Dr Nial Moores, Birds Korea, August twenty sixth 2024
The simplified 2024 Birds Korea Guidelines consists of Hartert’s Leaf Warbler Phylloscopus goodsoni for the primary time. The species is included in a Assessment Class (i.e., not within the checklist of adequately-documented species) on the idea of a leaf warbler, both Hartert’s or Claudia’s P. claudiae, documented by Dr Kim Sung-Hyun, Kim Jeong Received, Kang Chang-Received and Kang Hee-Man on Marado, Jeju, on April 4th 2024.
The next publish goals to supply background data after which to elicit professional opinion on this chook, to assist decide whether or not or not the chook on Jeju will be recognized to species (each as a part of work for Birds Korea and likewise as reviewers for eBird). Please tell us your ideas…
- Background
(1) Blyth’s Leaf Warbler Phylloscopus reguloides was break up solely 20 or so years in the past into three very similar-looking species: (i) Blyth’s Leaf Warbler Phylloscopus reguloides sensu stricto, with three subspecies, which all appear impossible to happen in Korea as a result of their breeding ranges run west-east alongside and to the south of the southern fringe of a lot of the Himalayan Massif – ensuing within the Korean identify of 히말라야산솔새 (“Himalayan Japanese Topped Warbler”); (ii) Hartert’s Leaf Warbler Phylloscopus goodsoni which has two migratory subspecies each of which attain southern China (Fig. 3)- the yellower nominate to the southwest, and the whiter-below fokiensis to the east and northeast (a species from time to time reaching as near Korea as Shanghai); and (iii) Claudia’s Leaf Warbler Phylloscopus claudiae, a longer-range migrant (Fig. 4) which breeds to the west and north-west of Korea, with substantial numbers reaching as far north as Beijing to breed. Primarily based on Claudia Leaf’s frequent Nuthatch-like foraging behaviour and its northerly breeding vary, this resulted within the coining by Birds Korea of the Korean identify of 북방동고비솔새 (“Northern-distributed Nuthatch-like leaf warbler”).
(2) Though comparatively simple to determine to species-pair if seen or heard in a lot of China or anyplace in Korea, separation of Hartert’s from Claudia’s seems from out there literature to be a significant ID problem. This problem is more likely to be significantly compounded e.g., by older remedy of them each as subspecies of Blyth’s; particular person variation and put on; the shortage of appropriately detailed literature, at the least in English; and the potential for misidentified people being posted on-line.
Most English-language accounts and pictures seem to counsel merely that Hartert’s look brighter with extra yellow and inexperienced tones than Claudia’s; and del Hoyo et al (2020) in Birds of the World at the moment state, “Till just lately [Claudia’s] thought-about conspecific with P. reguloides [Blyth’s] and P. goodsoni [Hartert’s] however separated on foundation of deep molecular divergence and vocal variations. This association provisionally accepted right here pending additional proof on voice, distribution and habitat, though the taxon at the moment fails to fulfill required standards underneath the scoring system used herein, differing in its whitish vs boring yellowish-white supercilium and underparts; marginally much less white in tail; and comparatively distinctive tune (a easy repeated notice), though a second tune kind is just about inseparable from songs of others (implications unknown).”
In help of the assertion on vocalisations in Birds of the World, the variation in tune varieties offered on Xeno-Canto counsel that – if the identifications have been made accurately – each Claudia’s and Hartert’s present apparent variations of their songs. There additionally appears to substantial variation in calls. Primarily based on recordings on Xeno-Canto, Claudia’s calls appears to differ out from a barely thinner, generally hesitant, “pii-Pit-Tuu” (just like the Socheong chook in 2009: pay attention under) whereas some calls labelled as Hartert’s sound just a little extra explosive initially, earlier than trailing off just a little, “PEE-PIT-chuu”). Both manner, because of the pretty wide-seeming variation, some songs and calls sound clearly completely different from one another whereas others sound confusingly related.
Some leaf warbler species do have two distinctively completely different tune varieties (e.g., Japanese Topped Warbler P. coronatus), nevertheless it appears genuinely extraordinary that Claudia’s and Hartert’s might share the same tune kind or varieties and likewise appear to have overlap of some form in calls. On the very least, you will need to recognise that what are at the moment considered variations of their vocalisations doubtless will increase the potential for misidentification of people each outdoors and even throughout the breeding vary; and that this case has doubtless helped to confuse the event of ID standards primarily based on plumage and construction.
(3) Though brighter Claudia’s and duller Hartert’s presumably have to be left unidentified if silent or giving overlapping vocalisations, on-line photographs (accurately or incorrectly) counsel that birds displaying in depth gray on the pinnacle are recognized / identifiable as Claudia’s (presumably being out of the anticipated plumage vary of Hartert’s); and people displaying in depth yellow on the underparts are recognized / identifiable as Hartert’s (some fokiensis, and maybe most or all nominate goodsoni).
(4) I’ve seen two “grey-shawled”, boring and cold-looking, Nuthatch-like foraging leaf warblers within the ROK that I recognized as Claudia’s: one digiscoped on Socheong Island on April 14th 2009 (Figures 2 and 5-8 under), as a part of a significant arrival together with some “western” migrants (equivalent to Crimson-throated and Black-throated Thrushes); and one, seen solely, on Baengynyeong Island on April 26th 2021. Identification of the primary chook was primarily based on enter from a number of fieldworkers with expertise of those species; and no requests to rethink the file have been despatched to us following posting of photographs at the moment and within the outdated Birds Korea gallery. (Now that data of those warblers has improved, ought to this identification stand, or ought to this too be thought-about as a Claudia’s / Hartert’s ?)
(5) On April 14th 2009, I additionally sound-recorded what I presume(d) to be the decision and tune of a Claudia’s a number of instances over a one-hour interval (most definitely given by the digiscoped Claudia’s, although that chook was by no means really seen in tune, and the tune was coming from an space of tangled bushes about 100m from the place I digiscoped the chook). I additionally briefly heard the decision and 2-3 tune phrases (both Claudia’s or Hartert’s) on Socheong Island on April twenty fifth 2010.
Presumed Claudia’s Leaf Warbler Phylloscopus claudiae: a number of “hesitant” calls and a brief burst of tune, Socheong, Incheon, April 14th © Nial Moores
Again in 2009, there have been only a few sources out there to test songs and calls; and I didn’t obtain a definitive sure or no from a number of specialists (together with Prof. Jochen Martens) once I despatched sound recordsdata solely. Progress of the archive on Xeno-Canto now permits a extra strong comparability. The Socheong chook didn’t give a tune just like (most of? all of?) the recordings of Claudia’s in Hebei to the north of the vary. Nevertheless, the tune does sound just like some people recorded in Hubei Province, towards the south of the breeding vary, e.g., XC807627, XC8075672 and XC8075670. Is that this the second tune kind described in Birds of the World? Is that this song-type or subsong (?) given by all populations or is it often given solely by southern populations or on migration?
(6) Varied on-line accounts and particularly on-line photographs within the Macaulay library (filtered for months March-Could solely, specializing in photographs taken within the respective breeding ranges) counsel that in spring, when plumage is at its most worn and boring, most birds recognized as Hartert’s look somewhat brighter than Claudia’s. Though some regional field-guides (e.g., one protecting Taiwan) counsel that Hartert’s may need a slightly better whole size than Claudia’s (11-12cm in comparison with 10-12 cm), to my eyes Hartert’s in most of the photographs look rather less closely constructed, with maybe a slighter and shorter invoice.
(7) In the identical on-line photographs within the Macaulay library, fokiensis Hartert’s seem to have extra inexperienced within the crown sides, extra yellow within the supercilium, and a stronger, brighter blaze on the closed wing than most Claudia’s, whereas most Claudia’s in March-Could look colder-toned, typically with extra greyish tones on the pinnacle, neck sides and mantle, with most of the greyest birds trying clearly “shawled” (cf 2009 chook on Socheong; and the 2021 chook on Baengnyeong) and even hooded. In a number of the similar photographs, the facial sample additionally seems modestly or strongly weaker in lots of Hartert’s than in Claudia’s, with some Hartert’s having a weaker loral line, a weaker eye-stripe behind the attention with much less filled-in ear coverts, and sometimes greenish somewhat than darkish gray washed crown sides.
(8) In spring, the identical on-line photographs counsel that the leg color of Hartert’s will be paler than typically seen in Claudia’s, which extra typically seems to have darker greyish legs with paler or concolorous toes. Just a few Claudia’s additionally seem to indicate some weak darkish smudge on the decrease mandible, whereas the invoice of Hartert’s extra typically appears somewhat brighter orange on the decrease mandible, with none darkish markings.
(9) Each Claudia’s and Hartert’s present some white or grey-white within the tail (each apparently much less extensively than Blyth’s), which is most obvious on the underside of the tail, and particularly when the tail is unfold. A determine in a pdf by Alstrom (2012) maybe means that Claudia’s may present extra in depth white on the second outermost pair of tail feathers than Hartert’s. Do particulars of white on the tail have any worth as an ID function when attempting to separate Claudia’s and Hartert’s?
(10) Though Claudia’s is believed emigrate considerably better distances than Hartert’s, on-line photographs counsel that Hartert’s and Claudia’s may present (broadly) related major spacing. Are there any helpful variations in wing formulae between them that can be utilized in ID? In that case, what are they?
2. Mara Do, Jeju, April 4th 2024 (documented by Kim Sung-Hyun, Kim Jeong Received, Kang Chang-won and Kang Hee-Man).
(1) A leaf warbler photographed on Mara Do, Jeju, April 4th was initially listed on eBird as a Claudia’s / Hartert’s by Dr Kim Sung-Hyun (https://ebird.org/guidelines/S167191532). Following some professional overview inside Korea, this particular person was then listed in an extended report as Claudia’s. ID as Claudia’s was based totally, it seems, on a comparability of photographs with Blyth’s and on field-guide photographs and texts (e.g., Birds of Taiwan). This warbler was a part of an distinctive arrival which additionally included two Sulphur-breasted Warbler P. ricketti (solely 2-3 earlier nationwide data) and a Ferruginous Flycatcher (scarcely annual nationally) together with small numbers of e.g., Yellow-browed Warblers P. inornatus and a Pallas’s Leaf Warbler P. proregulus. This arrival adopted very stormy circumstances over southern China, which included a number of tornadoes.
(2) Due to the sort sharing of knowledge and pictures by the finders, it has been doable for me to overview seven photographs of this chook: 4 contained in entry 433 of this longer report, and three (Figures 1, 9 and 10) kindly shared individually by Mr Kang Heeman. The report states that no vocalisations have been recorded. The chook moved via low bushes, as nicely hanging the other way up like a Eurasian Nuthatch. This latter foraging behaviour is seemingly proven by each Hartert’s and Claudia’s (and far much less so by Blyth’s). As Blyth’s can successfully be dominated out on behaviour and vary, all photographs present a chook which is clearly both Claudia’s or Hartert’s. Primarily based on a mixture of options, all different species will be safely excluded.
(3) On first seeing a picture of the Marado leaf warbler (shared via Instagram), my persistent impression was that this chook seemed brighter and never fairly as heavy-billed as Claudia’s. May this subsequently be Korea’s first Hartert’s? Assessment of the 4 photographs within the longer report and the three photographs shared individually by Mr Kang Heeman counsel that structural, plumage and naked half options, mixed with the date, certainly appear to suit Hartert’s at the least in addition to or fairly presumably even higher than Claudia’s – although in consideration of the significance of this file and the issue of ID, clearly extra professional enter is required to find out whether or not or not a assured ID to taxon will be made.
(4) The report textual content states that the chook seemed intermediate between a Yellow-browed P. inornatus and an Arctic Warbler P. borealis in construction. To me, the neck appears somewhat brief within the photographs, giving the chook a reasonably neckless look, and making the chook seem fairly small. My impression of Claudia’s is extra like Japanese Topped P. coronatus, with a extra elongated form than proven in lots of photographs of Hartert’s (particularly when foraging).
(5) The report photographs, whereas maybe just a little overexposed (at the least in copy within the report) counsel that the Jeju chook was largely olive-green or moss-green above, with paler, off-white underparts. Figures 1, 9 and 10 as an alternative counsel an clearly bright-looking chook, with inexperienced upperparts. The supercilium and median crown stripe are extremely contrasting. The brow is greenish-grey, and the rest of the median crown stripe is grey-green or maybe gray admixed with green-yellow tones for many of its size, flaring barely and changing into paler on the nape. The crown sides are greenish with a touch of yellow to above the attention and greener barely behind (as proven in lots of photographs of Hartert’s and in somewhat few photographs of Claudia’s); and really darkish solely on the base of the nape. There’s a very slender, contrasting black or darkish edge to the supercilium, with the supercilium trying fairly Pallas’s Leaf Warbler like, in being golden yellow on the supra-lorals and above the attention (just like many Hartert’s however fewer Claudia’s in on-line photographs), and yellowish (or wealthy cream) to the rear. There’s a darkish line on the lores, which peters out towards the invoice base (a function maybe proven extra typically by Hartert’s). The attention-stripe is broader behind the attention, however a lot of the ear coverts are open-looking and streaked with yellow, once more apparently a sample proven by extra Hartert’s than Claudia’s in on-line photographs. The underparts are whiteish, with some faint yellow streaking, together with on the throat, with a stronger yellow wash on the axillaries and underwing coverts (Fig. 10). The mantle and again are inexperienced or moss-green (missing the clearly colder greyer scarf proven by many Claudia’s, at the least in a single picture, although trying greyer on the neck aspect in two of the pictures, as is likely to be anticipated in Claudia’s and advised in only some photographs of Hartert’s). The mantle is kind of concolorous with the upperwing coverts (not like many Claudia’s in spring). The remiges of the closed wing present a really brilliant, contrastingly green-gold blaze (maybe typical of Hartert’s, maybe stronger than anticipated in Claudia’s), as do the upperside of a number of the rectrices. The chook exhibits two yellow-washed wing-bars (not white or whiteish as proven by some Claudia’s), pretty slender on the median and broader on the better coverts.
(6) The report photographs counsel that the decrease mandible is brilliant orange (with no or solely the faintest trace of a darker patch) and the culmen is darker. The legs are brownish or darkish red-brown, with clearly yellower toes. Many photographs of Claudia’s counsel that the legs are sometimes darker than this, maybe particularly in spring.
(7) The close-up picture of the primaries seems to indicate related spacing to on-line photographs of each Claudia’s and Hartert’s.
(8) Report photographs reveal that the upperside of the tail exhibits a slender whiteish or grey-whiteish tip to the outermost pair, with this pale extending alongside the internal fringe of the outermost feather, at the least on the left aspect of the chook. The pale fringe that’s seen seems to be somewhat much less white and fewer in depth than is likely to be anticipated in Claudia’s (primarily based on my interpretation of two photographs in Alstrom 2012). The width of the pale on the tip of the outer pair of tail feathers subsequently appears nearer to that proven by Hartert’s in some on-line photographs (and in Alstrom 2012).
(9) The date of the file is considerably sooner than the three earlier file(s) of Claudia’s / Hartert’s in Korea which have been between April 14th and April 26th. Maybe not sufficient is understood but concerning the migration phenology of those taxa and there are actually too few data in Korea to make use of dates as greater than weak help for any ID. Nevertheless, the chook on Marado was discovered on the identical date as two southern overshoot vagrant species (with their breeding distribution to the south or southwest of Korea) – and never with any vagrant species with an clearly extra western or northwestern distribution It subsequently appears doubtless that these three species have been picked up by the identical climate system kind of from the identical area in a single day on the threerd, to be drifted out over the South China and Yellow Sea – with their first landfall Marado. Of potential curiosity on this regard, vary maps in Birds of the World counsel substantial overlap within the japanese a part of the vary of fokiensis Hartert’s with Sulphur-breasted Warbler and Ferruginous Flycatcher and little overlap with Claudia’s, which has a typically extra westerly distribution.
(10) By early August 2024, there have been 675 eBird data for Claudia’s within the Beijing area. These data present a frequency of inclusion in checklists of 0.1% within the first quarter of April; rising to 1% within the third quarter; and to three.3% within the fourth quarter of April (rising to >7% within the first week of Could). If there is no such thing as a bias attributable to variations in observer exercise, this may counsel that the principle arrival at a latitude just like or to the north of Korea is late April. Additional south, there are a complete of 27 data of Claudia’s within the Shanghai area (if accurately recognized), with the earliest within the first week of April, and the height of data within the third quarter of April, once more broadly matching the temporal sample of data in Beijing (and of the three earlier data in Korea). Within the case of Hartert’s, there aren’t any data on eBird as far north as Shandong or Beijing and there are solely 5 data in Shanghai (3 -4 in spring, with the “peak” in mid-April). Nevertheless, there are 24 data additional west in Anhui (at a kind of related latitude to Jeju), with the primary arrivals to forest breeding areas there as early as late March. It’s subsequently doable to conclude that primarily based on current understanding, the date of the chook on Marado is a good match for an overshooting Hartert’s; and a somewhat poor match for an overshooting Claudia’s.
In conclusion, within the absence of higher data and with out professional enter from skilled observers, it appears unwise merely to rule out Hartert’s Leaf Warbler.
Itemizing all data of this species pair as Claudia’s may nicely discourage birders from totally documenting the subsequent related particular person in Korea; and regionally may additionally lead to some confusion over temporal patterns of incidence of each taxa.
As a substitute, we’ve made the choice to hunt the professional opinions of skilled observers. Can silent people of Claudia’s and Hartert’s be safely recognized? How? Can “overlapping” vocalisations be used?
We particularly welcome knowledgeable feedback on the 2009 file; and on the 2024 Marado file.
Thanks prematurely for all and any feedback that you just may have the ability to present!
Important sources of Info for this publish embody:
- del Hoyo, J., N. Collar, and D. A. Christie. 2020. Claudia’s Leaf Warbler (Phylloscopus claudiae), model 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.clalew1.01
- Macaulay Library, dozens of photographs of each Hartert’s and Claudia’s Leaf Warblers in months March-Could
- Per Alström pdf of Leaf Warbler identification (2012): Identification of Phylloscopus & Seicercus warblers in China
- “Ayuwat Weblog” Publish identification of Blyth’s, White-tailed and Claudia’s leaf Warbler in Thailand
