I have studied the Golden Spectacled warbler by gathering info from
books and the net, and I have also tried to compare the images of both
the species from Oriental Bird images repeatedly. Some differences are
quite distinct.
First I would like to mention that the Golden-spectacled Warbler,
usually treated as a single species, Seicercus burkii, is widely
distributed in mountains of southern Asia. But the Golden spectacled
is now treated as a 'Complex' of sibling species. It has been split
into five different species, one of which is described here for the
first time. Two species occur in sympatry in the Himalayas. The other
three species are found in eastern Asia, where all three are sympatric
in China, and two of these breed sympatrically also in Vietnam. In
Burma and adjacent parts of India, one of the Himalayan species is
sympatric with one of the east Asian species. There are differences in
morphology, vocalizations, altitudinal distribution and habitat
between these five species, as well as results from playback tests,
which show that all sympatric taxa differ and appear to be
reproductively isolated from each other. The Whistler's warbler is
actually a split from Golden Spectacled.
"Common" Golden-spectacled Warbler (Seicercus burkii)
(Burton) 1836
found in north India; Nepal; Bhutan; east Burma.
This has been split into many separate species. The eye ring of this
species is broken at the back, which is very prominent in the images
posted by Debarshi and Avishek. Moreover the colour of this species is
golden-yellow (which is also distinct in the images) as compared to
the more olive coloration of the Whistler's warbler (image attcahed).
The black bars on the crown of the S.burkii extend upto the bill
infront of the eye, which is quite distinct in many images. There is
no such difference in wing bars and edges of the two species.
Here are the splits and inserts:
Grey-crowned Warbler (Seicercus tephrocephalus)
(Anderson) 1871
c,sw China; north Vietnam; Burma
split from: Seicercus burkii
insert after: Seicercus burkii
Per Alström & Urban Olsson.
Whistler's Warbler (Seicercus whistleri) (Photo taken at Bulbuley
.Sikkim attcahed)...
Ticehurst 1925
Nepal, Bhutan, east India
split from: Seicercus burkii
insert after: Seicercus soror
Per Alström & Urban Olsson.
In this species, the ring is not broken anywhere, and it is more
greenish in colour. The blackish markings on crown do not reach the
bill. It is considered to be a high altitude species and have not been
been found to come down to the plains of lower Bengal ever. Its a
resident bird of the upper reaches of the Himalayas and never migrates
to the south. So the sudden sighting of a Whistler's warbler in a bird
sanctuary of south 24 Parganas is absurd.
Bianchi's Warbler (Seicercus valentini)
(Hartert) 1907
China; n Vietnam
split from: Seicercus burkii
insert after: Seicercus omeiensis
Per Alström & Urban Olsson.
Plain-tailed Warbler (Seicercus soror)
c,e China
insert after: Seicercus burkii
Per Alström & Urban Olsson
"Emei" Golden-spectacled Warbler (Seicercus omeiensis)
sw China: Sichuan province, Emei Mountains
insert after: Seicercus soror
J. Martens, S. Eck, M. Päckert & Y.-H. Sun.
In view of the above facts and features, I would like to conclude that
the birds seen by both Debarshi and Avishek are Golden Spectacled
Warblers (S. burkii). But more distinct images of the bird from CKBS
will be rather helpful to confirm this.
regards
Shantanu.
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