Nial Moores, Birds Korea, October thirty first 2023.
(All pictures copyright of Nial Moores / Birds Korea and never for use or re-posted with out permission).
Baengnyeong is an enormous and densely vegetated island – far too giant to cowl correctly in a day. The island’s geography, nevertheless, does assist to pay attention birds and a lot of the higher patches of habitat are apparent – wetlands or taller timber or open fields within the southwest or northeast the place birds are inclined to arrive or depart; or larger hill peaks utilized by hovering birds. Another productive habitat patches look quite much less promising in satellite tv for pc pictures. One such space is a valley on the sting of Jinchon within the northeast. Though the valley is 600m or extra inland and liable to disturbance, it is kind of aligned north-south, with rice-fields and fallow fields edged by bushes and banks of timber. Most mornings in spring or autumn, there’s excessive turnover via this a part of the island – and highlights on this valley over time have included Inexperienced-backed Flycatcher Ficedula elisae, two Asian Koel Eudynamys scolopaceus collectively and Korea’s first (and up to now solely) Buff-throated Warbler Phylloscopus subaffinis.
Within the early hours of October 19th, a low stress system crossed the Yellow Sea, and winds swung to the northwest. These winds strengthened considerably by the 20th, gusting as much as 50 km/hr on the island with an airflow reaching deep to the west and northwest, earlier than beginning to weaken throughout the afternoon of the 21st.
At daybreak on 22nd, circumstances had been clear and calm, and lots of birds had been vocalizing within the valley together with a late singing Gray-backed Thrush Turdus hortulorum and rarer nonetheless, a Crimson-breasted Flycatcher Ficedula parva. Ready for higher views of the flycatcher, I heard a collection of unfamiliar deep, well-spaced “Chak” notes coming from a close-by space of tangled bushes and timber – related in construction to the standard “bamboo-snapping” name of Japanese Bush Warbler Horornis diphone, however louder, sharper and fewer slurred, extra like an Oriental Reed Warbler Acrocephalus orientalis however with none of those well-spaced calls working into one another.
Preliminary, temporary views of the chook within the dappled shade of early morning revealed a plain trying, unstreaked, medium-sized, brownish warbler, with a long-looking tail and invoice and a strikingly plain-looking face. Though views had been very temporary, the tail sides seemed whiteish, suggesting Booted Warbler Iduna caligata 쇠덤불개개비. The chook then disappeared into deeper cowl, with the calls regularly turning into an increasing number of distant.
A really lengthy twenty minutes handed, earlier than the calls began once more shut by, with the chook foraging, principally hid, each in low tangles and in addition 2-3 meters up within the decrease branches of timber.
Higher views of the chook over the following three hours revealed that the suggestion of white within the outer tail feathers was extra seemingly an phantasm brought on by some put on or bleaching mixed with lengthy (and fairly dishevelled), pale undertail coverts wrapping up across the tail sides. These lengthy undertail coverts narrowed the search down additional: this was certainly an Acrocephalus reed warbler.
The dearth of a darker forehead shortly dominated out species like Black-browed Acrocephalus bistrigiceps and Manchurian Reed A. tangorum; and ‘scope views instructed apparent emarginations –asymmetrical narrowing of the outer webs of the first feathers – which had been confirmed on p3 and p4 within the pictures.
These emarginations mixed with the dark-looking uninteresting plumage, lack of pale tricks to the primaries, comparatively quick main projection, and name appeared to rule out still-unrecorded species like Eurasian Reed A. scirpaceus and Marsh Warblers A. palustris, and left solely two actual choices: Blyth’s Reed Warbler A. dumetorum and Blunt-winged Warbler, A. concinens, a quite poorly-known species but to be recorded in Korea.
Primarily based on some recordings of Blyth’s Reed and some of Blunt-winged Warblers on Xeno-canto, and the lengthy look to the invoice, the more than likely candidate was Blyth’s Reed Warbler. It is a species which is already included on the Birds Korea guidelines on the idea of a chook photographed in woodland on Chilbal Islet in Shinan County by Park Chong Uk and Kim Yang Mo on August 30th 2018. Their identification was primarily based on a assessment of pictures by Peter Kennerley and Richard Porter – which oddly didn’t embrace any reference to Blunt-winged Warbler. Calls of the Chilbal chook had been both not heard or weren’t recorded; and the relative main lengths appear a bit of difficult to interpret within the pictures, although the long-looking invoice and pretty sturdy facial sample had been thought of to be strongly indicative of Blyth’s Reed Warbler.
The query remained: was it doable to confidently exclude Blunt-winged Warbler, in order that the Baengnyeong chook might be recognized as Blyth’s Reed Warbler? I shared a number of pictures with Professor Phil Spherical in Thailand, an professional authority on Blunt-winged Warbler and different Acrocephalus. He very kindly and helpfully confirmed that, to his eyes, the pictures “tick all of the packing containers” for Blyth’s Reed Warbler, with the tip of “p2 roughly = p6”; with p1 “virtually actually shorter than the longest main coverts”; and with a darkish loral spot. As well as, he summarized the principle variations from Blunt-winged as: (1) often longer p1 in Blunt-winged than instructed within the pictures of the Baaengnyeong chook; (2) a lot shorter p2 in Blunt-winged, with p2 often = p8 or p9; (3) plainer face in Blunt-winged; and (4) shorter invoice in Blunt-winged. Now we all know what to search for!
Habitat and behavior additionally appeared to lend (weak further) help to this identification too – as Blunt-winged is extra typically related to wetland and grassland. The Baengnyeong chook might simply have moved into extra wetland kind habitat, however as an alternative foraged actively in amongst timber and bushes – behaviour apparently typically proven by Blyth’s Reed Warbler.
Reference to Kennerley & Pearson’s “Reed and Bush Warblers” (printed in 2010 by Helm) allow ageing as a chook born this yr, because the irides are grey-brown.
Due to potential curiosity within the file, on October Twenty second I shared a picture of the chook labelled as Blyth’s Reed Warbler on Fb and in addition listed the file with a picture on eBird. Nevertheless, maybe unsurprisingly (contemplating simply how plain-looking this chook was!) no-one requested any particulars of the precise location – though the chook remained in the identical timber and bushes not less than till October 26th once I left the island.
To summarise: that is the second nationwide file of Blyth’s Reed Warbler within the Republic of Korea. The species was recognized on the idea of the decision (recorded on an ordinary cellphone); on particulars of the pinnacle sample; and particularly via particulars of the primaries, seen in digiscoped pictures. Assist for the identification was supplied additional by the habitat: few reed warbler species actively desire to forage in woodland and woodland edge.
Lastly, my thanks as soon as extra to Prof. Phil Spherical; and in addition to Dr Park Jong-Gil for sharing particulars of the 2018 file (and extra fascinating dialogue on warbler ID!) .
