Identification of Phylloscopus & Seicercus warblers in China Per Alström
Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing and Swedish Species Information Centre, Swedish University of Agricultural Sciences, Uppsala, Sweden
14 Nov 2012 Taxonomic history
Cheng Tso-hsin (1987): 24 species Dickinson (2003): 43 species Zheng Guangmei (2011): 45 species Gill & Donsker (2012): 51 species Taxonomic history New species: • Hainan Leaf Warbler Phylloscopus hainanus Olsson, Alström & Colston, 1993 • Alström’s Warbler Seicercus soror Alström & Olsson, 1999 • Martens’s Warbler Seicercus omeiensis Martens, Sun & Päckert, 1999 • Emei Leaf Warbler Phylloscopus emeiensis Alström & Olsson, 1995 • Alpine Leaf Warbler Phylloscopus occisinensis Martens, Sun & Päckert, 2008 • Limestone Leaf Warbler Phylloscopus calciatilis Alström, Davidson, Duckworth, Eames, Le, Nguyen, Olsson, Robson & Timmins, 2009 Taxonomic history
Taxonomic “splits” – 19 “new” species: • Arctic Warbler Phylloscopus borealis 1 3 species • Blyth’s Leaf Warbler Phylloscopus reguloides 1 3 species • Greenish Warbler Phylloscopus trochiloides 1 2 species • Pale-legged Leaf Warbler Phylloscopus tenellipes 1 2 species • Pallas’s Leaf Warbler Phylloscopus proregulus 1 5 species • Tickell’s Leaf Warbler Phylloscopus affinis 1 3 species (1 new) • Yellow-browed Warbler Phylloscopus inornatus 1 2 species • White-tailed Leaf Warbler Phylloscopus davisoni 1 2 species • Golden-spectacled Warbler Seicercus burkii 1 6 species Problems • Small • Active, constantly on the move – often hard to see well • Wear affects e.g. strength of wing-bars and colours; colours vary depending on light conditions • Some species very similar Solutions • Carefully study as many characters as possible • Songs and calls usually diagnostic Plumage topography
median crown-stripe (pale)
lateral crown-stripe (dark) tertials (3) rump (here pale) lores / loral stripe supercilium (pale) eye-stripe (dark) median coverts alula greater coverts primaries
secondaries
Phylloscopus kansuensis James Eaton supercilium (pale) crown
forehead mantle tertials (3)
throat primary projection ear-coverts
breast flanks secondaries undertail-coverts belly wing-bars (pale)
Phylloscopus kansuensis James Eaton 1. Pale wingbars: yes/no?
2. If yes: size ”large”/small? 3. Focus on crown pattern (dark + pale stripes? stripes more distinct at rear?); pale tips to tertials?; dark markings on wings?; pale rump?; white in tail?
Photos: Göran Ekström “Large” no pale wingbars, no or little yellow in plumage Radde’s Yellow- Warbler streaked P. schwarzi Warbler P. armandii
Göran Ekström Göran Ekström
Dusky Smoky Warbler Warbler P. fuscatus P. fuligiventer fuscatus weigoldi
Göran Ekström James Eaton Mountain Chiffchaff Common Chiffchaff Willow Warbler
P. sindianus Björn Johansson P. collybita Göran Ekström P. trochilus Göran Ekström “Large”, no pale wingbars, distinct yellow on supercilium/ear-coverts/underparts
Wood Warbler Grey-hooded Warbler
Tickell’s Leaf Warbler P. affinis – almost identical to Alpine Göran Ekström P. sibilatrix Göran Ekström P. xanthoschistos
Sulphur-bellied Warbler Alpine Warbler Buff-throated Warbler
P. griseolus Andrew Lassey P. occisinensis James Eaton P. subaffinis Zhou Huaming “Large”, 1–2 pale wingbars, no pale median crown-stripe
Greenish Warbler Two-barred Warbler Greenish Warbler (br: C China) (br: NE China) (br: W China)
Andrew Lassey Zhou Huaming P. (trochiloides) viridanus P. trochiloides obscuratus P. plumbeitarsus Göran Ekström
Sakhalin Leaf Warbler P. borealoides – almost identical to Pale-legged Large-billed Leaf Warbler Pale-legged Warbler Arctic Warbler
P. tenellipes Göran Ekström P. magnirostris Zhou Huaming P. borealis Göran Ekström “Large”, 1-2 pale wingbars, pale median crown-stripe Blyth’s Leaf Warbler Hartert’s Leaf Warbler Claudia’s Leaf Warbler
P. claudiae Zhou Huaming P. reguloides Zhao Chao P. goodsoni fokiensis James Eaton Davison’s Leaf Warbler P. davisoni Emei Leaf Warbler Kloss’s Leaf Warbler Eastern Crowned Warbler
James Eaton P. ogilviegranti ogilviegranti P. emeiensis James Eaton P. coronatus Shen Yue “Large”, 1-2 pale wingbars, strong crown pattern, bright yellow below Hartert’s Warbler Limestone Leaf Warbler
P. calciatilis Jocko Hammar P. goodsoni goodsoni Paul J. Leader
Sulphur-breasted Leaf Warbler P. ricketti – almost identical to Limestone Small, 1–2 pale wingbars, no/faint pale median crown- stripe, no pale rump patch Yellow-browed Warbler Yellow-browed Warbler
(migr., wi.)
P. inornatus Shen Yue P. inornatus Zhou Huaming Hume’s Leaf Warbler Hume’s Leaf Warbler (br: C China) (br: W China)
P. humei mandellii James Eaton P. humei humei Andrew Lassey Small, 1–2 pale wingbars, pale median crown-stripe and pale rump patch
Pallas’s Leaf Warbler Sichuan Leaf Warbler (br: NE China) Gansu Leaf Warbler (br: NC China) (br: C China)
P. proregulus Shen Yue P. kansuensis James Eaton P. forresti Zhou Huaming Buff-barred Warbler Lemon-rumped Warbler P. chloronotus (br: S Xizang)
Ashy-throated Warbler Chinese Leaf Warbler
P. maculipennis James Eaton P. pulcher Zhao Chao P. yunnanensis James Eaton Radde’s Warbler P. schwarzi Yellow-streaked Warbler P. armandii
Göran Ekström
Zhou Huaming Zhou Huaming
Shen Yue Some 1st-winter birds quite yellow below
Per Alström James Eaton
In both, note rather short, heavy bill with curved culmen; supercilium more buffish in front than at rear. P. schwarzi on average stronger bill + proportionately shorter tail. Song + especially calls. Bo Peterson/Beidaihe Bird Observatory Dusky Warbler P. fuscatus
Smoky Warbler P. fuligiventer weigoldi
Zhou Huaming
James Eaton
In both, note thin bill; supercilium Göran Ekström whiter in front than at rear (cf. P. schwarzi, P. armandii). P. fuligiventer weigoldi greyer above, whiter below, on average darker lower mandible + legs.
Note how colours may change with light.
Urban Olsson Alpine Warbler P. occisinensis (formerly P. affinis) Buff-throated Warbler P. subaffinis
Göran Ekström Zhou Huaming P. occisinensis on average more pure yellow hues, more prominent supercilium (esp. anteriorly), more contrastingly patterned ear-coverts, less dark on lower mandible; longer bill + shorter tail. Song + calls.
P. affinis in Xizang. In practice inseparable from P. occisinensis.
Zhou Huaming Zhou Huaming All: Zhou Huaming Greenish Warbler Large-billed Leaf Warbler P. magnirostris Phylloscopus trochiloides obscuratus (br: C China)
Zhou Huaming James Eaton Zhou Huaming
Lower mandible mainly dark with pale pinkish base in Large-billed; diffuse darker tip and more orange-tinged lower mandible in Greenish. Song + call!
Per Alström Per Alström Arctic Warbler Two-barred Warbler Phylloscopus borealis Phylloscopus plumbeitarsus
Bo Peterson/Beidaihe Bird Observatory Göran Ekström Göran Ekström
Bo Peterson/Beidaihe Bird Observatory
Göran Ekström Chu Jian-mei Arctic more drawn-out shape; shorter, narrower, less clearcut wingbars; on average narrower supercilium, more contrastingly patterned bill, paler legs. Song + call!
Tang Jia-lin Shen Yue Arctic Warbler Pale-legged Leaf Warbler Two-barred Warbler Phylloscopus borealis Phylloscopus tenellipes Phylloscopus plumbeitarsus
Göran Ekström Göran Ekström Göran Ekström
Göran Ekström
Pale-legged: wing-bars variable, 0–2, usually at least 1; Sakhalin Leaf Warbler P. contrastingly greyer crown; borealoides (rare SE China on mainly dark lower mandible, very migration) virtually pale legs; flicks tail downward. indistinguishable from Pale- Song + call! legged except by song. Arctic Warbler P. borealis, Kamchatka Leaf Warbler P. examinandus, Japanese Leaf Warbler P. xanthodryas Very similar appearances, different songs + calls.
Phylloscopus borealis Magadan, Russia, Phylloscopus xanthodryas Iwate, Phylloscopus examinandus Hokkaido, 3 July 2007. Takema Saitoh. Honshu, Japan, 29 July 2004. Takema Japan, 16 July 2004. Takema Saitoh. Saitoh. On average more yellowish below than two others Nordsångare borealis songs borealis/kennicotti calls
examinandus
xanthodryas
Alström et al. submitted Eastern Crowned Warbler P. coronatus Claudia’s leaf Warbler P. claudiae
Wingbars + crown pattern (crown-stripes more black/ white at rear in Blyth’s). Song + call (Crowned rarely calls)!
All: Per Alström Claudia’s leaf Warbler P. claudiae: Sichuan to Hebei Hartert’s Leaf Warbler P. goodsoni: Guangdong to Fujian
Kloss’s Leaf Warbler P. ogilviegranti: Shaanxi, Sichuan, Fujian
Blyth’s Leaf Warbler P. reguloides: Xizang, Yunnan (to SE Asia)
Davison’s Leaf Warbler P. davisoni: Yunnan (to SE Asia)
Maps from Handbook of the Birds of the World (del Hoyo et al. 2006. Lynx Edicions) Claudia’s Warbler P. claudiae Kloss’s Warbler P. ogilviegranti disturbans
All: Per Alström Kloss’s smaller, more yellow on supercilium All: Per Alström P. claudiae P. o. disturbans + ear-coverts; sometimes dark tip to lower mandible; slight differences outer tail-feathers. Song. Wing-flicking in Zhou Huaming Urban Olsson Claudia’s (breeding). Hartert’s Warbler P. goodsoni fokiensis Kloss’s Warbler P. ogilviegranti ogilviegranti
Hartert’s/Blyth’s larger, less yellow than Kloss’s/Davison’s; songs. Former pair very similar. Kloss’s more yellow, less white on outer tail-feathers than Davison’s (only visible in hand).
Blyth’s Leaf Warbler P. reguloides ticehursti Davison’s Leaf Warbler P. davisoni
All photos: Urban Olsson Emei Leaf Warbler P. emeiensis Hainan Leaf Warbler P. hainanus
Urban Olsson
Per Alström Both: Urban Olsson Claudia’s Leaf Warbler
Emei less distinct crown-pattern than Claudia’s. Song + calls! Per Alström Per Alström Limestone Leaf Warbler Sulphur-breasted Warbler Phylloscopus calciatilis Phylloscopus ricketti
Urban Olsson Ulf Johansson
Jocko Hammar Yellow-browed Warbler P. inornatus Hume’s Leaf Warbler P. humei P. h. humei: W China Hume’s duller when fresh, anterior wing-bar indistinct (Yellow- browed similar
Shen Yue when worn); lower mandible + Shen Yue legs on average darker in P. h. mandellii: C China Hume’s. Song + calls!
Shen Yue
Göran Ekström
Shen Yue Pallas’s Leaf Warbler complex
James Eaton forresti Pallas’s Leaf Warbler P. proregulus Gansu Leaf Warbler P. kansuensis
Shen Yue James Eaton Pallas’s most brightly coloured, especially on supercilium. Gansu & Sichuan extremely similar, on average paler lower mandible + legs in former. Chinese less distinct pale median crown-stripe (esp. anteriorly) + dark eye-stripe; lacks dark bar on bases of secondaries. In all, song + call! Sichuan Leaf Warbler P. forresti Chinese Leaf Warbler P. yunnanensis
James Eaton James Eaton Buff-barred Warbler P. pulcher Ashy-throated Warbler P. maculipennis Buff-barred overall dull, usually buffish wing-bar, slender dark bill; Ashy- throated grey/white head + breast, pale
Zhou Huaming yellow rest of underparts. Song!
Shen Yue Per Alström
Per Alström All: Zhou Huaming “Golden-spectacled Warblers” Himalayas
S. burkii more contrasting crown pattern than S. whistleri; 2 white outer tail-f. vs. 3 in S. whistleri; eye-ring usually thinly broken at rear. In both, less grey on crown than in Chinese species. Seicercus burkii Seicercus whistleri
China S. valentini & S. omeiensis Seicercus omeiensis generally not distinguishable by plumage, but crown pattern on average more contrasting in latter.
All best distinguishable by song + calls! Seicercus valentini
Seicercus tephrocephalus S. soror dullest crown pattern; proportionately large bill + short tail. S. tephrocephalus most contrasting crown pattern; eye-ring usually thinly broken at rear. Seicercus soror
Painting by Ian Lewington, from Alström & Olsson (1999), slightly modified digitally by Anders Rådén 548 I? Alstrom & U. Olsson
recorded by PA., except for burkii from Nepal, which does not quite match that of groups 2 and 3). Group 7 was recorded by Jochen Martens. White-spectacled is mainly characterized by the small amount of white Warbler Seicercus ufiinis was included in the playback on its outer tail-feathers (no overlap with groups 2,3, tests because of its similarity with especially tephro- 5, 8 and 9 and only a marginal overlap with groups 1, cephalus. 4 and 6 on R5 and with groups 4, 5 and 6 on R6; note, however, that in the length of the white wedges in rela- tion to tail length, there is a slight overlap with all Altitudinal distribution except group 2). For details, see Table 1 and Figures 4 In most places, we estimated the altitude by using and 5. known reference points in the vicinity (e.g. on Emei There are more or less pronounced differences in Shan there are several temples of known altitude). In structure between these groups (Tables 2 & 3, Figs 6 & Golden-spectacled Warbler 549 Shaanxi province, China, in India and in Vietnam, we 7). The most striking differences are that groups 1 and measured the altitude with a Casio alt-6000 altimeter 7 are proportionately shorter-tailed (measured as watch. The altitudinal distribution was recorded tail/wing ratio) and larger-billed (measured as bill mainly along roads and trails. In most places there were length x bill widthhail length) than the others. Groups only one or two roads or trails running from the 4 and 5 are smaller than the others, though with rela- bottom to the top of the mountains, and few or no side tively large bills, and group 5 has proportionately the 0.90 1u I c trails. Accordingly, in these places the altitudinal distri- longest tail of any group. See Table 2 and Figures 6 and 5 ’6 0) bution war recorded from a very narrow transect. 7 for details. On wing 0formula, group 7 differs from - 0.85 We also noted altitudes given on labels of specimens. groups 6 and 8 particularly in its shorter P10 and indis- 6, .-C All of the values given under Results are translated tinct emargination on P4 (Table 3). I from feet to the nearest 10 m. It should be noted that the groupsO thatou differ mostn 5 0.80 I prominently in plumage and structure from each other c0) -0 ._- @ 0.75 RESULTS Group 2 whistler; / a, B W N T4T5T6OX S V L Morphology Group 1 -Group 3 Oko S. burkiiburkii S. nemoraliswhistleri 0.70 1 , common, .-- Based on morphology, the birds were separated into B W N T4T5T6 S V L nine groups. The main plumage differences (Table 1, rf451b Group Figs 4 & 5, Plate I) between these groups are in the head and tail patterns. Groups 1 and 4/5/6 differ from Figure 6. Box plot of tail-length/wing-length in different taxa. B, each other chiefly in the colour of the median crown- Group 1 burkii; W, group 2 whistleri; N, group 3 nemoralis; T4, stripe and sides of the crown below the dark lateral group 4 tephrocephalus from Yunnan (China) and northeast stripes (mainly green in the former, as opposed to grey Burma; T5, group 5 tephrocephalus from northeast India and in the lattcr three). Both stand out from the others by rare west Burma; T6, group 6 tephrocephalus from Sichuan (China); R6 R5 R6 R5 R4 S, group 7 soroc V, group 8 valentini; L, grouprare 9 latouchei. Same their more contrasting crown patterns. Groups 4, 5 and individuals as in Table 2 plus 4 unsexed burkii (group 1). 6 are basically similar to each other except for the 2o 3 patterns of the outer rectrices (notably R4 in group 5). Groups 2 and 3 differ from each other mainly in the l5 R4, the description must refer to group 1, since we crown pattern (especially the pigmentation of the dark 101, have not found any specimens of group 2 or group 3 0 W N T4T5T6 S V L lateral crown-stripes), and the same is true for groups with only two white outer rectrices and only these 8 and 9. The former two groups (2 and 3) are distin- rare Group three groups occur in the Himalayas (cf. Fig. 8). guished from the latter two (8 and 9) chiefly by the Cryptolopha auricapilla Swainson, 1837, was R6 R5 Figure 5. BoxR6 plotR5 of lengthR6 of whiteR5 wedgeR6 (inR5 mm) on R5 (a) colour of the median crown-stripe and sides of the Golden-spectacled Warbler 549 described from ‘India’. The type of auricapilla was and R6 (b) in different taxa. B, Group 1 burkii; W, group 2 crown below the dark lateral stripes (mainly green in S. tephro- S. omei- S. soror S. valen- Group whistleri;5 N,Group group 6 3 nemoralis;Group 7 T4, groupGroup 4 8tephrocephalus originally in the Linnaean Society’s Museum, London, the former, as opposed to grey in the latter; analogous cephalus ensis soror valentinitini S. omeiensis S. valentini S. soror tephrocephalusfrom Yunnan (China) and northeast Burma; T5, group 5 tephro- to the diffcrences between groups 1 and 4/5/6), and in cephalus from northeast India and west Group Burma; 9 T6, group 6 1.50 the pattern of R4 (showing much white in the former, tephrocephalusfrom Sichuan (China); S, grouplatouchei 7 soroc V, group while lacking white in the latter). The extensively 8 valentini; L, group 9 latouchei. Same individuals as in Table 2 Figure0.90 4. Outer tail-feathers. Drawing: Per Alstrorn. *50% (n= 1u I plus 4 unsexed burkii (group 1). white R4c in groups 2 and 3 is a feature otherwise 10) S. tephrocephalus from western Burmdnortheast India 5 1.30 found only’6 in some individuals in group 5 (a few birds (group0) 5) lack white on R4. #Most S. burkii (group 1) lack white 1 0 0 0.85 .-s -I- in group I also show white on R4, although the pattern on- R4 (see Table 1). 4 1.20 6, have sympatric breeding distributions (see Distri- ._- .-C n bution, below, and Fig. S), while the ones which are 0 1.10 O oun 5I 0.80 I .-> @ 1999 British Ornithologists' Union, Ibis, 141, 545-568 most similar are allopatric. -m c0) 5 1.00 -0 [r ._- 0.90 @ 0.75 Nomenclatural review Relative size bill 0.80 B W N T4T5T6OX S V L a, - Sylvia burkii Burton, 1836, Okowas described from ‘the 0.70 , , , , , , ~ ~ 0.70 1 Himalayas’, (type locality restricted by Ticehurst, .-- 1925 1 tail tail length / wing length B W N T4T5T6 S V L toB Siklum).W TheN typeT4T5T6 of burkii was Soriginally V depositedL b w w t t o s v v rf451b b w w t t o s v v Group in the Museum of theGroup Army Medical Department, Chatham, UK, but the fate of this collection is Figure 7. Box plot of relative bill size (bill-length x bill-width/tail- Figure 6.unknown, Box plot of andtail-length/wing-length it seems likely that in different the type taxa. has B, either length) in different taxa. B, Group 1 burkii; W, group 2 whistleri; Group 1 decayedburkii; W, orgroup been 2 destroyedwhistleri; N, (Robert group 3 nemoralis;Prys-Jones T4, in litt.). N, group 3 nemoralis; T4, group 4 tephrocephalus from Yunnan group 4 tephrocephalus from Yunnan (China) and northeast The type description states that the tail is brown (China) and northeast Burma; T5, group 5 tephrocephalusfrom Burma; T5, group 5 tephrocephalus from northeast India and northeast India and west Burma; T6, group 6 tephrocephalus west Burma;except T6, forgroup white 6 tephrocephalus inner webs to from the Sichuan two outer (China); rectrices from Sichuan (China); S, group 7 soror; V, group 8 valentini; S, group 7(R5-R6). soroc V, groupProvided 8 valentini; that L,all group of the 9 latouchei. tail-feathers Same were L, group 9 latouchei. Same individuals as in Table 2 plus 4 individualspresent, as in Table and 2that plus Burton 4 unsexed did burkiinot overlook (group 1). any white on unsexed burkii (group 1). 2o 3 R4, the description must refer to group 1, since we l5 @ 1999 British Ornithologists’ Union, Ibis, 141, 545-568 101, have not found any specimens of group 2 or group 3 0 W N T4T5T6 S V L with only two white outer rectrices and only these Group three groups occur in the Himalayas (cf. Fig. 8). Cryptolopha auricapilla Swainson, 1837, was Figure 5. Box plot of length of white wedge (in mm) on R5 (a) described from ‘India’. The type of auricapilla was and R6 (b) in different taxa. B, Group 1 burkii; W, group 2 whistleri; N, group 3 nemoralis; T4, group 4 tephrocephalus originally in the Linnaean Society’s Museum, London, from Yunnan (China) and northeast Burma; T5, group 5 tephro- cephalus from northeast India and west Burma; T6, group 6 1.50 tephrocephalusfrom Sichuan (China); S, group 7 soroc V, group 8 valentini; L, group 9 latouchei. Same individuals as in Table 2 plus 4 unsexed burkii (group 1). 1.30 1 0 .-s -I- 4 1.20 have sympatric breeding distributions (see Distri- ._- n bution, below, and Fig. S), while the ones which are 0 1.10 .-> most similar are allopatric. - 5m 1.00 [r 0.90 Nomenclatural review 0.80 Sylvia burkii Burton, 1836, was described from ‘the Himalayas’ (type locality restricted by Ticehurst 1925 0.70 1 , , , , , , ~ ~ B W N T4T5T6 S V L to Siklum). The type of burkii was originally deposited Group in the Museum of the Army Medical Department, Chatham, UK, but the fate of this collection is Figure 7. Box plot of relative bill size (bill-length x bill-width/tail- unknown, and it seems likely that the type has either length) in different taxa. B, Group 1 burkii; W, group 2 whistleri; decayed or been destroyed (Robert Prys-Jones in litt.). N, group 3 nemoralis; T4, group 4 tephrocephalus from Yunnan The type description states that the tail is brown (China) and northeast Burma; T5, group 5 tephrocephalusfrom northeast India and west Burma; T6, group 6 tephrocephalus except for white inner webs to the two outer rectrices from Sichuan (China); S, group 7 soror; V, group 8 valentini; (R5-R6). Provided that all of the tail-feathers were L, group 9 latouchei. Same individuals as in Table 2 plus 4 present, and that Burton did not overlook any white on unsexed burkii (group 1).
@ 1999 British Ornithologists’ Union, Ibis, 141, 545-568 Seicercus valentini ...... no trills; slow, low-pitched
Seicercus soror ......
no trills; higher-pitched than S. valentini
Seicercus omeiensis ......
includes some trills; usually no introductory element to strophe
Seicercus tephrocephalus ......
many trills; short introductory element to strophe Elevations vary from one mountain to another, but general pattern same. S. m a.s.l. omeiensis chiefly in good forest, S. tephrocephalus mainly in degraded 3500 forest and scrub (e.g. along roads). valentini 2500 omeiensis tephrocephalus 1500 soror intermedius 500 Grey-cheeked White-spectacled Bianchi’s Warbler S. valentini Warbler S. poliogenys Warbler S. affinis intermedius
“intermedius” morph
James Eaton Eye-ring broken above James Eaton eye in Grey-cheeked + James Eaton White-spectacled; eye- ring white in former “cognitus” morph: Grey-crowned Warbler (and in nominate no grey on crown S. tephrocephalus White-spectacled; Himalayas); grey ear- coverts, poorly marked lateral crown-stripes in James Eaton Grey-cheeked.
“cognitus” “intermedius” morph morph
Zhang Yongwen Urban Olsson Urban Olsson Thanks Photos/paintings: Chu Jia-mei, James Eaton, Göran Ekström, Jocko Hammar, Björn Johansson, Ulf Johansson, Andrew Lassey, Paul Leader, Ian Lewington, Urban Olsson, Bo Peterson/Beidaihe Bird Observatory, Takema Saitoh, Shen Yue, Tang Jia-lin, Zhang Yongwen, Zhao Chao, Zhou Huaming, Zhou Ming-bo Assistance/translation: Zhu Lei, Liu Yang, Que Pin-jia
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