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Long-term count data demonstrate the regional signicance of Bako-Buntal
Bay, Malaysian Borneo, for wintering shorebird conservation
Batrisyia Teepol1*, Jia Jie Ng1, Daniel Kong1, Ding Li Yong2, Jason Jia Hong Teo1 & Nyat Jun Au1
1Malaysian Nature Society Kuching Branch, P.O. Box A144, Kenyalang Park, 93824, Kuching, Sarawak, Malaysia
2BirdLife International (Asia), Tanglin International Centre, 354 Tanglin Road, #01-16/17, Singapore, 247672
*Corresponding author: batrisyiatpl@gmail.com
Teepol, B., J.J. Ng, D. Kong, D.L. Yong, J.J.H. Teo & N.J. Au. 2021. Long-term count data demonstrate the regional
signicance of Bako-Buntal Bay, Malaysian Borneo, for wintering shorebird conservation. Wader Study 128(2):
xxx–xxx.
INTRODUCTION
Of the world’s nine major migratory yways, the East
Asian-Australasian Flyway (EAAF), which spans 22 coun-
tries, supports more migratory species than any other
yway, and is considered to be the most threatened of the
world’s yways (Conklin et al. 2014, Yong et al. 2018).
e Southeast Asian island of Borneo is a stopover and
staging area for migrating birds between northern Asia,
Southeast Asia and Australasia (McClure 1974, Bamford
et al. 2008, Mann 2008, Lim et al. 2020). ere is a
relatively well-established body of citizen science data on
bird migration in Borneo, and several coastal sites, such
as Kuala Baram and Pulau (= island) Bruit, are well
known for wintering shorebirds (e.g. Simpson 1983, Mann
2008). Moreover, recent satellite tracking of shorebirds
has provided novel evidence for how wetland sites along
the coastline of Borneo (e.g. in the Malaysian states of
Sabah and Sarawak, and Indonesia’s Kalimantan) are used
by shorebird species such as Great Knot Calidris tenuirostris,
Red Knot C. canutus and Sanderling C. alba as stopover
or staging sites (van Eerbeek 2013, Lisovski et al. 2016,
Chan et al. 2019a).
e 1,035 km coastline of Sarawak (Malaysian Borneo)
provides important wintering and staging grounds for
research paper Wader Study 128(2): xxx–xxx. doi:10.18194/ws.00239
Keywords
articial wetlands
East Asian-Australasian
Flyway
Far Eastern Curlew
Great Knot
migratory birds
mud and sand ats
Sarawak
Southeast Asia
Bako-Buntal Bay in Sarawak, Malaysia is among the most important coastal
wetlands for migratory shorebirds in Borneo, and in insular Southeast Asia.
However, since the multi-year waterbird surveys of the Sarawak coast during
2010–2012, there has been little published work on migratory shorebirds here.
Our study assessed the status and populations of migratory waterbirds utilizing
two sites within Bako-Buntal Bay: (1) the extensive mud and sand ats of Buntal
Bay used as a neap tide roost site, and (2) the man-made (ash) ponds at Sejingkat
regularly used as spring tide roost sites. We counted waterbirds twice a month
from October 2018 to March 2019, and compiled monitoring data from the
Asian Waterbird Census and other surveys starting in either 2006 or 2007. We
found a total of 32 waterbird species in Buntal and 31 species in Sejingkat,
including globally signicant numbers of four threatened species: Far Eastern
Curlew Numenius madagascariensis (EN), Great Knot Calidris tenuirostris (EN),
Nordmann’s Greenshank Tringa guttifer (EN), and Chinese Egret Egretta eulophotes
(VU). Our study showed that the total counts of waterbirds at Buntal, and
especially Sejingkat, have increased consistently from 2006–2007 to 2019,
particularly with an increasing trend for Far Eastern Curlew and a sudden increase
in Great Knot numbers in 2019. Using ag resightings, we established connections
between our study sites and sites along the East Asian-Australasian Flyway, e.g.
Chongming Island in Shanghai, China and Kamchatka in Russia. We are unsure
of the factors driving the increase of shorebird numbers, but hypothesize a
possible decline in habitat extent and quality elsewhere on Borneo or in the
wider Southeast Asian region. Our work demonstrates the continued importance
of Bako-Buntal Bay for shorebirds, especially the Far Eastern Curlew, in Southeast
Asia, and the need for sustained conservation measures.
more than 30 migratory waterbird species (Parish 1987,
Orenstein et al. 2010, Bakewell et al. 2017). It has a
diversity of coastal environments, ranging from rocky
shores, intertidal ats and sandy beaches, to large areas
of mangrove forests (Shabdin 2014), including some of
the most important areas of coastal wetlands within both
Malaysia and Southeast Asia, such as the Baram Estuary
and Bako-Buntal Bay (Li et al. 2006, Yeap et al. 2007,
MacKinnon et al. 2012, Bakewell et al. 2017, BirdLife
International 2020, Mehlman et al. 2020). In particular,
the extensive intertidal ats spanning the coastline of
Bako-Buntal Bay in southwest Sarawak (Fig. 1) are among
the most important sites for staging and over-wintering
waterbirds on Borneo, supporting not only high shorebird
diversity, but also globally signicant congregations of
threatened species such as Great Knot, Nordmann’s Green-
shank Tringa guttifer, Far Eastern Curlew Numenius
madagascariensis and Chinese Egret Egretta eulophotes
(Yeap et al. 2007, Mann 2008, Bakewell et al. 2017). In
2016, Bako-Buntal Bay was nominated as Malaysia’s rst
yway site (EAAF112) under the East Asian-Australasian
Flyway Partnership (EAAFP), giving it international
recognition. It is also one of 55 Important Bird and Bio-
diversity Areas (IBAs) in Malaysia (Chan et al. 2004,
Ye a p et al. 2007). However, despite its widely recognised
conservation value, Bako-Buntal Bay remains essentially
legally unprotected.
Although Bako-Buntal Bay is one of the best surveyed
coastal wetlands for shorebirds in Borneo, to date there
has been surprisingly little eort to assess the trends of
wintering shorebirds, or within-season variations in shorebird
abundance. Our study aimed to (1) determine whether
waterbird populations are using the Bako-Buntal Bay as
staging or wintering grounds, by estimating the monthly
variation in abundance and diversity of migratory waterbirds,
based on counts from October 2018 to March 2019, and
(2) determine long-term trends in the overall numbers of
waterbirds and of several important species based on long-
term data compiled from citizen counts from 2006 to 2019.
METHODS
Site information
We studied waterbird trends at two sites within Bako-
Buntal Bay (Fig. 1), an IBA of 3,590 ha (Bakewell et al.
2017, BirdLife International 2020). e coastline of Buntal
Bay (Teluk Buntal) stretches from a mountainous promon-
tory in the west to a densely forested cape protected
within the Bako National Park in the east (Yeap et al.
2007, Sarawak Forestry Corporation 2017). Our two study
sites within the Bako-Buntal Bay IBA are Buntal Bay
(hereaer Buntal) and the Sejingkat ash ponds (hereaer
Sejingkat) (Fig. 1).
–Wader Study 128(2) 2021
2
Fig. 1. Survey sites within the Bako-Buntal Bay Important Bird and Biodiversity Area (IBA) in Sarawak, Malaysian Borneo.
Buntal (1°41'45.6"N, 110°23'4.1"E) forms an integral part
of the wider Bako-Buntal Bay IBA and has large areas of
intertidal ats and sandbars that on neaps stay exposed
during high tides. Sejingkat (1°38'31.6"N, 110°27'56.2"E)
is part of the Sejingkat Coal Power Plant where a number
of large, man-made ponds are routinely lled with ash
waste from the plant. Both sites are important for
migratory shorebirds as high-tide roosts (e.g. Jackson et
al. 2020) while the intertidal ats at Buntal are also sig-
nicant feeding areas at low tide. We compiled waterbird
count data from three sources: our twice-monthly surveys
from October 2018 to March 2019, yearly surveys of the
Asian Waterbird Census (AWC) (2006–2019) and surveys
by Waterbird Survey of the Sarawak Coast (WSSC) in
2010–2012.
Survey methodology
Twice-monthly surveys – Buntal and Sejingkat were both
surveyed twice each month, for six months from October
2018 to March 2019. Most surveys at both sites were
undertaken when shorebirds were at high-tide roosts
(tide data from the Pulau Lakei tide station). Counts at
Buntal were conducted during neap tides (<4.5 m) as
birds y to Sejingkat to roost if the tide is too high,
whereas the counts at Sejingkat were carried out on
spring tides (>5.0 m). All waterbird species were identied
and counted using telescopes (20–60 × 88 mm) and
binoculars (10 × 40 mm). At Buntal, we used a small,
powered boat to reach an important part of the sand bar
at least two hours before high tide. When we reached the
sand bar, we carefully scanned the area before moving
towards the rst group of birds, taking care not to alarm
shorebird ocks. Once we had counted a ock, we moved
to the next until we reached the far end of the sand bar.
At Sejingkat, we arrived at the ash ponds at least an hour
before the high tide on the highest spring tide and waited
along the bund either using a hide or in a concealed area
to minimize alarming the arriving ocks. e birds were
counted once they had settled in the pond.
Birds were counted individually if possible, but large
ocks and birds in ight were estimated in multiples of
50 or 100. Count results were tabulated as the total
number of species observed, per site, per survey day. As
previous work had not accounted for birds that may have
been present both at Buntal on a neap tide and Sejingkat
on a spring tide, we took our counts to be independent,
although it is highly likely that there will be some overlap.
erefore the counts for the two sites were not added
together. We identied the birds using the relevant eld
guides (Phillipps & Phillipps 2014, Lee et al. 2018) and
all counts were conducted by a team consisting of at least
two experienced observers. We recorded potential threats
to shorebirds during the surveys.
Asian Waterbird Census – In Sarawak, monitoring work
and surveys on waterbirds have been carried out since
the 1980s (Howes & NPWO 1986a,b) and interest in
waterbird conservation has increased since then, although
there are few peer-reviewed studies (Edwards & Polshek
1987, Parish 1987, Mizutani et al. 2006). e AWC, which
forms a part of the International Waterbird Census (IWC)
has been conducted annually in Asia since 1987 (Wetlands
International 2007). In Sarawak, the AWC counts have
been carried out nearly annually by citizen scientists
from the Malaysian Nature Society (from its chapters in
Kuching and Miri, a leading conservation non-government
organisation in Malaysia). e AWC counts provide an
important source of time-series data for shorebirds at
various wetland sites across Sarawak. We extracted and
compiled AWC data for Buntal and Sejingkat, compared
them to our survey data, and analysed the trends. Data
were available for 2006–2009 (from 2007 at Sejingkat)
and 2017–2019 for both sites. Waterbird counts under
the AWC surveys are typically land-based and on foot,
using telescopes and binoculars, and were very similar to
our methodology.
Waterbird Survey of the Sarawak Coast (WSSC) – Surveys
were conducted from 6 October 2010 to 9 April 2011,
and 28 October 2011 to 21 February 2012, during or
near high tide. e total number of individuals for each
sector was the sum of the maximum single-day counts
for each species. WSSC data were collected using three
dierent approaches, depending on the level of accessibility
of the sites: land-based surveys, boat-based surveys, and
aerial surveys (by helicopter) for the most inaccessible
sites. We extracted data for Buntal and Sejingkat from
two sectors dened under the WSSC surveys (i.e. 5, 7
respectively). At Buntal, boat-based surveys were conducted
on 19 January 2011, both land and boat-based surveys
were conducted on 20 January and 27 October 2011,
and an aerial survey on 26 January 2011. At Sejingkat,
there were ve land-based surveys (23 Jan, 18, 20 & 21
Feb, 27 Oct 2011), and one aerial survey on 26 October
2011.
Land-based surveys were carried out in either a four-
wheel-drive vehicle or on foot. Observations were conducted
using binoculars (10 × 40mm), telescopes (20–60 × 88
mm) and a digital camera (300 mm). Each survey involved
at least two surveyors, a counter and a scribe. Boat-based
surveys were conducted with binoculars or, wherever
possible, counters would access the shoreline to count.
Aerial surveys were conducted if shorebird roosts were
inaccessible from land and sea, using a Bell-206 four-seat
helicopter with three hours of endurance time. ree
surveyors would typically take part: a navigator, a recorder
and a photographer. Photographs of ocks were consistently
taken to estimate species abundances and identify species
in ocks whenever necessary. Specic details of all surveys
under the WSSC are available in Bakewell et al. (2017).
Analysis of count trends
We assessed trends in populations for all threatened
species (Far Eastern Curlew, Great Knot, Nordmann’s
Greenshank and Chinese Egret) using the maximum
count from our surveys and those from the AWC and
WCCS datasets. e datasets for these four species were
analysed according to the years of available data ranging
Teepol et al. l Wintering shorebirds in Bako-Buntal Bay, Malaysian Borneo–3
from 2005–2019. e data were compiled using Microso
Excel, analysed using simple linear regression models in
R (R Core Team 2020) and the trend lines and 95% con-
dence intervals were plotted using ggplot2 (Wickham
2016). A map of our study site was created using the Free
and Open source QGIS (QGIS 2020).
RESULTS
Counts and seasonal trends in 2018–2019
In our 2018 and 2019 surveys, we recorded a total of 32
waterbird species in Buntal, and 31 in Sejingkat (Table
S1) and observed large variation in high counts between
the two sites and between species (Table S2). Our highest
single-day counts for waterbirds was 8,374 at Buntal (16
Jan 2019) and 8,785 at Sejingkat (24 Nov 2018) (Fig. 2,
Tables S3 & S4). At both sites, the lowest total count of
roosting birds throughout this survey was in December
2018 (2,647 at Buntal and 545 at Seijingkat).
Great Knot was the most numerous shorebird at both
sites, with maximum counts of 2,000 individuals in Buntal
and 2,500 in Sejingkat (Table 1, Fig. 3). e next most
abundant species in Buntal were Greater Sand Plover
Charadrius leschenaultii (maximum: 2,000) and Lesser
Sand Plover Ch. mongolus (maximum: 1,800) (Table S2).
e next most abundant species in Sejingkat were Bar-
tailed Godwit Limosa lapponica (maximum: 1,700) and
Black-tailed Godwit L. limosa (maximum: 1,500).
We found large month-to-month variation in numbers at
both Buntal and Sejingkat in Bar-tailed Godwits and
Great Knots, but less so in the two curlew species (Fig.
3). Daily maximum counts of Great Knot at Buntal peaked
in October 2018, and progressively declined to December,
before reaching a second peak of over 1,800 individuals
on 16 January (Fig. 3). Bar-tailed Godwits at Buntal were
relatively stable. ere was a similar pattern at Sejingkat
for both Bar-tailed Godwits and Great Knots, with peak
counts in November and January. Counts of Far Eastern
Curlew at Buntal peaked at 600 individuals in November
before gradually declining. By contrast, counts of Far
Eastern Curlew remained consistent at Sejingkat (250–
450 individuals). Eurasian Curlew show similar levels
but slightly lower peak numbers of 400 individuals.
Of the globally threatened species, at Buntal we had a
maximum count on a single day of 600 Far Eastern
Curlew (EN), 2,000 Great Knot (EN), seven Nordmann’s
Greenshank (EN), and 40 Chinese Egret (VU). While at
Sejingkat the gures were 450 Far Eastern Curlews (EN),
2,500 Great Knot (EN) and four Nordmann’s Greenshank
(EN).
Yearly trends in non-breeding waders
In the January 2011 survey of the Sarawak coast conducted
by WSSC, a total of 8,616 individuals of 27 species was
counted at Buntal, and 1,447 individuals of 17 species at
Sejingkat (Bakewell et al. 2017) (Fig. 4).
e total waterbird count by AWC at Buntal appeared
relatively stable from 2006 (4,212 individuals) to 2019
(5,969), with a peak of 9,335 birds in 2017 (Fig. 4). At
–Wader Study 128(2) 2021
4
Fig. 2. Total waterbird abundance per month Oct 2018–
Mar 2019 in the Buntal Bay (black) and Sejingkat (gray)
count sites within the Bako-Buntal Bay Important Bird and
Biodiversity Area in Sarawak, Malaysian Borneo. Total
abundance is based on single-day maximum counts.
Fig. 3. Maximum daily counts for four key shorebird
species, Great Knot, Eurasian Curlew, Far Eastern Curlew,
and Bar-tailed Godwit in Buntal Bay (upper panel) and
Sejingkat (lower panel), throughout the six months of our
study (Oct 2018–Mar 2019).
Maximum daily count
Sejingkat, the total AWC count increased from 2007 to
2019 from 484 to 7,358 individuals (Fig. 4); the sudden
large increase in 2019 was partly driven by an increase in
Great Knots, with 1,752 individuals using the site in 2019.
Using the same dataset, we compiled the total species
numbers from 2007–2009, 2011 and 2017–2019 (Fig. 4).
At both sites, the number of species observed uctuated
from year to year (Buntal: 14–33; Sejingkat: 8–24). However,
the total number of species throughout our study in
2018–2019 in Sejingkat was considerably higher (31)
although it was quite similar for Buntal (32).
Of the globally threatened species, counts of Far Eastern
Curlew over time have shown a large and highly signicant
increase in Sejingkat (R2 = 0.88, P = 0.001; Fig. 5b) but
not at Buntal (Fig. 5a). No signicant trends were detected
for Great Knot, Nordmann’s Greenshank (Fig. 5c–f) or
Chinese Egret (not shown) (all P > 0.05).
Leg flag resightings
Flagged individuals of ve species were found, with a
total of 17 sightings of an unknown number of individuals
(see Table S5 for more details). Most of the sightings
involved birds banded on Chongming Island, Shanghai,
China on the Yellow Sea coast (n = 10) and Kamchatka,
Russia (n = 4). Leg-agged Great Knots were from Chong-
ming Island (n = 3), Kamchatka (n = 3), and northern
Japan (n = 1). All Far Eastern Curlew and Nordmann’s
Greenshank were from Chongming Island (n = 3 and 2) .
Red-necked Stints Calidris rucollis were mostly from
Chongming Island (n = 3), and also from Java or Bali,
Teepol et al. l Wintering shorebirds in Bako-Buntal Bay, Malaysian Borneo–5
Table 1. The importance of Buntal and Sejingkat (Bako-Buntal Bay, Sarawak, Malaysian Borneo) for globally threatened
waterbird species, based on the 1% yway criteria, where the Threshold refers to the number representing 1% the total
yway population (based on Wetlands International 2021). Highest count refers to highest count on a single day
between 2006–2007 and 2019. Counts exceeding the 1% Threshold are in bold.
Common name Scientic
name
IUCN
Conservation
Status
Highest
count
in Buntal
Highest
count in
Sejingkat
1%
Threshold
Far Eastern Curlew Numenius madagascariensis EN 600 450 320
Great Knot Calidris tenuirostris EN 2,000 2,500 2,900
Nordmann’s Greenshank Tringa guttifer EN 74 5
Chinese Egret Egretta eulophotes VU 40 N/A 35
Fig. 4. Upper panels: total waterbird abundance during the non-breeding season in Buntal Bay (2006–2019; left panels)
and in Sejingkat (2007–2019; right panels). Lower panels: total number of waterbird species at both sites. Data from
2011 are extracted from WSSC and the other years from AWC. NB: No surveys were conducted in 2010 and 2012. Counts
conducted in Dec/Jan are indicated by their terminal year, e.g. 2019 includes counts in Dec 2018 covering the boreal
winter of 2018–2019.
Indonesia (n = 1) and Kamchatka, Russia (n = 1). e
single Red Knot was banded on the North Island of New
Zealand.
DISCUSSION
Important roosting sites and significance for EAAF
shorebirds
Our surveys show that both Buntal and the adjacent ash
ponds at the Sejingkat power station are globally important
staging and wintering sites for migratory waterbirds, and
continue to sustain signicant populations of four globally
threatened migratory waterbirds. Both are considered as
among the most important areas for shorebirds on the
Sarawak coast (Yeap et al. 2007, Bakewell et al. 2017, Lim
et al. 2020), and potentially in all of Malaysian Borneo.
Note that there are large gaps in knowledge of shorebird
distributions on the Indonesian Borneo coastline, which
potentially contains unknown important areas for shorebirds.
Based on past surveys and citizen science observations,
the intertidal ats of Buntal are an important wintering
site for several threatened species such as Chinese Egret
and Far Eastern Curlew (Mann 2008, Phillipps & Phillipps
2014). Our study shows that the wetlands of Buntal
harbour more than 1% of the EAAF population of the
Chinese Egret (ca. 1.14%) and Nordmann’s Greenshank
(ca. 1.40%) in mid-winter. Both sites also hold over 1% of
the EAAF populations for passage or wintering Far Eastern
Curlew (ca. 1.88% in Buntal, 1.41% in Sejingkat). From
November to December 2018, our monthly surveys at
both sites showed a decrease in overall shorebird numbers,
with a rapid increase in January 2019. is increase may
be due to localised dispersal of wintering bird species
along the wider Sarawak coastline, such as Greater Sand
Plovers Charadrius leschenaultii and Grey Plovers Pluvialis
squatarola. From our surveys, counts of Great Knot
peaked in October (Buntal) and November (Sejingkat)
(Fig. 3). e number then drastically decreased before
reaching another peak around January, and continue to
decline until the end of the migration period. is suggest
that the birds are roosting at dierent areas during the
winter. A dierent case can be seen for Far Eastern
Curlew where their numbers in both sites seem to appear
quite stable throughout the entire non-breeding period.
Species of conservation concern: comparison with
previous surveys
Four species of waterbirds of conservation concern
occurred in globally signicant numbers at our study
sites – Chinese Egret (VU), Far Eastern Curlew (EN),
Nordmann’s Greenshank (EN) and Great Knot (EN) –
and will need to be regularly monitored in the longer
term. Our data suggest that the maximum wintering Chi-
nese Egret population in Buntal is around 40 and may
have slightly declined over time (not shown) and this
may potentially reect wider patterns of population
change. Given the global signicance of Buntal for the
species (>1% of the EAAF population; see Table 1, also
Orenstein et al. 2010, Bakewell et al. 2017) as one of few
monitored wetlands important to the species within its
Southeast Asian wintering range, there is a need to better
study the species’ ecology not only on the Borneo coast,
but more widely across the yway to determine regional
trends.
We used unpublished and published AWC and WSSC
data (e.g. Bakewell et al. 2017) to determine overall trends
in waterbird abundance, and individual trends for Far
Eastern Curlew, Great Knot and Nordmann’s Greenshank.
Our comparisons show that the total number of waterbird
species uctuated at both sites, although there was a sub-
stantial increase in numbers at both sites in 2019, partic-
ularly among Far Eastern Curlew and Great Knot (Fig.
5). e total count of Far Eastern Curlew in Sejingkat
nearly doubled from 581 to 970 individuals from 2018 to
2019. e total count of Great Knot in Buntal was 800
individuals in 2011, but this has since more than doubled
to a maximum count of ca. 1,800 individuals in 2019.
Note that in January 2019 our survey and AWC found a
similar number of individuals, but both counts were
–Wader Study 128(2) 2021
6
Fig. 5. Population trends of Far Eastern Curlew, Great Knot
and Nordmann’s Greenshank during the non-breeding
season in Buntal Bay (2006–2019; left panels) and in
Sejingkat (2007–2019; right panels), based on AWC and
WCSS data from 2005–2006 or 2006–2007 to 2019.
lower than during our survey in October 2018 where we
counted a maximum of ca. 2,000 Great Knots. At Sejingkat,
the Great Knot count was only 80 individuals in 2011 but
the maximum count in 2019 was ca. 1,752 individuals.
e large increases in counts of these two threatened
shorebirds are unusual, given that global populations of
both Great Knot and Far Eastern Curlew are in decline
(Conklin et al. 2014, BirdLife International 2020) and are
unlikely to have arisen from dierences in observer skill
and eort alone. ere are three possible explanations:
(1) as yet undetected habitat loss along the Sarawak
coastline, or degradation of the quality of mud and sand
ats habitat may have forced staging or wintering birds
to relocate to Buntal and Sejingkat; (2) populations
wintering elsewhere in the region (e.g. Australia) may
have adjusted and shortened their migrations, and are
now wintering in Borneo, driving up localized abundances
of wintering birds as has been reported elsewhere in
Southeast Asia (e.g. Round & Bakewell 2015); (3) since
the sites were surveyed during dierent tidal phases, the
dierences in numbers may arise due to the congregation
of dierent groups of Great Knot foraging at sites along
the coastline north of the bay to the Sungai (= river)
Batang Lupar, and were thus unaccounted for by the
Buntal surveys. Further satellite tagging work (e.g. Chan
et al. 2019a) may help to resolve these knowledge gaps,
and the movement of dierent ocks potentially driving
these observed variations.
Other important sightings and records
During our surveys, we observed two Black-headed Gulls
Chroicocephalus ridibundus at Sejingkat in January 2019,
and a single Lesser Crested Tern alasseus bengalensis
at Buntal in March 2019. Both species are of Least Concern
(LC) but are considered as rare species with very few
records from the Sarawak or the wider Bornean coastline.
Further surveys at both sites can be expected to detect
stragglers and other rare shorebirds.
Threats to migratory shorebirds
We found no evidence of hunting at Buntal or Sejingkat
during our surveys, unlike many other coastal parts of
Southeast Asia where shorebirds hunting is widespread
(Gallo-Caijiao et al. 2020, Nguyen et al. 2020). However,
we saw extensive plastic waste pollution along the shoreline
with high concentrations at high tide roosts. is may
have detrimental eects on coastal wildlife and the mudat
benthos over time as plastic waste would break down
into microplastics. Although there is limited information
on the eect of microplastics on animals, it has been sug-
gested that plastic pollution could pose a longer-term
threat aecting shorebirds if ingested (Rossi et al. 2019).
e ash ponds in Sejingkat are man-made wetlands,
similar to those in Kapar, Peninsular Malaysia (see Li et
al. 2006, Jackson et al. 2020) and were created for dumping
ash residues from a coal red power station. Once the
ponds have been fully lled in, new ponds are usually
dug. Noise pollution from the power station and ash
dumping operations may disturb the roost, and there
may also be negative eects of chemical pollutants leached
from ash. However, the habitat may be lost in the future
if the power station stops operating, as local power gen-
erators are turning to renewable energy.
Flyway connections
Our surveys found several shorebirds, including three
threatened species (e.g. Great Knot, Far Eastern Curlew,
Nordmann’s Greenshank) that were leg-agged on Chong-
ming Island on the Yellow Sea coast of China, demonstrating
the migratory linkages between shorebird populations
staging in the Yellow Sea, and those overwintering in
Borneo. Furthermore, the staging site in Kamchatka,
Russia was represented by three of seven resightings of
Great Knots and one in four Red-necked Stints, conrming
the role of this staging site in the yway (Dorofeev &
Kazansky 2013). Recent studies such as Chan et al. (2019a)
further demonstrate the migratory routes of satellite-
tagged Great Knot linking Borneo and the Yellow Sea
coast of China, the Koreas and Kamchatka. e coastal
wetlands along the Yellow Sea form important refuelling
stops for shorebirds on the EAAF (Barter 2002), and thus
declines in the condition of coastal wetlands there will
have far reaching, knock-on eects on shorebird populations
throughout the yway, including populations staging or
wintering on Borneo’s coastline and elsewhere in Southeast
Asia. Large areas of wetlands on the Yellow Sea coastline
have already been lost due to coastal development (Murray
et al. 2014) and there is strong evidence now that the
higher the reliance of shorebirds on these wetlands, the
steeper they decline (Studds et al. 2017). Although there
have been new developments from governments to limit
coastal land reclamation (e.g. BirdLife International 2018),
coastal areas of the Yellow Sea face heavy development
pressure which has resulted in substantial habitat loss
(Murray et al. 2014, Chen et al. 2019, Duan et al. 2020);
this could aect the shorebird populations connecting
these areas and the Bornean coastline, including wetlands
in Bako-Buntal Bay.
Recommendations for future work
Borneo forms one of the least known parts of the EAAF
for migratory shorebirds, and is only beginning to become
better studied through satellite tracking and ground-
based surveys such as ours. Our study summarised new
(from our eld work) and unpublished data on shorebird
assemblages and their abundance trends over time at
Bako-Buntal Bay, arguably Borneo’s best known site for
shorebirds, and conrms that it remains a signicant
wetland for shorebird conservation, especially for Far
Eastern Curlew. Our leg-ag observations and recent
studies (e.g. Chan et al. 2019a) demonstrate the connections
between shorebird populations migrating between the
Borneo coastline and the Yellow Sea. Moving forward,
strengthened legal protection of this coastline should be a
priority of the Sarawak State government alongside mon-
itoring. Further surveys should aim to determine other
potentially important sites as roosts and foraging areas
for shorebirds in Bako-Buntal Bay, as well as the extensive
Teepol et al. l Wintering shorebirds in Bako-Buntal Bay, Malaysian Borneo–7
mud and sand ats-dominated coastline in southwest
Sarawak. Coordinated counts starting from the arrival of
the birds to their departure to their breeding grounds,
and tagging studies (e.g. Chan et al. 2019a,b), should be
conducted in the future to better understand the use of
dierent sites by shorebird populations within the region.
Lastly, there is a need for further engagement with local
stakeholders, including the management of Sejingkat
Power Station to establish long-term plans to manage
these man-made wetlands, while potentially forging col-
laborative relationships (e.g. sister-site twinning) with
international stakeholders to build capacity for migratory
species conservation (Mehlman et al. 2020).
ACKNOWLEDGEMENTS
We thank the Conservation Leadership Programme (CLP)
for funding and supporting this entire project, Oswald
Braken Tisen, Rambli Ahmad and Noraisah Majri (Sarawak
Forestry Corporation), Balu Perumal (Malaysian Nature
Society Headquarters), Malaysian Nature Society Kuching
Branch, Sarawak Energy Berhad (SEB), Dave Bakewell
and Anthony Wong, Prof. Andrew Alek Tuen and Dr.
Fizl Sidq of University Malaysia Sarawak for their endless
support. We are also grateful to Ng Wai Pak (Malaysian
Nature Society Headquarters) who provided useful data
on previous AWC counts. We thank Ginny Chan and an
anonymous reviewer for their helpful comments.
ONLINE SUPPLEMENTARY INFORMATION
Table S1. All species recorded during our eld surveys of
Buntal and Sejingkat, in Bako-Buntal Bay, Sarawak, Malay-
sian Borneo.
Table S2. Highest count for each species found in each
site (Buntal or Sejingkat) in Bako-Buntal Bay, Sarawak,
Malaysian Borneo.
Table S3. Total count for waterbirds in Buntal in Bako-
Buntal Bay (Sarawak, Malaysian Borneo) throughout the
entire survey.
Table S4. Total count for waterbirds in Sejingkat in Bako-
Buntal Bay (Sarawak, Malaysian Borneo) throughout the
entire survey.
Table S5. List of leg-agged birds recorded during our
surveys of Buntal and Sejingkat, in Bako-Buntal Bay,
Sarawak, Malaysian Borneo.
REFERENCES
Bakewell, D., A. Wong, D. Kong & R. Au. 2017. Wat er b ir d
Surveys of the Sarawak Coast (2010–2012). MNS Conser-
vation Publication No. 13, Malaysian Nature Society,
Kuala Lumpur, Malaysia.
Bamford, M., D. Watkins, W. Bancro, G. Tischler & J.
Wahl . 2008. Migratory Shorebirds of the East Asian-Aus-
tralasian Flyway: Population Estimates and Internationally
Important Sites. Wetlands International – Oceania, Canberra,
Australia.
Barter, M.A. 2002. Shorebirds of the Yellow Sea – importance,
threats and conservation status. Wetlands International
Global Series 9 and International Wader Studies 12. Wet-
lands International – Oceania, Canberra, Australia.
BirdLife International. 2018. Great news for shorebirds!
China to halt coastal land reclamation. Accessed 14 Nov
2020 at: www.birdlife.org
BirdLife International. 2020. Important Bird Areas factsheet:
Bako-Buntal Bay. Accessed 7 Jun 2020 at: www.birdlife.org
Chan, S., M.J. Crosby, M.Z. Islam & A.W. Tordo. 2004.
Important Bird Areas in Asia: Key Sites for Conservation.
BirdLife International, Cambridge, UK.
Chan, Y.-C.,T.L. Tibbitts, T. Lok, C.J. Hassell, H.-B. Peng,
Z. Ma, Z. Zhang & T. Piersma. 2019a.Filling knowledge
gaps in a threatened shorebird yway through satellite
tracking.Journal of Applied Ecology56:2305–2315.
Chan, Y.-C., H.-B. Peng, Y.-X. Han, S.S.-W. Chung, L. Li,
L. Zhang & T. Piersma. 2019b. Conserving unprotected
important coastal habitats in the Yellow Sea: Shorebird
occurrence, distribution and food resources at Lianyungang.
Global Ecology & Conservation 20: 1–10.
Chen, Y., J. Dong, X. Xiao, Z. Ma, K. Tan, D. Melville, B.
Li, H. Lu, J. Liu & F. Liu. 2019. Eects of reclamation
and natural changes on coastal wetlands bordering China’s
Yellow Sea from 1984 to 2015. Land Degradation & Devel-
opment 30: 1533–1544.
Conklin, J.R., Y.I. Verkuil & B.R. Smith. 2014. Prioritizing
migratory shorebirds for conservation action on the East
Asian-Australasian Flyway. WWF – Hong Kong. Accessed
7 Jun 2020 at: http://awsassets.wwk.panda.org
Dorofeev, D.S. & F.V. Kazansky. 2013. Post-breeding stopover
sites of waders in the estuaries of the Khairusovo, Belo-
golovaya and Moroshechnaya rivers, western Kamchatka
Peninsula, Russia, 2010–2012. Wader Study Group Bulletin
120: 119–123.
Duan, H., S. Xia, M.V. Jackson, N. Zhao, Y. Liu, J. Teng, Z.
Meng, X. Yu & J. Shi. 2020. Identifying new sites of sig-
nicance to waterbirds conservation and their habitat
modication in the Yellow and Bohai Seas in China.
Global Ecology & Conservation 22: e01031.
Edwards, P.J. & P.M. Polshek. 1987. A wader survey of the
western coastline of Sarawak. Sarawak Museum Journal
XXXVII: 181–192.
Gallo-Cajiao, E., T.H. Morrison, B.K. Woodworth, A.C.
Lees, L.C. Naves, D.L. Yong, C.-Y. Choi, T. Mundkur,
A. Jain, K. Klokov, E. Syroechkovskiy, S.U. Chowdhury,
V.W.K. Fu, J.E.M. Watson & R.A. Fuller. 2020. Extent
and potential impact of hunting on migratory shorebirds
in the Asia-Pacic. Biological Conservation 246: 108582.
Howes, J.R. & NPWO. 1986a. Evaluation of Sarawak wetlands
and their importance to waterbirds. Report 3. Pulau Bruit.
(INTERWADER Publ. No. 10). INTERWADER, Kuala
Lumpur, Malaysia.
Howes, J.R. & NPWO. 1986b. Evaluation of Sarawak wetlands
and their importance to waterbirds. Report 4. Limbang/Lawas
Districts of Brunei Bay. (INTERWADER Publ. No. 14).
INTERWADER, Kuala Lumpur, Malaysia.
Jackson, M.V., C.-Y. Choi, T. Amano, S.M. Estrella, W.
Lei, N. Moores, T. Mundkur, D.I. Rogers & R.A. Fuller.
–Wader Study 128(2) 2021
8
2020. Navigating coasts of concrete: Pervasive use of
articial habitats by shorebirds in the Asia-Pacic. Biological
Conservation 247: 108591.
Lee, W.-S., C.-Y. Choi & H. Kim. 2018. Field guide to the
waterbirds of ASEAN. ASEAN-Korea Environmental
Cooperation Unit (AKECU), Seoul, South Korea.
Li, D.Z.W., C.A. Yeap, K.C. Lim, K. Kumar, A.T. Lim, C.
Yan & W.M. Choy. 2006. Shorebird surveys of the
Malaysian coast Nov 2004–Apr 2005. Stilt 49: 7–18.
Lim, K.S., D.L. Yong, K.C. Lim & D. Gardner. 2020. Field
guide to the birds of Malaysia and Singapore. John Beaufoy
Publishing Ltd, Oxford, UK.
Lisovski, S., K. Gosbell, M. Christie, B.J. Hoye, M. Klaassen,
I.D. Stewart & C. Minton. 2016. Movement patterns of
sanderling (Calidris alba) in the East Asian-Australasian
Flyway and a comparison of methods for identication
of crucial areas for conservation. Emu 116: 168–177.
MacKinnon, J., Y.I. Verkuil & N. Murray. 2012. IUCN situ-
ation analysis on East and Southeast Asian intertidal
habitats, with particular reference to the Yellow Sea (including
the Bohai Sea). Occasional Paper of the IUCN Species
Survival Commission No. 47. IUCN, Gland, Switzerland
& Cambridge, UK.
Mann, C.F. 2008. e Birds of Borneo. BOU Checklist No
23. British Ornithologists’ Union, Tring, UK.
McClure, H.E. 1974. Migration and survival of the birds of
Asia. U.S. Army Medical Component, SEATO Medical
Project. White Lotus Press, Bangkok, ailand.
Mehlman, D.W., J.A. Fitzsimons, A. Irving, J. Irving & B.
Hancock. 2020. Selecting a suite of potential partner
sites for the Adelaide International Bird Sanctuary to aid
shorebird conservation in the East Asian–Australasian
Flyway. Pacic Conservation Biology 26: 67–77.
Mizutani, A., K. Kato, K. Tanaka, T. Ichikawa, M. Zaidi &
I. Auby. 2006. A Report of the Wintering Waterbirds Status
along the West Coast of Sarawak – Results of AWC 2006.
Sarawak Forestry, Kuching, Malaysia.
Murray, N.J., R.S. Clemens, S.R. Phinn, H.P. Possingham
& R.A. Fuller. 2014. Tracking the rapid loss of tidal
wetlands in the Yellow Sea. Frontiers in Ecology & the
Environment 12: 267–272.
Nguyen, H.B., Q.T. Cao, T.T. Bui & D.L. Yong. 2020. Salt
pans and coastal ats on the coast of Binh uan – a new
site for the Spoon-billed Sandpiper in Vietnam. Spoon-
billed Sandpiper Task Force News Bulletin 22: 12–16.
Orenstein, R., A. Wong, N. Abghani, D. Bakewell, J. Eaton,
S.T. Yeo & D.L. Yong. 2010. Sarawak – a neglected
birding destination in Malaysia. BirdingAsia 13: 30–41.
Parish, D. 1987. Conference on wetland and waterfowl con-
servation in Asia 23rd–28th Feb 1987, Malacca. Accessed
10 Jun 2020 at: http://repository.wwf.org.my/conference/
ConferenceOnWetlandAndWaterfowlConservationInAsia.pdf
Phillipps, Q. & K. Phillipps. 2014. Phillipps’ Field Guide to
the Birds of Borneo: Sabah, Sarawak, Brunei, and Kalimantan,
3rd edn. Princeton University Press, New Jersey, USA.
QGIS. 2020. QGIS Geographic Information System. Open
Source Geospatial Foundation Project.Accessed 24 Jul
2020 at: http://qgis.org
R Core Team. 2020. R: A language and environment for sta-
tistical computing. R Foundation for Statistical Computing,
Vienna, Austria. Accessed 20 Jul 2020 at: https://www.R-
project.org
Rossi, L.C., A.L. Scherer & M.V. Petry. 2019. First record
of debris ingestion by shorebird American Oystercatcher
(Haematopus palliatus) on the Southern coast of Brazil.
Marine Pollution Bulletin 138: 235–240.
Round, P. & D. Bakewell. 2015. Steep upward trajectory in
Great Knot numbers at sites in South-East Asia. Tattler
35: 2–4.
Sarawak Forestry Corporation. 2017. Dossier Bako Buntal
Bay East Asian-Australasian Flyway Network Site: Concept
for sustainable use. Accessed 20 Jun 2020 at: https://eaay-
way.net
Shabdin, M.L. 2014. Sarawak coastal biodiversity: A current
status. Kurishio Science 8: 71–84.
Simpson, D.M. 1983. Autumn migration of landbirds o
North Borneo in 1981. Sea Swallow 32: 48–53.
Studds, C.E., B.E. Kendall, N.J. Murray, H.B. Wilson, D.I.
Rogers, R.S. Clemens, K. Gosbell, C.J. Hassell, R. Jessop,
D.S. Melville, D.A. Milton, C.D.T. Minton, H.P. Poss-
ingham, A.C. Riegen, P. Straw, E.J. Woehler & R.A.
Fuller. 2017. Rapid population decline in migratory shore-
birds relying on Yellow Sea tidal mudats as stopover
sites.Nature communications 8: 14895.
van Eerbeek, J. 2013. Research report 1: e eects of satellite
tags on Red Knots (Calidris Canutus) in Roebuck Bay, Australia.
MSc thesis, University of Groningen, e Netherlands.
Wetlands International. 2007. e Asian Waterbird Census:
Development Strategy 2007–2015. Accessed 24 Jun 2020
at: https://wpe.wetlands.org
Wetlands International. 2021. Waterbird Population Estimates.
Accessed 9 Jul 2020 at: wpe.wetlands.org
Wickham, H. 2016. Ggplot2: Elegant Graphics for Data
Analysis. Springer-Verlag, New York, USA. Accessed 20
Sep 2020 at:https://ggplot2.tidyverse.org
Yeap, C.A., A.C. Sebastian & G.W.H. Davidson. 2007.
Directory of Important Bird Areas in Malaysia: key sites
for conservation. (MNS Conservation Publication No. 8).
Malaysian Nature Society, Kuala Lumpur, Malaysia.
Yong, D.L., A. Jain, C.-Y. Choi, M. Iqbal, N. Crockford, J.
Provencher & S. Millington. 2018. Challenges and oppor-
tunities for transboundary conservation of migratory
birds in the East Asian-Australasian yway. Conservation
Biology 32: 740–743.
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