Featured image: Craig Brelsford (L), Brelsford’s partner Jon Gallagher, and Per Alström (R), in the Dulong Gorge in northwestern Yunnan. The insets show Himalayan ThrushZoothera salimalii, which Alström was there studying, and photos of which Brelsford later acquired. Alström’s research led to the recognition of Himalayan Thrush as a species, and Brelsford’s photos were used in Alström’s paper and published in news outlets worldwide. (Huáng Xiǎo Ān [黄小安])
With more and more birders operating in Shanghai, more and more vagrant birds are bound to be discovered. One possibility is Blyth’s PipitAnthus godlewskii (photo above, L), a species similar to our familiar Richard’s Pipit A. richardi (R). Blyth’s breeds mainly in Mongolia, occurs on passage in central China, and winters mainly in India, so any records here would be of extralimitals. Let’s examine here how to separate the two pipits.
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:
Richard’s Pipit, flight call, Dishui Lake, Shanghai, February (00:01; 852 KB)
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!
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.”
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.
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.
Bottom line: In Shanghai, any Pale–Sak one sees is probablyPale-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.
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.
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.
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: 26 Sep 2020)
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)