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The discovery of Nonggang Babbler Stachyris nonggangensis in Vietnam

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Jonathan Eames
Jonathan Eames
Jonathan Eames
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Truong Nguyen at Universität Potsdam
Truong Nguyen
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Abstract

Nonggang Babbler Stachyris nonggangensis was newly described from Nonggang Natural Reserve, Guangxi Province, China in 2008. Following a later survey to gain a better understanding of the species range, the species was recorded at four new sites including Bangliang Gibbon Nature Reserve, which is located on the Sino-Vietnamese border. We visited Cao Vit Gibbon Species and Habitat Conservation Area between 4-12 October 2016 and found Nonggang Babbler thereby confirming its presence in Vietnam (and South-East Asia). This discovery extends its global range into a second range state and a third protected area.
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BirdingASIA 26 (2016): 29–31 29
Introduction
The Nonggang Babbler Stachyris nonggangensis
was described in 2008 from Nonggang National
Nature Reser ve, Guang xi province, Chi na, by
Zhou & Jiang (2008). The type locality is only 18
km from the Vietnamese border and since then
it has been speculated that the species’s range
extends into northern Vietnam (Zhou & Jiang 2008,
BirdLife International 2016). During a later survey
to gain a better understanding of the species’s
range, it was recorded at four new sites including
Bangliang Gibbon Nature Reserve, which is located
on the Sino-Vietnamese border (Li et al. 2013).
We assumed that the range of Nonggang Babbler
probably extended across the international border
into the Cao Vit Gibbon Conservation Area in Cao
Bang province, Vietnam, which we visited between
4 and 12 October 2016 and found Nonggang
Babblers there. This discovery extends its global
range into a third protected area.
Observations
At about 07h00 on 10 October 2016, JCE heard a
single distinctive downward-inflected whir ring
call of a Nonggang Babbler from forest on karst
limestone (Plates 1 & 2). Moments later he played
a recording of the same call (http://www.xeno-
ca nto.or g/2 2530) and a lm ost immediately a
RANGE EXTENSION
The discovery of Nonggang Babbler
Stachyris nonggangensis in Vietnam
JONATHAN C. EAMES & NGUYEN VAN TRUONG
Nonggang Babbler flew onto an exposed branch
about 4 m away and about 4 m high. The bird
was immediately identifiable by its pale blue iris,
white crescent on its ear coverts on an otherwise
dark head, and black and white throat mark ings.
After about 10 seconds it disappeared and did not
respond to further playback. A ride was quickly
cleared and a 12 m four-shelf mist-net erected
along a trail just off the main karst block (22.9°N
106.53°E) at 682 m. An iPhone set to play the same
downward-inflected call continuously was placed
Plate 1. View west wards across Cao Vit Gibb on Conservation Area, Cao Bang province, Vietnam, October 2016.
Plate 2. Forest habitat of Nonggang Babbler, Cao Vit Gibbon
Conservation Area, Cao Bang province, Vietnam, October 2016.
ALL IMAGES BY JO NATHAN C. EAMES
30 The discovery of Nonggang Babbler Stachyris nonggan gensis in Vietnam
about 3 m from the net at 08h15. At 14h00, contact
notes of an approaching Nonggang Babbler flock
were heard coming from the karst slope. The flock
of 10 birds flew straight towards the call; three
birds were caught, two of which were examined in
the hand, images obtained and the birds released
(Plate 4). Observations were also made of the flock
in the field (Plate 3).
In response to the alarm calls given by the
three birds in the net, the rest of the Nonggang
Babbler flock remained in the immediate vicinity
for 2–3 minutes, during which time they opened
their wings and held them in a downward position
in the manner of a broody domestic hen Gallus
gallus domesticus. They spread their tails and
raised the contour feathers on their backs, crowns,
napes and breast s. The overa ll effect was to
make the birds appear larger, and the side-to-side
movement accompanying this display was almost
mesmerising.
In the hand, both individuals examined were
in active moult. The first was in body moult; this
bird had lost and not yet replaced most of its
rectrices and only the four outermost remained.
All primary feathers had been renewed, except
for the un-moulted ninth primary on each wing,
whilst the first primar y of the right wing was in
pin. The second bird had moulted and replaced
all its rectrices and remiges and its body moult
was largely complete. Both individuals were noisy
and aggressive and tried to free themselves by
repeatedly using their robust chisel-like bills to pry
our fingers apart. The iris of both birds, and the
other members of the flock observed, was pale blue.
The legs and feet were robust and black with heavy
black claws. The soles of the feet were yellowish.
The bill was stout, long and slightly decurved. In
both birds the upper mandible was dark-blackish
horn, as was the lower, except for the distal portion
along the cutting edge, which was light horn.
Plate 3. Nonggang Babbler Stachyris nonggan gensis, showing the pale blue iris, Cao Vit Gibbon Conservation Area, Cao Bang
province, Vie tnam, 10 October 2016.
Plate 4. Nonggang Babbler Cao Vit Gibbon Conservation
Area, Cao Bang province, Vietnam, 10 October 2016.
BirdingASIA 26 (2016) 31
Discussion
This record confirms the anticipated occurrence
of the species in Vietnam, and furthermore is the
first record of moult in Nonggang Babbler.
During the field survey, Nonggang Babbler was
observed only on 10 October, although we were
working in closed canopy semi-evergreen forest
on karst limestone for most of the nine days. This
included the ascent of two karst hills, where the
only means of ascent was across the karst, and it
is surprising that we did not encounter the species
more frequently. However, it was not detec ted
during surveys in the type locality between 1997
and 2004, or at other sites where the species was
later found (Lee 2006). This suggests that it may
occur at low density or is very locally distributed
in forest on karst outcrops.
At Cao Vit Gibbon Conservation Area, the
main trail through a valley bottom was largely
on karst, but the visible outcrops were sma ller
and less extensive than where Nonggang Babbler
was recorded. This trail also had much dense
undergrowth inside secondary forest. Two other
Stachyris species were common in this habitat,
Grey-throated Babbler S. nigriceps and Spot-necked
Babbler S. striolata; consequently we assume that
such habitat is sub-optimal for Nonggang Babbler.
In the area where we recorded the species, we
also found Streaked Wren Babbler Napothera
brevicaudata, another bird that frequents karst
outcrops. The occurrence of Nonggang Babbler
in forest on karst and our observations of related
species are consistent with the earlier repor ts
(Zhou & Jiang 2008).
Non gg an g Babbler is consi der ed globa lly
Vulnerable and declining (BirdLife International
2016). The population has been estimated at 1,500
birds, with about 200 predicted to occur at the Cao
Vit Gibbon Conservation Area (Li et al. 2013). On
the basis of a single locality record for the species
in this protected area, it would be inappropriate
to predict a total population size or comment on
the validity of the current estimate for this site.
During our visit to this protecte d area we
encountered no illegal activity such as logging
or huntin g; indeed, we did not encounter any
unauthorised persons in the forest during our stay,
and those familiar with forests in Vietnam will
appreciate how unusual this is. This site supports
the largest remaining population of the Eastern
Black Crested Gibbon Nomascus nasutus and is
actively patrolled and managed by the Cao Bang
Forest Protection Department in collaboration
with Fauna and Flora International. Hunting is
reportedly rare, although collection of fuel wood
and logging are reported. The stable situation in
most of the reserve indicates that the population
of Nonggang Babbler at this site should be secure.
It is possible that Nonggang Babbler occurs at
other sites in Vietnam. The species has now been
recorded at Chunxiu Nature Reserve (22.237–
22.533°N 106.533–106.600°E), Guangxi province,
China (Li et al. 2013). This site is also located on
the Sino-Vietnamese border, and searching any
areas of forest on karst in the immediately adjacent
Trang Dinh district, Lang Son province, Vietnam,
would be wor thwhile. The Ch un xiu Nat ur e
Reserve is located only 55 km from Kim Ky Nature
Reserve (22.183–22.300°N 105.900–106.133°E) in
Bac An province which extends over 18,555 ha
and supports forest on karst. Additional sites in
Vietnam with suitable habitat where Nonggang
Babbler may occur include Nui Pia Oac Nature
Reserve (22.533–22.667°N 105.817–105.950°E),
Cao Bang province, and Huu Lien Nature Reserve
(21.617–21.750°N 106.317–106.433°E), Lan g Son
province (Tordoff et al. 2004).
Acknowledgements
We thank Cao Bang Forest Protection Department
and Faun a and Flora Internat ion al Viet na m
programme for facilitating our field survey.
References
BirdLife International (2016) Species factsheet: Stachyris nonggangensis.
Downloaded from http://www.birdlife.org on 23/10/2016.
Lee K. S., Lau M. W.-N., Fellowes, J. R., & Chan B. P. L., (2006) Forest bird
fauna of South China: notes on current distribution and status.
Forktail 22: 23–38.
Li Z., Zhou F., Lu Z., Jiang A., Yang G. & Yu C. (2013) Distribution, habitat
and status of the new species Nonggang Babbler Stach yris
nonggangensis. Bird Conserv. Internatn. 23 (4): 437– 444.
Tor doff, A. W., Tran Q. B ., N gu yen D. T. & Le M . H . (e ds. ) (2 00 4) Sourcebook
of existing and proposed protected areas in Vietnam. Second Edition.
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Jonathan C. EAMES
BirdLife International Cambodia Programme
No. 2, Street 476, Sangkat Toul Tum Poung 1
Khan Cham Kamorn, Phnom Penh, Cambodia
Email: Jonathan.Eames@birdlife.org
NGUYEN Van Truong
Fauna and Flora Vietnam Programme
340 Nghi Tam, Hanoi, Vietnam
... Li et al. (2013) found that NB was restricted to three out of 19 nature reserves and forest areas they surveyed in south-west Guangxi and south-east Yunnan Province, China. Eames and Truong (2016) also recently discovered NB in north-east Vietnam. Even with this foundation of research, the status of the species in the Sino-Vietnamese border area, and between the known sites of distribution in China, is poorly known. ...
... In total, including sites discovered by Li et al. (2013) and Eames and Truong (2016), there are four isolated sites in which NB is known to occur: 1) NGNNR, the reserve where NB was discovered, which is near the center of the species' distribution and contains well-preserved forest, 2) CXNR, a small reserve protected for water resources (78 km 2 ), which is separated by 25 km from NGNNR by agricultural lowlands surrounding the city of Longzhou, has some parts that are heavily impacted by human disturbance, and is adjacent to some unprotected forest tracts in Vietnam, 3) XLNR, the newly discovered site, with well-protected karst forest, separated by 20 km from NGNNR, and 4) BLGNNR and Cao Vit Gibbon Conservation Area (CVGCA), which are geographically connected, although separated by the border, are 27 km away from XLNR, and have some parts that are highly fragmented. The combined area of these four sites, including the total extent of each reserve, is 555 km 2 , which comprises 12.4% of the entire suitable habitat for NB (this figure does not include the Longshan sector of NGNNR, where NB has never been recorded; see Discussion). ...
... To conserve this threatened species, we suggest that further field surveys be (a) undertaken in Vietnam, which includes 25.8% of the suitable habitat, but where there is just one sighting to date (Eames and Truong 2016), and (b) focus on areas outside reserves in China that are of high or intermediate levels of habitat suitability in these models, to determine the degree of disturbance that NB can tolerate, and the minimum size of forest patch that can retain the species. Yet we have enough information for managers and policy makers to act now. ...
Modeling the distribution of Nonggang Babbler Stachyris nonggangensis , a threatened bird of limestone karst forests of the Sino-Vietnam border, and implications for its conservation
Article
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  • Jul 2019
Information on the geographic distribution of a species is fundamental for its conservation. Nonggang Babbler Stachyris nonggangensis (NB) is a rare and newly discovered species that is restricted to limestone karst forest on the Sino-Vietnamese border and has been classified as ‘Vulnerable’ due to its narrow distribution. However, the extent of the habitat suitable for NB is poorly known. We conducted a species distribution model (SDM) using 33 occurrence data and nine environmental variables. The SDM suggested highly suitable habitat covers 541 km ² , and habitat with a medium and low level of suitability covers 3,218 km ² and 722 km ² , respectively. Of the entire suitable habitat (low through high), 25.8% is in northern Vietnam and the rest is in Guangxi Zhuang Autonomous Region, southern China (especially concentrated in northern Longzhou and southern Daxing Counties). Unfortunately, only 12.4% of the entire suitable habitat is known to be occupied, and the habitat outside the reserves is highly threatened by fragmentation and degradation. Globally, NB is apparently isolated in only four sites, including one site in which we discovered its presence during field validation of the model. Based on this work, we suggest upgrading NB to the ‘Endangered’ category on the IUCN Red List and adding it to the list of endangered species of both China and Vietnam.
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Distribution, habitat and status of the new species Nonggang Babbler Stachyris nonggangensis
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  • Dec 2013
The Nonggang Babbler Stachyris nonggangensisis a new species of Timaliidae which was discovered in the Sino-Vietnamese border region in 2008. The species was initially classified as “Near Threatened” on the IUCN Red List and was believed to occur only in Nonggang Nature Reserve, where the type specimen was collected and where c.200 individuals were recorded. These few observations, and suggestions of a declining population, prompted us to initiate an extensive survey over the whole potential distribution range of this species in China from June 2009 to May 2011, during both dry and wet seasons. We conducted the survey in Guangxi Zhuang Autonomous Region and Yunnan Province and selected 19 reserves and forest areas where similar habitat to that in the Nonggang Reserve is known to occur. We used transects combined with playback to survey for this species. Nonggang Babbler was recorded at four new sites in the Sino-Vietnamese border region: two areas of the Nonggang Reserve (Nonggang and Longhu), Bangliang Gibbon Nature Reserve and Chunxiu Nature Reserve. The estimated population size of Nonggang Babbler was about 1,300 individuals in the four sites. Nonggang Babbler is also assumed to occur in the Trung Khanh Gibbon Reserve of Vietnam which adjoins Bangliang Gibbon Reserve. The estimated population in Trung Khanh is c.200 individuals. In total we estimate that the global population size of Nonggang Babbler is c.1,500 individuals. The Nonggang Babbler is restricted to karst forests, and its activities, foraging and nesting strictly rely on this habitat. Habitat loss and fragmentation are the main threats.
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A New Species of Babbler (Timaliidae: Stachyris) from the Sino-Vietnamese Border Region of China
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  • Apr 2008
Since 2004, we have surveyed birds in the southwest Guangxi Zhuang Autonomous Region of China. Many times during February, July, and October 2005 and January 2006, we observed, in Nonggang Natural Reserve of Guangxi, a species in the family Timaliidae that has never been recorded before in China or Southeast Asia. Nonggang Natural Reserve is located in the Sino-Vietnamese border region at 22 degrees 13'-22 degrees 34'N, 106 degrees 42'-107 degrees 05'E, 18 km southeast of the Vietnamese border. On 21 January 2006, we captured two individuals. Subsequent investigation showed that the specimens belonged to a previously undescribed species, which we designate Stachyris nonggangensis, the Nonggang Babbler.
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Sourcebook of existing and proposed protected areas in Vietnam
  • Jan 2004
  • A W Tordoff
  • Q B Tran
Tordoff, A. W., Tran Q. B., Nguyen D. T. & Le M. H. (eds.) (2004) Sourcebook of existing and proposed protected areas in Vietnam. Second Edition. Hanoi: BirdLife International in Indochina and the Ministry of Agriculture and Rural Development.