that a bigger and better birding community could discover here in Shanghai.
The key to getting a Blyth’s in Shanghai is paying attention to the many Richard’s Pipit that we see in the area. Anthus richardi is more or less a passage migrant in the Shanghai area and is recorded here regularly in spring and autumn. Some are present in winter; Elaine Du and I had a “sinensis” last week, the ID’ing of which led to this post.
Richard’s “sinensis” is very similar to Blyth’s, being best told by song, which is rarely heard in the Shanghai area. According to Per Alström et al., whose book Pipits and Wagtails is the authority on Palearctic and Nearctic pipits, the song of Blyth’s is “very characteristic and completely different from [that] of Richard’s” (242). During a trip in July 2015 to the Inner Mongolian prefecture of Hulunbeier, one of the few places in China where Blyth’s breeds, I recorded the song.
Blyth’s Pipit, flight song, recorded 22 July 2015 at a point (48.767866, 116.834183) near Hulun Lake, Inner Mongolia (2.1 MB; 00:32)
The calls of the two species also differ, but less markedly. The flight call of Richard’s is a common bird sound in Shanghai during migration season. The call of Blyth’s is similar enough to “cause problems even for some veteran observers” (Alström et al. 244). For Shanghai birders, even those unfamiliar with Blyth’s, a “Richard’s” with a strange flight call is worth your attention. Listen for what Alström et al. describe as a call “less harsh, softer and more nasal” than Richard’s (244). For reference, review the flight call of Richard’s:
Regarding plumage, the most reliable differentiator of Richard’s and Blyth’s is the pattern of the median coverts. In Blyth’s, a typical adult-type median covert will show well-defined, squarish black centers. In Richard’s, the adult-type median coverts are less clear-cut, rufous-tinged, and triangular. Note that the fresher the plumage, the more reliable this differentiator is.
Another less reliable criterion is structure. Shanghai birders will agree that the first impression a non-“sinensis” Richard’s usually gives is “large pipit.” Other pipits, such as Buff-bellied Pipit, Red-throated Pipit, and Olive-backed Pipit, give a “small pipit” impression.
Alström et al. say, and I having seen Blyth’s can concur, that a birder viewing Blyth’s will get a “small pipit” impression: “The smaller size, lighter build and shorter tail,” the authors write, “are often most apparent in flight, when [Blyth’s] often recalls one of the smaller pipits rather than Richard’s.” Note also that the smaller size and shorter bill, tail, and hind claw of Blyth’s give that species a “better proportioned” look than the larger and heavier Richard’s (237).
The directions above should be seen as guidelines; individual Richard’s and Blyth’s may defy easy categorization, “sinensis” Richard’s even more so. Alström et al. caution against jumping the gun with your ID: “It is crucial to realise that in both species (especially Richard’s) appearance can vary considerably in one and the same individual depending on mood, weather, etc.,” they write. “Also, some Richard’s are structurally very like Blyth’s; this is especially true of southern Chinese Richard’s (‘sinensis’)” (237).
A record of Blyth’s Pipit in Shanghai would shoot to the top of the “Year’s Best” list. The stakes are high, so look diligently, and use caution. Good luck!
PADDYFIELD WARBLER/MANCHURIAN REED WARBLER
On 18 Dec. 2016, a quartet of teenage birders found an acrocephalid in the Magic Parking Lot at Cape Nanhui. The photos by Komatsu Yasuhiko provoked discussion on the WeChat group Shanghai Birding. The consensus is that the bird is either Paddyfield WarblerAcrocephalus agricola or Manchurian Reed WarblerA. tangorum.
In the images above, note the supercilium, which extends behind the eye; dark eye-line; bright white chin and throat; peach breast band and flanks; bill with black upper mandible and pink lower mandible; and peaked head. Those criteria most closely indicate Manchurian Reed Warbler and Paddyfield Warbler.
Paddyfield Warbler winters mainly in India and would be extralimital here; Manchurian Reed Warbler breeds in northeastern China, is listed as Vulnerable and is therefore scarce, and probably passes through Shanghai.
Congratulations to Andy Lee, Komatsu Yasuhiko, Larry Chen, and Archie Jiang for this great Shanghai record.
INTERVIEW WITH PUDONG TV
On Thurs. 15 Dec. at Cape Nanhui my wife Elaine Du and I did an interview with Pudong TV in Chinese. The segment will last five minutes and be aired later this month. (UPDATE, 24 DEC 2016: Segment available here.) In the interview I lamented the losses at Nanhui and spoke glowingly of the possibilities.
MacKinnon asked me for the reasoning behind a wetland reserve at Cape Nanhui. I wrote the following:
THE CASE FOR AN EASILY ACCESSIBLE, WORLD-CLASS WETLAND RESERVE AT CAPE NANHUI, PUDONG, SHANGHAI
(1) Cape Nanhui is of extraordinary environmental importance. The tip of the Shanghai Peninsula between the Yangtze River and Hangzhou Bay, Cape Nanhui is a stepping stone for birds migrating across those bodies of water. Cape Nanhui also holds large reed beds, habitat critical to Reed Parrotbill, Marsh Grassbird, and other species at risk.
The largest component of the city-province of Shanghai is the Shanghai Peninsula, a projection of land between the Yangtze River and Hangzhou Bay. Cape Nanhui is the tip of the peninsula, is a critically important stop for migrating birds, and is completely unprotected. A nature reserve at Cape Nanhui would form a third stepping stone for birds crossing the mouth of the Yangtze, joining the reserves at Chongming Dongtan and Jiuduansha.
(2) Shanghai is clearly under-performing on the conservationist front. More must be done, and a good place to begin is Cape Nanhui.
Nature reserves have been established only on the extreme fringes of the city-province (which is a third the size of Wales). There are no reserves in mainland Pudong, a giant coastal district nearly twice the size of Singapore. Nowhere in this megalopolis can residents without a car enjoy the natural side of Shanghai, a city with an extraordinarily rich natural heritage. There is no known plan to conserve any of the dozens of square kilometers of reclaimed land on Hengsha.
(3) Because it is in the back yard of Shanghai, a city-province of more than 25 million people, a well-run, easily accessible wetland reserve at Cape Nanhui could be the match to light the fire of conservation across all China.
Hundreds of thousands of middle-class children could visit the reserve with their parents using nothing more than the Metro and a quick taxi ride and be sleeping in their own bed that night, dreaming about the wild birds they had seen that day. For millions of parents and their kids, the weekend could be “Saturday, Disney; Sunday, Cape Nanhui Wetland.” A day at a Cape Nanhui Wetland would be an early introduction to the glories of natural Shanghai and would foster an appreciation of the natural world.
If Shanghai can be a world economic center and have world-class airports and a world-class skyline and world-class entertainment such as Disney, then it can and must have an easily accessible, world-class reserve protecting its priceless coastline, reed beds, and migratory birds.
A world-class, easily accessible, wetland nature reserve at Cape Nanhui would become a mecca for birders and achieve world renown, as has been the case with similar reserves such as Mai Po at Hong Kong and Sungei Buloh in Singapore.
Tundra Bean Goose Anser serrirostris 20
Tundra Swan Cygnus columbianus bewickii 19
Common Shelduck Tadorna tadorna 550
Falcated Duck Anas falcata 400
Mallard A. platyrhynchos 80
Eastern Spot-billed Duck A. zonorhyncha 250
Northern Shoveler A. clypeata 300
Northern Pintail A. acuta 120
Eurasian Teal A. crecca 40
Tufted Duck Aythya fuligula 10
Greater Scaup A. marila 3
Common Pheasant Phasianus colchicus 2
Little Grebe Tachybaptus ruficollis 40
Great Crested Grebe Podiceps cristatus 2
Black-necked Grebe P. nigricollis 7
Great Cormorant Phalacrocorax carbo 80
Eurasian Bittern Botaurus stellaris 1
Grey Heron Ardea cinerea 60
Great Egret A. alba 8
Little Egret Egretta garzetta 50
Black-crowned Night Heron Nycticorax nycticorax 7
Eurasian Spoonbill Platalea leucorodia 72
Western Osprey Pandion haliaetus 1
Eastern Marsh Harrier Circus spilonotus 1
Eurasian Coot Fulica atra 50
Hooded Crane Grus monacha 1
Grey Plover Pluvialis squatarola 8
Kentish Plover Charadrius alexandrinus 30
Eurasian Curlew Numenius arquata 1
Dunlin Calidris alpina 70
Spotted Redshank Tringa erythropus 22
Common Greenshank T. nebularia 1
Vega Gull Larus vegae vegae/L. v. mongolicus 21
Spotted Dove Streptopelia chinensis 8
Eurasian Hoopoe Upupa epops 1
Peregrine Falcon Falco peregrinus 1
Long-tailed Shrike Lanius schach 10
Chinese Penduline Tit Remiz consobrinus 20
Light-vented Bulbul Pycnonotus sinensis 7
Dusky Warbler Phylloscopus fuscatus 1
Plain Prinia Prinia inornata 1
Vinous-throated Parrotbill Sinosuthora webbiana 10
Crested Myna Acridotheres cristatellus 50
Pale Thrush Turdus pallidus 2
Dusky Thrush T. eunomus 3
Daurian Redstart Phoenicurus auroreus 3
Eurasian Tree Sparrow Passer montanus 50
White Wagtail Motacilla alba 6
Richard’s Pipit Anthus richardi 1
Buff-bellied Pipit A. rubescens japonicus 15
Chestnut-eared Bunting Emberiza fucata 7
Little Bunting E. pusilla 1
Pallas’s Reed Bunting E. pallasi 1
Alström, Per, Krister Mild & Bill Zetterström. Pipits and Wagtails. Princeton University Press, 2003. This landmark book, co-authored by Shanghai Birding member Per Alström, is my first reference on all things Motacillidae.
Brazil, Mark. Birds of East Asia. Princeton University Press, 2009. Serviceable descriptions of Blyth’s Pipit and Richard’s Pipit. Illustration of “sinensis.” Good coverage of Paddyfield Warbler, Manchurian Reed Warbler.
Brelsford, Craig, moderator. Shanghai Birding, a WeChat chat group. Pipits and reed warblers discussed in detail. To join Shanghai Birding, fill out the form on our Sightings page.
Kennerley, Peter & David Pearson. Reed and Bush Warblers. Christopher Helm, 2010. The world standard on Acrocephalidae, Cettiidae, and Locustellidae.
Svensson, Lars & Killian Mullarney & Dan Zetterström. Collins Bird Guide, 2nd ed. HarperCollins, 1999-2009. Outstanding illustrations of Richard’s Pipit and Blyth’s Pipit by Mullarney.
Editor’s note: The featured image above shows the stunning male Japanese Paradise Flycatcher and serves to introduce this week’s theme: How can birders tell apart the two species of the remarkable genus Terpsiphone that migrate through Shanghai?
Each spring and autumn, two species of paradise flycatcher pass through Earth’s greatest city: Japanese Paradise Flycatcher Terpsiphone atrocaudata atrocaudata and Amur Paradise Flycatcher T. incei. The two species can seem confusingly similar, especially in the poor light of a wood. With a little practice you can tell the males apart, and with a lot of practice you should be able to separate the females. Here is what you need to know:
— If in Shanghai you see a white-morph paradise flycatcher, then by definition you are not looking at Japanese Paradise Flycatcher, and you are almost certainly looking at Amur Paradise Flycatcher.
No white morph exists in Japanese (Mark Brazil, Birds of East Asia). Regarding Amur, among my sources only Brazil expresses doubt about the existence of a white morph. shanghaibirding.com contributor John MacKinnon (A Field Guide to the Birds of China) and C.W. Moeliker (Handbook of the Birds of the World, Vol. 11) assure us that Amur white morph does exist. MacKinnon says that Amur white morph accounts for less than half of adult males.
We know that Amur white morph exists because we have seen it ourselves. On 30 May 2016, Kai Pflug photographed an Amur white morph at Nanhui, the coastal birding site in Shanghai. In May 2010 at Dongzhai, Henan, 680 km inland from Shanghai, I found an Amur white morph.
Could a white morph from a third species occur in Shanghai? Although the movements of paradise flycatchers are “complex and not fully understood” (Moeliker), I think we can presume that it is unlikely. The nearest third species is Oriental Paradise Flycatcher T. affinis saturatior, which according to MacKinnon winters no closer to Shanghai than Guangdong.
— The mantle, wings, rump, and tail of rufous-morph male Amur are rufous-brown; in Japanese, the mantle, wings, and rump are purplish-brown, and the tail is black.
The pictures speak for themselves. In good light you should have little trouble telling the two apart. The cinnamon tones of Amur are often what Shanghai birders notice first.
— Male Japanese has a black head and a black breast, forming a large hood. Amur rufous morph has black head and grey breast, forming a two-tone hood.
The hood of Amur has in addition more of a bluish tint than that of Japanese. Note the blue tint in the hood of Amur bottom left. Note also that the cobalt-blue eye ring of Japanese (top left) tends to be larger than the eye ring of Amur.
The females require more care to separate. Be persistent, get a good view, and try to get a photo. Note the following:
— Compared to Amur female, Japanese female has darker, duller, and less rufous mantle, wings, rump, and tail. Japanese has much darker (nearly all-black) flight feathers and sooty primary coverts.
— In their head and breast coloring, female Japanese and Amur show a pattern similar to that of the males. Whereas Japanese is more concolorous (panels 3 and 4), Amur shows more of a contrast between head and breast (1a, 1b, 2). Both Japanese and Amur female have whitish bellies, but the darker breast of Japanese contrasts more with the whitish belly than is the case with Amur. The head is glossier in Amur than in Japanese, whose crown is dull (inset, Panel 3). Japanese has faint rufous flanks, unlike Amur.
MAINLY SILENT IN SHANGHAI
In Shanghai, you will almost never hear a paradise flycatcher utter a sound. I have a single recording:
Japanese Paradise Flycatcher, call, Nanhui, 24 May 2016 (00:01; 848 KB)
BACKGROUND ON THE SPECIES
Japanese Paradise Flycatcher Terpsiphone atrocaudata and Amur Paradise Flycatcher T. incei breed farther north than any other species in their mainly tropical genus. T. atrocaudata atrocaudata breeds in Korea, Japan, and Taiwan and is highly migratory, wintering as far south as Sumatra. (Birds in Taiwan, however, are largely resident.) T. incei, a monotypic species, is also highly migratory, with a breeding range extending into the Russian Far East and wintering grounds as far south as Java (Moeliker). Japanese is listed by the IUCN as Near Threatened, mainly because of habitat loss on its wintering grounds.
UPDATE: 18 OCT 2016
While researching drongos, on 18 Oct. 2016 I discovered two more photos of female Amur Paradise Flycatcher. The photos above were taken 4 July 2009 at Laoshan (32.071265, 118.560699), a site in Nanjing, Jiangsu 290 km inland from Shanghai. Note again in this Amur the contrast between bluish-black head and bluish-grey breast, the poorly defined border between the bluish-grey breast and the whitish belly, the lack of rufous coloration on the flanks, and the rufous-brown upperparts and tail, obviously brighter than in Japanese Paradise Flycatcher.
Special thanks to Kai Pflug, who collaborated with me on this post, and without whose photos this post would not have been possible. Kai’s images of Amur Paradise Flycatcher, some of which are displayed above, are a valuable record of this poorly known species. I have published dozens of Kai’s photographs on shanghaibirding.com, and in September 2016 I wrote about his work cleaning up the litter at Nanhui. Kai is from Germany and lives in Shanghai. He is an active member of the Shanghai Birding WeChat group.
Brazil, Mark. Birds of East Asia. Princeton University Press. Studied entries on Asian Paradise Flycatcher and Japanese Paradise Flycatcher, p. 302.
del Hoyo, Josep, et al., eds. The Handbook of the Birds of the World. Lynx Edicions. Vol. 11, “Old World Flycatchers to Old World Warblers.” Species accounts for Asian Paradise Flycatcher (p. 289) and Japanese Paradise Flycatcher (p. 290) written by C.W. Moeliker.
Editor’s note: 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.
Last Sat. 24 Sept. 2016 at Nanhui, my object of observation was Pale-legged Leaf Warbler, one of the Big 5 Leaf Warblers in the Shanghai region. In both spring and autumn, Phylloscopus tenellipes passes through Earth’s greatest city in considerable numbers, giving Shanghai birders ample opportunity to study it. A lookalike species, Sakhalin Leaf WarblerP. borealoides, also has been noted in Shanghai.
In this post, I shall outline the near-impossibility of distinguishing Pale-legged Leaf Warbler from Sakhalin Leaf Warbler on anything but song, and I will show you some of the traits of “Pale-Sak” that set this species pair apart from other leaf warblers. I also have a roundup of the other birds I noted this past Saturday.
ONLY SONG CAN SAFELY SEPARATE PALE-LEGGED FROM SAKHALIN
Pale-legged Leaf Warbler is safely separable from Sakhalin Leaf Warbler only by song. 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” (1). Mark Brazil says field separation of Pale-Sak is “uncertain,” and he warns readers to “beware light conditions” (2). P. 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” (3). 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 last 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 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.
Note that, according to Brazil, the call of Pale-Sak only can separate the pair from other species. It cannot be used to separate Pale-legged from Sakhalin. The tink of Pale-legged, Brazil writes, “is probably indistinguishable from Sakhalin Leaf” (2).
UPDATE: 19 OCT. 2016
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 written 18 Oct. 2016, 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.”
ROUNDUP FOR SATURDAY 24 SEPT. 2016
Stimulating discussions about leaf warblers enlivened the lulls on a day in which my wife Elaine Du and I once again partnered with veteran British birder Michael Grunwell. We noted 69 species, starting at the sod farm south of Pudong airport then spending the rest of the day at Nanhui. We reunited briefly with the Sino-German birding duo of Xueping and Stephan Popp, and we met Dutch birder Benjamin Muis. Highlights:
Juvenile spotted on mudflats at high tide. A far-northern, trans-Eurasian breeder, Philomachus pugnax is a scarce passage migrant in Shanghai. Amid the greenshanks and godwits, the Ruff stood out with its buff-washed head and scaly upperparts. Juvenile Ruff resembles Buff-breasted Sandpiper, a much smaller American bird that we quickly ruled out.
1 juv. Earlier mis’ID as Peregrine Falcon; corrected 3 Oct. 2016. Thanks to the commenters below for pointing out the error.
A week ago ca. 2500, on Saturday only 10. Coastal birding is a parade of change, especially in migration season.
Other goodies: Eurasian Wryneck 2, Japanese Paradise Flycatcher 6, Amur Paradise Flycatcher 1, Richard’s Pipit 5, White’s Thrush 5 first-of-season, Rufous-tailed Robin 1 first-of-season. We introduced Benjamin to Reed Parrotbill calling unseen from the reeds below, we had a strong count of 16 Blue-and-white Flycatcher, and we noted two endangered species: Far Eastern Curlew and Yellow-breasted Bunting.
Eurasian Wigeon Anas penelope 5
Eurasian Teal A. crecca ca. 300
Common Pheasant Phasianus colchicus 5
Little Grebe Tachybaptus ruficollis 40
Great Crested Grebe Podiceps cristatus 1
Yellow Bittern Ixobrychus sinensis 1
Grey Heron Ardea cinerea 30
Great Egret A. alba 13
Intermediate Egret A. intermedia 2
Little Egret Egretta garzetta 12
Eastern Cattle Egret Bubulcus coromandus 20
Chinese Pond Heron Ardeola bacchus 4
Black-crowned Night Heron Nycticorax nycticorax 10
Common Moorhen Gallinula chloropus 2
Eurasian Coot Fulica atra 8
Black-winged Stilt Himantopus himantopus 5
Pied Avocet Recurvirostra avosetta 5
Grey Plover Pluvialis squatarola 1
Kentish Plover Charadrius alexandrinus 100
Far Eastern Curlew Numenius madagascariensis 1
Black-tailed Godwit Limosa limosa melanuroides 14
Red-necked Stint Calidris ruficollis 20
Dunlin C. alpina 30
Green Sandpiper Tringa ochropus 4
Spotted Redshank T. erythropus 4
Common Greenshank T. nebularia 30
Marsh Sandpiper T. stagnatilis 8
Common Redshank T. totanus 5
Ruff Philomachus pugnax 1
White-winged Tern Chlidonias leucopterus 10
Whiskered Tern C. hybrida 5
Feral Pigeon (Rock Dove) Columba livia 5
Spotted Dove Streptopelia chinensis 6 Cuculus sp. 4
Common Kingfisher Alcedo atthis 1
Eurasian Wryneck Jynx torquilla 2
Eurasian Hobby Falco subbuteo 1 juv.
Black-winged Cuckooshrike Coracina melaschistos 1
Brown Shrike Lanius cristatus 3
Long-tailed Shrike L. schach 28
Black-naped Oriole Oriolus chinensis 1
Black Drongo Dicrurus macrocercus 1
Japanese Paradise Flycatcher Terpsiphone atrocaudata 6
Amur Paradise Flycatcher T. incei 1
Oriental Skylark Alauda gulgula 3
Sand/Pale Martin Riparia riparia/diluta 1
Barn Swallow Hirundo rustica ca. 200
Light-vented Bulbul Pycnonotus sinensis 4
Yellow-browed Warbler Phylloscopus inornatus 1
Pale-legged/Sakhalin Leaf Warbler P. tenellipes/borealoides 10
Eastern Crowned Warbler P. coronatus 5
Zitting Cisticola Cisticola juncidis 1
Plain Prinia Prinia inornata 2
Reed Parrotbill Paradoxornis heudei 1
Crested Myna Acridotheres cristatellus 2
White’s Thrush Zoothera aurea 5
Dark-sided Flycatcher Muscicapa sibirica 1
Asian Brown Flycatcher M. dauurica 8
Blue-and-white Flycatcher Cyanoptila cyanomelana 16
Rufous-tailed Robin Larvivora sibilans 1
Blue Rock Thrush Monticola solitarius philippensis 1
Eurasian Tree Sparrow Passer montanus 100
Eastern Yellow Wagtail Motacilla tschutschensis 4
White Wagtail M. alba 4
Richard’s Pipit Anthus richardi 1
Yellow-breasted Bunting Emberiza aureola 1
(1) Alström, Per. 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.
(3) del Hoyo, Josep, et al., eds. The Handbook of the Birds of the World. Lynx Edicions. Vol. 11, “Old World Flycatchers to Old World Warblers,” species accounts for Pale-legged Leaf Warbler (p. 663) and Sakhalin Leaf Warbler (p. 664) written by P. Clement.