INTRODUCTION
Knowledge of the status of some of the unstreaked Asian warblers
in the genus Locustella, formerly placed in the otherwise
African genus, Bradypterus, has been confounded by
past uncertainties over the identification of both museum specimens
and field sightings. We document the first recorded observation
of a Spotted Bush Warbler Locustella thoracica in Thailand,
from Chiang Rai Province, on 27 December 2013. This is the only
non-breeding season record of this species away from the north
and north-east of the Indian Subcontinent and northern Myanmar
(del Hoyo et al., 2006), significantly extending its
presumed wintering
range. Nomenclature follows Gill & Donsker (2014).
On 27 December 2013, during a routine mist-net check by WB,
a warbler was found dead in the lowest panel of a mist-net set
during ringing operations at Nam Kham Nature Reserve, Chiang
Saen District, Chiang Rai (20°17' N, 100° 04' E) at
about 10:27 h (Figure 1). On the basis of measurements and photographs
of the specimen immediately after extraction from the net it
was subsequently identified as a Spotted Bush Warbler Locustella
thoracica. The specimen was preserved in 70% alcohol for
deposition in the Natural History Museum, National Science Museum,
Thailand. The record has been accepted by the Bird Records Committee
of the Bird Conservation Society of Thailand (Limparungpatthanakij
et al., 2014).
DESCRIPTION
An unstreaked bush warbler with the typically strongly rounded
tail and long, graduated under tail-coverts of the genus Locustella.
The longest under tail-coverts were longer than the shortest
outermost tail-feathers. Dark brown upperparts; grey-tinged
sides of head and breast. Lower throat and upper breast grey-washed,
with indistinct blackish spots or mottling. Brownish-washed
flanks. Narrow whitish supercilium present but extent not specifically
noted. White chin and throat, centre of lower breast and belly
(Figure 1A). The individual feathers of the under tail-coverts
had dark brown centres and sharply contrasting, narrow, white
tips (broadest white tip 2.4 mm) (Figure 1B). Upper mandible
blackish-grey, lower mandible, pale flesh with slightly dusky
tip; legs pale horn. Wing length (maximum chord) 55 mm; tail
52 mm, bill (to skull) 15.6 mm; tarsus 18.9 mm. Wing strongly
rounded; wing point p 4; p 2 -7.1 mm, falling roughly opposite
the tips of the secondaries; p 3 -1.3 mm; p 5 -1.0 mm; p 6 -1.6
mm, p 7 -3.9 mm; p 8 -5.1 mm; p 9 -5.6 mm; p 10 - 6.4 mm. p
1 (outermost primary) 7.9 mm longer than longest primary covert
(Figure 1C). Projection of primaries beyond tips of tertials
8.4 mm; p 1–p 2 = 17.6 mm; p1 to wing point 24.6 mm. Primaries
3–5 were emarginated. The primaries were numbered ascendantly—from
the outermost inwards. The shortest (outermost) tail-feather
was 27 mm shorter than the longest tail-feather; projection
of the longest tail-feather beyond the longest under tail-covert
was 19 mm.
It was noticeable that the bird had two ages of primaries. The
outermost primaries, pp 1–7, were relatively fresh, having
presumably been renewed earlier in the winter, whereas the innermost
three primaries were old and worn.
IDENTIFICATION
The present individual was identified as a Spotted Bush Warbler
on the basis of its large size (wing 55 mm), long tail which
projected 19 mm beyond the longest under tail-coverts, and the
narrow white edges to the under tail-coverts, following Alstrom
et al. (2008). The similar Baikal Bush Warbler L. davidi
is smaller and shorter tailed, with much broader white edges
to the under tail-coverts, and a less strongly rounded wing.
Baikal Bush Warbler (formerly considered a race, shanensis,
of Spotted Bush Warbler) is a relatively common winter visitor
to (mainly wetland) habitats in northern and central Thailand
(Lekagul & Round, 1991; Round & Loskot, 1995) and a
total of 51 have so far been ringed at Nam Kham. Two previous
records of supposed Spotted Bush Warblers from northern Thailand,
assigned to L. t. przevalskii and L. t. thoracica,
(Deignan 1945) were shown by Dickinson et al. (2000)
to be misidentified Russet Bush Warblers L. mandelli.
The present record is therefore the first undoubted Spotted
Bush Warbler for Thailand where, as with Baikal Bush Warbler,
it is presumed to be a winter visitor. The Spotted Bush Warbler
breeds from East and Central Himalayas, north and east to Central
China, at elevations from 2200–3700 m (Alström et
al., 2008; del Hoyo et al., 2006). The taxon L.
[t.] kashmirensis of the western Himalayas is now considered
to constitute a distinct species (Alström et al.,
2008).
Circumstances
of the find
Ringing has been implemented regularly at the privately administered
Nam Kham Nature Reserve since March 2008, mainly during the
months September to May, so as to primarily sample migrant and
wintering birds, in collaboration with Chiang Dao Wildlife Research
Station, Wildlife Research Division, Department of National
Parks, Wildlife and Plants Conservation. The 14.4 ha site lies
only a few km from the Mekong River and is managed primarily
for reedbed and wetland birds. In the present instance, a Greater
Coucal Centropus sinensis was seen flying away from
the immediate vicinity of the Spotted Bush Warbler when it was
found, having seemingly predated it. Some feathers were missing
from the right wing but no other external injuries were evident.
While an occasional predation incident may be inevitable, ringing
operations are carried out by well-trained ringers who do their
utmost to reduce netting accidents (there have been very few
in over 2,600 handlings of birds at the site.) The value of
results obtained through mist-netting, ringing and processing
birds is considerable, as both the present observation and earlier
observations (summarized in Pierce et al., 2013) indicate.
Figure 1. Spotted Bush Warbler Locustella
thoracica, found dead, Nam Kham Nature Reserve, Chiang
Saen, Chiang Rai Province, Thailand, 27 December 2013: A, ventral
view. B, view to show the underside of the tail in close-up.
Note the relatively long projection of tail beyond the under
tail-coverts, and also the very narrow whitish edges to the
latter. C, details of the wing formula. Note the relatively
long outermost primary (p 1); the wing point (p 4) and the relative
positions of p 3 and p 5. Photos by Woraphot Bunkhwamdi.
REFERENCES
Alstrom P., P. C. Rasmussen, U. Olsson and P. Sundberg. 2008.
Species delimitation based on multiple criteria: the Spotted
Bush Warbler Bradypterus thoracicus complex (Aves:
Megaluridae).Zool. J. Linn. Soc.154: 291–307.
Deignan, H. G. 1945. The birds of northern Thailand. US
Nat. Mus. Bulletin186. Smithsonian Institution,
Washington, DC:
Dickinson, E.C., P. C. Rasmussen, P. D. Round, and F. G. Rozendaal.
2000. A review of the Russet Bush Warbler, Bradypterus seebohmi
(Ogilvie-Grant, 1895). Systematic notes on Asian birds 1.
Zool. Verh. Leiden331: 11–64.
del Hoyo, J., A. Elliott, and D. A. Christie. 2006. Handbook
of the Birds of the World. Vol 11. Old
World Flycatchers to Old World Warblers. Lynx Edicions, Barcelona.
Gill, F. and D. Donsker (eds). 2014. IOC World Bird List
(v 4.4). doi : 10.14344/IOC.ML.4.4.
Lekagul, B., and P. D. Round. 1991. A guide to the birds
of Thailand. Saha Karn Bhaet, Bangkok.
Limparungpatthanakij, W., P. D. Round & S. Sutibut. 2014.
Records Roundup, Jan-Mar 2014. BCST Bull. 31
(1): 29–36.
Pierce, A. J., W. Bunkhwamdi & R. Kanjanavanit. 2013. The
first record of Common Chiffchaff Phylloscopus collybita
for Thailand. Birding ASIA20: 106–107.
Round, P. D. and V. Loskot. 1995. A reappraisal of the taxonomy
of the Spotted Bush-Warbler Bradypterus thoracicus.
Forktail10: 159–172.
Kindly
submitted by:
Woraphot Bunkhwamdi, PO Box 151, Chiang Mai University Post
Office, Muang, Chiang Mai 50202, Thailand. Email: zo_ic@yahoo.com
Rungsrit Kanjanavanit, Lanna Bird and Nature Conservation
Club, 76/1 Mu 14, Soi 5 Suthep Road, A. Muang, Chiang Mai 50200,
Thailand. Email: rungsritk@gmail.com
Andrew J. Pierce, Conservation Ecology Program, School of
Bioresources and Technology, King Mongkut’s University
of Technology Thonburi, Bangkhunthien, Bangkok 10150, Thailand.
Email: Andyp67@gmail.com
Philip D. Round, Department of Biology, Faculty of Science,
Mahidol University, Rama 6 Road, Bangkok 10400, Thailand. Email:
philip.rou@mahidol.ac.th
Central
Mongolia , 20th May-3rd June 2021 - Black-billed
Capercaillie, Oriental Plover, Henderson's Ground Jay, Azure
Tit, Pallas's Sandgrouse: Contact
me for details
Thailand
Raptor Migration, 26th Oct-5th Nov 2021 -
Black Baza, Grey-faced Buzzard, Pied Harrier, Lesser Fish
Eagle, Spoon-billed Sandpiper: Contact
me for details
Central
Mongolia , 20th May-3rd June 2021 - Black-billed
Capercaillie, Oriental Plover, Henderson's Ground Jay, Azure
Tit, Pallas's Sandgrouse: 
Thailand
Raptor Migration, 26th Oct-5th Nov 2021 -
Black Baza, Grey-faced Buzzard, Pied Harrier, Lesser Fish
Eagle, Spoon-billed Sandpiper: 
South
Korea, 5-17th January 2022 - Steller's Sea
Eagle, Relict Gull, Red-crowned Crane, White-naped Crane,
Baikal Teal, Solitary Snipe, Asian Rosy Finch: 
