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Autumn 2003 raptor migration at Chumphon, Thailand: a globally significant raptor migration watch site

Authors:
  • Hawk Mountain Sanctuary

Abstract

Daily counts of migrating raptors were made on 43 days between 27 September and 9 November 2003 near the city of Chumphon in south-east Thailand. Overall, 170,665 migrating raptors of 15 species were counted during 378 hours of observation (452 birds/hour).The counts of five raptor species (Black Baza Avecida leuphotes ,O riental Honey-buzzard Pernis ptilorhyncus, Eastern Marsh Harrier Circus spilonotus, Chinese Sparrowhawk Accipiter soloensis and Grey-faced Buzzard Bustatur indicus) represent some of the highest totals reported to date. Winds from the north to west and cloud cover were positively associated with the number of raptors seen. We recommend that counts be continued at Chumphon in the future and that the site is used to promote raptor conservation in Thailand.
INTRODUCTION
Fifty-five species of diurnal raptors occur in Thailand,
of which 41 undertake partial or long-distance
movements within or through the country (Zalles and
Bildstein 2000, Robson 2002). Thailand is an impor-
tant migration crossroads for east Asian raptors that
over-winter in Malaysia, Singapore, Bali, Sumatra, and
elsewhere in Indonesia. Since the 1960s, biologists
have looked for areas on the Thai-Malay Peninsula
from which to count migrating raptors. Most prior
research comes from field studies in Malaysia
(Medway and Nisbet 1965, Wells 1990, Wells 1999).
Raptor migration in Thailand remains largely undocu-
mented (see Melville and Fletcher 1982, Lekagul et al.
1985, Bijlsma 1996).
In September 1997, large numbers of migrating
raptors were observed by C. Nualsri near the town of
Chumphon, south-east Thailand (Fig. 1). Subsequent
observations confirmed significant movements of
raptors through the region each autumn. This impor-
tant coastal-plain bottleneck in peninsular Thailand
had been previously recognised from observations
made approximately 100 km north of Chumphon by
Melville and Fletcher (1982) and by P. D. Round and
others in 1983–1994 at Kui Buri, c.5 km east of Ban
Yang Chum near the Gulf of Thailand (see Zalles and
Bildstein 2000). This apparently important flyway has
not been well studied, however, and the relative
numbers of raptors using it in spring and in autumn,
the origin of the migrants, and their ultimate destina-
tions, are all largely unknown (Lane and Parish 1991,
Zalles and Bildstein 2000, Nijman 2001a).
In 2003, we conducted a six-week count to deter-
mine the phenology of these movements including the
numbers of species and individuals involved, together
with the daily and seasonal timing of the migration.
METHODS
Chumphon (10
o
28
N 99
o
13
E; sea level) is a town
(population: 16,000) on the eastern coastal plain of
southern Thailand, 460 km south-west of Bangkok,
FORKTAIL 20 (2004): 49–54
Autumn 2003 raptor migration at Chumphon,
Thailand: a globally significant raptor
migration watch site
ROBERT DECANDIDO, CHUKIAT NUALSRI, DEBORAH ALLEN and
KEITH L. BILDSTEIN
Daily counts of migrating raptors were made on 43 days between 27 September and 9 November 2003 near the city of Chumphon
in south-east Thailand. Overall, 170,665 migrating raptors of 15 species were counted during 378 hours of observation (452
birds/hour).The counts of five raptor species (Black Baza Avecida leuphotes,Oriental Honey-buzzard Per nis ptilorhyncus, Eastern Marsh
Harrier Circus spilonotus, Chinese Sparrowhawk Accipiter soloensis and Grey-faced Buzzard Bustatur indicus) represent some of the
highest totals reported to date. Winds from the north to west and cloud cover were positively associated with the number of raptors
seen. We recommend that counts be continued at Chumphon in the future and that the site is used to promote raptor conservation
in Thailand.
Figure 1. Location of Chumphon, Thailand (1) relative to
other important migration watch sites in East Asia: Beidaihe,
China (2); Uchiyama-toge, Nagasaki, Japan (3);
Kohyamacho, Kagoshima, Japan (4); Miyako Islands
(Ryukyus), Okinawa, Japan (5); Selangor Plain, Malaysia (6);
and Bali Barat National Park, Indonesia (7).
Forktail 20 (2004)
550 km north of Malaysia, and 55 km east of
Myanmar. The north-south Bilauktaung range of
mountains 35 km to the west funnels many diurnal
bird migrants through this 30-km wide coastal plain
adjacent to the Gulf of Thailand (Wells 1999, Zalles
and Bildstein 2000). Migration was observed at a site
(10
o
28.40
N 99
o
13.26
E) in an unprotected freshwater
marsh 4.6 km east-north-east of Chumphon, and
approximately 2 km north-east of the coastal highway
at Ban U-Tapao,Tha Yang subdistrict, Muang district,
Chumphon province. The marsh is composed prima-
rily of emergent aquatic plants, including sedges Carex
spp., cat-tails Typha spp., and common reed Phragmites
australis.Vegetation averages less than 1.5 m high, and
it does not prevent observation of low-flying raptor
migrants. On fair days, it is possible to see 10 km to the
north-east, 3 km to the east and west, and about 1 km
to the south.
The weather in late summer–early autumn is deter-
mined by the interaction between a monsoonal
low-pressure system in the Pacific Ocean to the east,
and a high pressure system in the Andaman Sea to the
west. In September and early October, the high
pressure system prevails, and most winds are from the
west or north-west. By mid-October, the low pressure
system predominates, and winds are easterly. Heavy
rain is common in mid-October as low pressure
replaces high pressure in the region. The bulk of the
migration occurs during the ‘south-west’
(April–October) rather than ‘north-east’ monsoon
(November–January).
We counted migrants from 27 September to 11
November, which correspond to the peak of the raptor
movements in the area. Migrating raptors were
counted by RDC using 10x binoculars, assisted at
times by CN and DA. Count protocols followed those
described in Bildstein and Zalles (1995). Most obser-
vations began at 07h00 local time and usually ended at
17h00. Most raptors (>95%) were readily identified to
species using Porter et al. (1986), Clark (1999),
Jeyarajasingham and Pearson (1999),Wells (1999) and
Robson (2002). Weather conditions (wind speed,
barometric pressure, temperature, humidity) were
monitored hourly throughout the day with a hand-held
Kestrel 4000 ‘weather station’ (Nielsen-Kellerman
corporation, U.S.A.). Wind direction was determined
with a compass.
Observers scanned primarily north for approaching
migrants. An individual was considered a migrant if it
passed north-to-south across an imaginary east-west
50 ROBERT DECANDIDO et al.
Figure 2. Daily totals of raptors counted on migration at
Chumphon, Thailand, autumn 2003.
Ta ble 1. Raptor species, numbers counted, and seasonal peaks at Chumphon,Thailand, in autumn 2003.
O
SPREY Pandion haliaetus 31 (<1%) 5 Oct–9 Nov 18 Oct (6)
B
LACK BAZA Aviceda leuphotes 68,219 (40%) 21 Oct–9 Nov 23 Oct (42,046)
O
RIENTAL HONEY-BUZZARD Per nis ptilorhyncus 15,972 (9%) 10 Sep– 9 Nov 1 Oct (3,021)
B
LACK KITE Milvus migrans 124 (<1%) 27 Sep–9 Nov 10 Oct (29)
E
ASTERN MARSH HARRIER Circus aeruginosus spilonotus 178 (<1%) 27 Sep–9 Nov 23 Oct (25)
P
IED HARRIER Circus melanoleucos 11 (<1%) 27 Sep–2 Nov
C
HINESE SPARROWHAWK Accipiter soloensis 57,667 (34%) 27 Sep–9 Nov 11 Oct (10,389)
J
APANESE SPARROWHAWK Accipiter gularis 5,811 (3%) 9 Sep–9 Nov 23 Oct (606)
G
REY-FACED BUZZARD Butastur indicus 14,962 (9%) 14 Oct–9 Nov 23 Oct (9,985)
C
OMMON BUZZARD Buteo buteo 10 (<1%) 8 Oct–9 Nov
G
REATER SPOTTED EAGLE Aquila clanga 3 (<1%) 18 Oct–23 Oct
B
OOTED EAGLE Hieraaetus fasciatus 8 (<1%) 10 Oct–5 Nov
C
OMMON KESTREL Falco tinnunculus 4 (<1%) 18 Oct–23 Oct
E
URASIAN HOBBY Falco subbuteo 3 (<1%) 15 Oct–24 Oct
P
EREGRINE FALCON Falco peregrinus 8 (<1%) 8 Oct–18 Oct
U
NIDENTIFIED HARRIER Circus spp. 66 (<1%)
U
NIDENTIFIED ACCIPITER Accipiter spp. 1,168 (1%)
U
NIDENTIFIED BUZZARD Buteo spp. 5 (<1%)
U
NIDENTIFIED FALCON Falco spp. 4 (<1%)
U
NIDENTIFIED RAPTORS 6,411 (4%)
Total 170,665 23 Oct (56,101)
Species Number counted Dates seen Seasonal peak
(% of total migrants) (highest count)
line at the watch site, and continued south out of sight.
No attempt was made to determine the relative
proportion of males versus females, or of adults versus
immatures.Totals for large flocks (>300 individuals) of
Black Baza Avecida leuphotes, Chinese Sparrowhawk
Accipiter soloensis and Grey-faced Buzzard Bustatur
indicus were estimated to the nearest 25 individuals.
RESULTS
In total, 170,665 raptors of 15 species were counted
migrating during 378 hours of observation (averaging
452 birds/hour;Table 1). Black Baza was the common-
est migrant (68,219 individuals), representing 40% of
the 163,020 individuals identified to species (Table 1).
The largest flock of this species, estimated at 1,300
birds, passed on 23 October. Chinese Sparrowhawk
(57,667 individuals) made up 34% of all individuals
identified, with 550 individuals in one flock on 11
October. We also observed large numbers of Grey-
faced Buzzard (14,962 individuals; 9%; largest flock =
500 individuals on 23 October) and Oriental Honey-
Buzzard Pernis ptilorhyncus (15,972 individuals; 9%;
largest flock = 91 individuals on 7 October).
The highest single day count was 56,101 individu-
als of ten species on 23 October (Fig. 2). A peak of 11
species was observed on 18 October.There were differ-
ences between species in their seasonal pattern of
migration (Fig. 3). Of the five commonest species,
Chinese Sparrowhawk and Oriental Honey-buzzard
migrated through the area primarily before mid-
October, Grey-faced Buzzard and Black Baza migrated
primarily in late October, and Japanese Sparrowhawk
Accipiter gularis migrated through the area throughout
the autumn (Fig. 3).
Raptors at Chumphon typically migrated through-
out the day, sometimes from shortly after 07h00 until
shortly before 18h00 (Fig. 4). On most days,
movements of Chinese Sparrowhawk and Grey-faced
Buzzard peaked at 09h00–10h00. Oriental Honey-
Buzzard migration peaked at 10h00–11h00. About half
of all raptors (53%) were seen from 09h00 to12h00
(Fig. 4). On most days, counts decreased thereafter
until 15h00–16h00, when they again increased. Most
of the migrants (72%) were seen when cloud cover
exceeded 70%. Between 12h00 and 15h30, raptors
frequently flew at heights above 600–800 m, especially
if winds were <8km/hour. Entire flocks of certain
species (Chinese Sparrowhawk, Grey-faced Buzzard),
and individuals of other species (Oriental Honey-
buzzard, Japanese Sparrowhawk) sometimes
disappeared into the bases of clouds when they soared
in thermals. At 19h25 on 1 October 2003, CN
observed a flock of about 50 Chinese Sparrowhawks
entering a night-time roost in a coconut Cocos nucifera
grove near the watch site. Several species, including
Black Baza, Chinese Sparrowhawk, and Japanese
Forktail 20 (2004) 51Autumn 2003 raptor migration at Chumphon, Thailand
Figure 3. Number of (a) Black Baza, (b) Oriental Honey-
buzzard, (c) Chinese Sparrowhawk, (d) Japanese
Sparrowhawk and (e) Grey-faced Buzzard counted at
Chumphon, Thailand, in autumn 2003.
Forktail 20 (2004)
Sparrowhawk roosted in coastal mangrove forests
10–15 km north of the site.
We considered four species (Black Baza, Oriental
Honey-buzzard, Chinese Sparrowhawk and Grey-
faced Buzzard) to be obligate flocking migrants at the
site (sensu Kerlinger 1989). We also observed mixed-
species flocks of Grey-faced Buzzard and Black Baza,
and of Japanese and Chinese Sparrowhawk.
Individuals of several other species (e.g. Osprey
Pandion haliaetus, Black Kite Milvus migrans and
Greater Spotted Eagle Aquila clanga) were sometimes
seen in groups of two or more individuals. Several
researchers (Ash 1993, Wells 1999, Nijman 2001b,
Robson 2002) have noted flocks of Japanese
Sparrowhawk in South-East Asia, but we did not see
single-species flocks of this species at Chumphon.
More raptors were counted at the site on winds
from the west or north-north-west than the east or
south (P² = 41.7, P<0.05). From 27 September to 25
October, winds were typically light to moderate for the
entire day. Later in the season, early morning westerly
or variable winds shifted to on-shore, easterly winds by
about 10h00. Raptors were then seen primarily flying
north-to-south-west of the site, and after noon few
raptors were observed passing over the site itself.
Three additional raptor species (Black-shouldered
Kite Elanus caeruleus, Brahminy Kite Haliastur indus,
and White-bellied Sea Eagle Haliaeetus leucogaster)
were resident in and around Chumphon and were not
counted. Non-raptors seen migrating, or apparently
migrating, at the watch site included Little Cormorant
Phalacrocorax niger, Grey Heron Ardea cinerea, Purple
Heron Ardea purpurea,Oriental Pratincole Glareola
maldivarum, Grey-headed Lapwing Vanellus cinereus,
Pale-capped Pigeon Columba punicea, House Swift
Apus affinis, Asian Palm Swift Cypsiurus balasiensis,
Fork-tailed Swift Apus pacificus, Blue-throated Bee-
eater Merops viridis,Blue-tailed Bee-eater Merops
philippinus, Barn Swallow Hirundo rustica, Red-rumped
Swallow Hirundo daurica, Sand Martin Riparia riparia,
Ashy Minivet Pericrocotus divaricatus and Black Drongo
Dicrurus macrocercus (see DeCandido et al.2004).
DISCUSSION
Our counts demonstrate a significant autumn
movement of soaring raptors at Chumphon, Thailand.
The number of raptor species observed (15), the
number of individuals counted (170,665), and the
average number of raptors counted per hour (452) are
the highest totals reported to date in South-East Asia.
The numbers of five species (Black Baza, Oriental
Honey-buzzard, Eastern Marsh Harrier, Chinese
Sparrowhawk, and Grey-faced Buzzard) appear to be
among the highest single-season totals reported in Asia
(Medway and Nisbet 1964, Lin and Lin 1986,
Severinghaus 1991, Ash 1993, Kugai 1996, Chong
2000, Nitani 2000, Williams 2000, Nijman 2001b,
Tordoff 2002; see Table 2). Based on our observations,
we estimate that as many as 500,000 raptors may
migrate south over Chumphon each year between
52 ROBERT DECANDIDO et al.
Ta ble 2. Maximum autumn counts of raptors at sites in East Asia for the six most common migrants seen in autumn 2003 at Chumphon, Thailand. (See
Fig. 1 for locations).
B
LACK BAZA Avecida leuphotes 68,219 2003 Chumphon, Thailand This study
O
RIENTAL HONEY-BUZZARD Per nis ptilorhyncus 121,000 1963 Selangor Plain, Malaysia Medway and Nisbet (1964),Wells (1999)
E
ASTERN MARSH HARRIER Circus aeruginosus spilonotus 576 1986 Beidaihe, China Williams (2000)
C
HINESE SPARROWHAWK Accipiter soloensis 439,276 1999 Uchiyama-toge, Nagasaki, Japan Nitani (2000), Chong (2000)
J
APANESE SPARROWHAWK Accipiter gularis 7,835 1984 Bali Barat, Indonesia Ash (1993)
GREY-FACED BUZZARD Butastur indicus 31,784* 1999 Kohyamacho, Kagoshima, Japan Nitani (2000), Chong (2000)
*Unpublished data indicate that a higher count was made at the Miyako islands (Ryukyus), Okinawa, Japan: 53,575 individuals in autumn 1980; data from
1973–2003 give an annual mean of 27,859 individuals (Y. Nitani in litt. 2004).
Species Max. Year Location Source
count
Figure 4.Pattern of raptor migration through the day (birds/hour) at Chumphon,Thailand, in autumn 2003.
August and early December.This makes Chumphon a
watch site of global significance (Yosef et al. 2000,
Zalles and Bildstein 2000).
Small numbers of two other raptors (nine Steppe
Eagles Aquila nipalensis and two Imperial Eagles Aquila
heliaca) were seen migrating in early November at a
location c.8 km west of the site (not included in
Table 1). Further research may determine if several
other raptor species that are regarded as migrants in
Thailand (Hen Harrier Circus cyaneus,Western Marsh
Harrier C. aeruginosus aeruginosus, Shikra Accipiter
badius and Eurasian Sparrowhawk A. nisus) also
regularly pass through the area.
The raptors counted at Chumphon are thought to
follow at least two migration routes in East Asia: (a) an
Eastern Inland Corridor that extends from south-
eastern Siberia through eastern China and Indochina
(Laos, northern Vietnam, northern Thailand), south
through the Thai-Malay Peninsula; and (b) a Coastal
Pacific Corridor that extends from north-eastern
Siberia, Amurland, and Ussuriland through coastal
China, south into Indochina and the Thai-Malay
Peninsula (McClure 1998, Zalles and Bildstein 2000).
Movements along these corridors are poorly under-
stood, and additional study is needed to determine the
routes used by different raptors in the Far East (Ellis et
al. 1990, Lane and Parish 1991, Severinghaus 1991,
Ash 1993, Chong 2000, Nitani 2000, Williams 2000,
Nijman 2001a,Tordoff 2002). Satellite-tracking of two
Oriental Honey-buzzards in autumn 2003 showed that
they left their breeding grounds in Japan in mid-
September, crossed to mainland China and headed
south-west across Indochina, then south through the
Thai-Malay Peninsula to Sumatra (H. Higuchi in litt.
2004). Further studies may reveal the extent to which
outbound raptors including Oriental Honey-buzzard,
Chinese Sparrowhawk and Grey-faced Buzzard, follow
the Oceanic Pacific Corridor, before heading west to
the mainland, and south into Malaysia and Indonesia.
Weather conditions had a major influence on the
number of raptors migrating. Significantly more
raptors were seen when winds were from the north-
west quadrant than when winds were from the
south-east quadrant. Raptors seemed to ‘drift’ to the
coast with westerly winds when skies were overcast and
when strong thermals were lacking. With moderate
westerly winds, as many as 10% of the migrants passed
approximately 2 km to the east of the site along the
Gulf of Thailand. On 23 October, we counted 56,101
migrants during overcast skies and light to moderate
west to north-west winds. On that day the area <7 km
north and west of the watch site was free of precipita-
tion, but it was raining throughout much of central and
northern Thailand. Although steady rain at the watch
site ended raptor migration there, we believe that local
rains simply diverted migrants around the precipitation
cell. Observers in the Neotropics have also noted
migration in light or intermittent rain and overcast
skies (Bildstein and Saborio 2000).
Recommendations
The raptor migration at Chumphon affords an excep-
tional opportunity for research and education. We
recommend a season-long autumn count by experi-
enced observers from mid-August to late November, as
well as exploratory partial season spring counts in mid-
March through mid-May. Several (3–4) observers
would be needed in order to reduce observer fatigue.
Training of local people to assist with counts is needed.
Consideration should be given to a coordinated
transect count in the region, including searching for
large overnight roosts. There is no comprehensive
guide to flight identification of raptors for this part of
the world, and we suggest that printed and on-line
guides to the different raptors of East Asia be devel-
oped as quickly as possible. A poster depicting raptor
diversity in Thailand and South-East Asia could serve
as a keystone visual aid providing information about
Asian raptors. A children’s colouring book of the
common birds of Thailand with basic information
about urban and suburban raptors would create
interest at the grassroots level.
ACKNOWLEDGEMENTS
We sincerely appreciate the encouragement and thoughtful advice of
Phil Round of Mahidol University. Uthai Treesucon of Bangkok
provided many helpful ideas and suggestions to the raptor watch
team. We thank Hiroyoshi Higuchi of the University of Tokyo for
sharing some unpublished information. Yasunori Nitani of the Asia
Raptor Research and Conservation Organization (ARRCN)
provided migration count data for Chinese Sparrowhawks and Grey-
faced Buzzards in Japan. Anne Arrowsmith designed the map. We
deeply appreciate the kindness shown to us by our colleagues of the
Malaysian Nature Society including Laurence and Audrey Poh,
Cheang Kum Seng, Liew Siew Lan and Ooi Beng Yean, Regina
Anthony and Chiu Sein Chong as well as Lim Aun Tiah and Lim
Kim Chye. Desmond Allen provided GPS coordinates of the site.
David Wells read a version of this manuscript and provided helpful
comments. Those wishing to observe raptor migration at Chumphon
should contact Chukiat Nualsri (bntern@chaiyo.com) for details
about how to reach the watch site, and the annual Raptor Watch
festival usually held in the second week of October. Our research was
supported by grants from the Bobolink Foundation and the Oriental
Bird Club, and by a Hawk Mountain Sanctuary Project Soar Award.
This is Hawk Mountain Sanctuary Contribution to Conservation
Science number 108.
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54 ROBERT DECANDIDO et al.
Robert DeCandido, Acopian Center for Conservation Learning, Hawk Mountain Sanctuary, 410 Summer Valley Road,
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... For the past 15 yr, the migration counts at Kenting ranged from 94,000 to 245,000 individuals of 20 migratory raptor species (hawks, ospreys, and falcons; Chang and Tsai 2018). Kenting is the second largest flight corridor in Southeast Asia, following Khao Dinsor in Thailand (Decandido et al. 2004, Nualsri and Decandido 2010, Limparungpatthanakij et al. 2019; however, hawks that pass Thailand take a continental flyway, rather than the over-water route, to their wintering grounds on tropical islands. ...
... Assuming the data from both watchsites are reliable, it would be interesting to explore why the number of Chinese Sparrowhawks was higher at Khao Dinsor in 2015 and 2016. Conversely, the Oriental Honey-Buzzard and Japanese Sparrowhawk are relatively rare at Kenting compared to watchsites in Thailand (Decandido et al. 2004, Limparungpatthanakij et al. 2019). Many Oriental Honey-Buzzards from Japan apparently take an indirect route via the continental flyway to their wintering habitats on Indonesian Islands (Shiu et al. 2006, Yamaguchi et al. 2008. ...
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Diurnal raptors were counted during their southward migration in autumn of 2019 at Kenting National Park, southern Taiwan, an important hawkwatch site along the East-Asian Oceanic Flyway. Observations were conducted from 1 September to 31 October 2019 in the morning hours, but the observation period was extended to 1400 H whenever large numbers of raptors passed the site before noon. A total of 329,559 individuals of 14 migratory raptor species was recorded. The Chinese Sparrowhawk (Accipiter soloensis) and Gray-faced Buzzard (Butastur indicus) made up 78.3% (257,971 birds) and 21.6% (71,045 birds) of the total, respectively. The number of Chinese Sparrowhawks increased significantly when we extended the survey duration from 1200 H to 1400 H (paired t-test, t = 2.44, P = 0.04), but the number of Gray-faced Buzzards did not (t = 1.94, P = 0.09). Thus, Chinese Sparrowhawks may continue passing the site en route to the Philippine Islands in the afternoon hours, whereas Gray-faced Buzzards usually stop migrating in early afternoon, at least under certain conditions. How prevailing wind conditions along the East-Asian Oceanic Flyway in autumn shape the different migratory strategies of these two hawk species requires further study.
... Although raptor migration and associated persecution are widely reported in North America and Europe, these topics are still overlooked in Asia, especially in the East-Asian continental flyway that hosts more than one million migrating raptors (Bildstein 2006, but see Williams et al. 1992, DeCandido et al. 2004, Germi 2005, including many threatened species (McClure et al. 2018). To reach their wintering grounds in the Indochina Peninsula and further in South-east Asia, migrating raptors funnel through south-west China, confined by the Beibu Gulf to the south-east and high mountain ranges in Yunnan Province and Myanmar to the north-west (Bildstein 2006, Bildstein andJuhant 2017). ...
... The migration route taken by AF is particularly interesting since it is among the longest route known and passes through several of the most difficult geographical barriers (Bildstein 2006, Bildstein andJuhant 2017). Ornithological records from South-east Asia showed a broad yet defined corridor circumventing the Himalayas and the adjacent high mountains: Flocks of AF can be observed at various locations in northern Indochina Peninsula and south-west China, but few can be found further south in Central Thailand (Clement and Holman 2001, DeCandido et al. 2004, Dixon et al. 2011, Tordoff 2002. In Hong Kong, about 500 km east of Guantouling, records of AF are also scarce (Viney et al. 2005). ...
Article
South-west China, particularly between the Himalayas and the Beibu Gulf, constitutes an important corridor for migratory raptors along the East-Asian continental flyway. However, a lack of ornithological assessment and the common practice of illegal hunting in this region emphasize the need for research and conservation actions. To investigate the ecology of migration and scale of persecution, we launched one of the first citizen-science projects in mainland China to record southward-migrating raptors and hunting gunshots from 2015 to 2019 on Guantouling, a well-known raptor site in South-west China. A total of 42,891 raptors were recorded, belonging to 30 diurnal raptor species. Grey-faced Buzzard Butastur indicus , Oriental Honey Buzzard Pernis ptilorhynchus and Amur Falcon Falco amurensis were the three most abundant species recorded. The bulk of Grey-faced Buzzard and Amur Falcon migrated through Guantouling from mid-October till early November, while Oriental Honey Buzzard migrated throughout October and early November. Precipitation slowed down migration significantly while increasing cloud cover was favoured by the three most abundant species. We found hunting mostly occurred in the afternoon, coinciding with an increasing number of Oriental Honey Buzzard, which may become a major victim of hunting. It is thus suggested to prioritize peak raptor migration period for law enforcement actions, especially on cloudy days and after passage of cold fronts, when Oriental Honey Buzzards and other species are likely to migrate. The annual counting scheme on Guantouling is not only an ecological survey, but also an effective way of engaging the public to counter raptor persecution.
... Due to relatively small landmass, the average national proportion of migratory species covered by each radar is usually higher in island countries/regions and peninsulas, such as South Korea (86% of all migrants), the Philippines (81%), Taiwan (73%), and Malaysia (73%). East Asian migrants often congregate at these narrow land corridors to minimize the lengths of sea crossings during migration, leading to large concentration of birds during the migration season (DeCandido et al., 2004(DeCandido et al., , 2010Nourani et al., 2018;Sugasawa & Higuchi, 2019). A prime example would be raptors that breed in North Asia and migrate via the island chains of Japan, Taiwan, and the Philippines (commonly referred to as the East-Asian Oceanic Flyway), often in tens of thousands of individuals that form large flocks visible on radar screens (Chen et al., 2022;Concepcion et al., 2017;Sun et al., 2010). ...
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Each year, billions of birds migrate across the globe, and interpretation of weather radar signals is increasingly being used to document the spatial and temporal migration patterns in Europe and America. Such approaches are yet to be applied in the East Asian-Australasian Flyway (EAAF), one of the most species-rich and threatened flyways in the world. Logistical challenges limit direct on-ground monitoring of migratory birds in many parts of the EAAF, resulting in knowledge gaps on population status and site use that limit evidence-based conservation planning. Weather radar data have great potential for achieving comprehensive migratory bird monitoring along the EAAF. In this study, we discuss the feasibility and challenges of using weather radar to complement on-ground bird migration surveys in the flyway. We summarize the location, capacity and data availability of weather radars across EAAF countries, as well as the spatial coverage of the radars with respect to migrants' geographic distribution and migration hotspots along the flyway, with an exemplar analysis of biological movement patterns extracted from Chinese weather radars. There are more than 430 weather radars in EAAF countries, covering on average half of bird species' passage and non-breeding distributions, as well as 70% of internationally important sites for migratory shorebirds. We conclude that the weather radar network could be a powerful resource for monitoring bird movements over the full annual cycle throughout much of the EAAF, providing estimates of migration traffic rates, site use, and long-term population trends, especially in remote and less-surveyed regions. Analyses of weather radar data would complement existing ornithological surveys and help understand the past and present status of the avian community in a highly threatened flyway.
... There are relatively few hawk watch sites where autumn migration is regularly monitored on this flyway (Zalles and Bildstein 2000), of which the best-known is at Khao Dinsor, Chumphon Province, southern Thailand, where .200,000 migrant hawks are recorded annually (Zalles and Bildstein 2000, DeCandido et al. 2004, Limparungpatthanakij et al. 2019. ...
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Identifying the drivers of shifts in the abundance of wildlife species has been a central focus of conservation ecology recently. With growing concern about the impacts of global environmental change on biodiversity patterns, ecologists are challenged to better understand the relationships between species' abundance and various environmental factors. Using raptor count data collected following a standardized protocol at Khao Dinsor, southern Thailand, in 2015 and 2016, we characterized the seasonal timing and identified weather associations of the visible migration of representative species, namely the Black Baza (Aviceda leuphotes), Chinese Sparrowhawk (Accipiter soloensis), and Oriental Honey-Buzzard (Pernis ptilorhynchus). We explored the associations of their daily total counts with local weather variables. We found that the magnitude of their migration within the season was linked with the prevailing meteorological conditions. In general, daily counts of all three species were positively associated with predominant wind patterns. Air temperature was positively associated with the daily counts of species that migrated early in the season (Chinese Sparrowhawk and Oriental Honey-Buzzard). Barometric pressure was negatively associated with the daily counts of species whose migration window coincides with the shift in monsoon season (Black Baza and Oriental Honey-Buzzard). These results provide us with a better understanding of the drivers of migration patterns at a representative monitoring site on a globally important and heavily used flyway. They may be useful for making better inferences and predictions on the population trajectories of migrating raptors in future environmental change scenarios.
... Raptors using the East Asian Continental Flyway, which extends from Siberia and China through mainland South-east Asia to Indonesia (Bildstein, 2006;Newton, 2008), utilise the Thai-Malay Peninsula as a land bridge between Indochina and the islands of the Greater and Lesser Sundas, on their biannual migrations (Medway, 1976). The migration of raptors on this route has been recognized in the southern Thai provinces since at least the mid-1980 s (Melville and Fletcher, 1982;Lekagul et al., 1985) and regular counts have taken place since 2003(DeCandido et al., 2004. Over 150,000 Chinese Sparrowhawks and c. 20,000 Japanese Sparrowhawks A. gularis pass the principal watchpoint, Khao Dinsor, Chumphon province, on their southward migration each autumn, together with three congeners (several thousand Shikras A. badius, < 100 Besras A. virgatus and a few Eurasian Sparrowhawks A. nisus; Limparungpattanakij et al., 2019). ...
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Understanding the movements and requirements of individual species within bird migration flyways is of crucial conservation importance, especially along the East Asian Flyway considering the immense human pressure on the environment and habitats. We attached satellite transmitters to females of four Chinese Sparrowhawks Accipiter soloensis and four Japanese Sparrowhawks A. gularis mist-netted on their southward passage through Thailand. The Chinese Sparrowhawks wintered across a c. 3000 km-wide longitudinal span from Sumatra to Timor-Leste, spending 84–173 days on their wintering grounds before returning to breeding grounds in south and east China. Two were tracked for complete migration cycles of 14,688 and 9694 km, respectively. Three of four Japanese Sparrowhawks were tracked to wintering grounds in Sabah, Kalimantan, and the Bangka Belitung Islands where they spent 168–173 days before returning north. The Bangka Belitung winterer was tracked to presumed breeding grounds in Amurskiy Oblast, eastern Russia, traveling 7757 km in 53 days. Daily flights varied widely up to c. 800 and 382 km for Chinese and Japanese Sparrowhawk, respectively. With few individuals sampled, no significant differences were found within or between species, in the daily distances flown during southward or northward journeys. However, Japanese Sparrowhawks made fewer stopovers suggesting they traveled faster on northward migration than Chinese Sparrowhawks. Movements during the wintering and nesting periods were mostly confined to areas of less than 23 km², although one wintering Chinese Sparrowhawk used an area of over 600 km². Further work is needed to improve knowledge of the annual cycles of these and other migratory East Asian raptors and how they might differ among age- and sex-classes within species.
... The peninsular mountain spine here divides the narrower, more mountainous Thai provinces of Ranong, in the west, from the broader (now largely deforested) coa st a l pl a i n of Chu mphon province in the east. The most recent (post-2000) observations of the migration of raptors and other diurnal migrants were initiated by CN in Chumphon, and by other observers in Prachuap Khiri Khan province further north (DeCandido et al. 2004a, 2004b, 2008, Lorsunyaluck et al. 2008. ...
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Khao Dinsor, Chumphon Province, on the Thai-Malay Peninsula, is a globally important monitoring site for southbound migratory raptors using the East Asian Continental Flyway. We report the progress of our observations, in which 35 species of resident and migratory raptors were recorded during successive autumns in 2010–2016. During two years of systematised coverage, totals of 397,285 individuals of at least 24 migratory raptor species were counted during late August to mid November 2015 and 791,229 individuals of 22 species in 2016. The first records of Bonelli’s Eagle (Aquila fasciata) and Rufous-winged Buzzard (Butastur liventer) for the Thai-Malay Peninsula and previously unreported significant migratory passages of Jerdon’s Baza (Aviceda jerdoni), Crested Serpent Eagle (Spilornis cheela), Shikra (Accipiter badius) and Besra (A. virgatus) are documented.
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The Black Drongo Dicrurus macrocercus is a medium- sized passerine of temperate and tropical Asia. It breeds in south-east Iran, Afghanistan, India, south-east Tibet, and from northern China discontinuously south through south-west Thailand, to Bali and Java. Northern populations migrate, wintering at lower altitudes and latitudes, reaching as far south as central India in the west, and Malaysia and Sumatra in the east, where they occur in tropical savanna, grassland and agricultural areas (Jeyarajasingham and Pearson 1999). Little has been published about Black Drongo migration. Historically, the species was considered an 'extremely abundant' migrant in September at Beidaihe, China, occurring in 'huge noisy parties' (La Touche 1920). In an autumn migration survey of the same area from 1986-1990,Williams (2000) counted a maximum of 452 in 1986, but only 196 in 1990. Melville and Fletcher (1982) counted 1,444 flying west in less than two hours of observation on 14 October 1980 near Bangkok, Thailand. Numbers migrating through, and wintering in, Thailand appear to have declined in recent years (P. Round verbally 2003, D. Wells in litt. 2004). As part of a study of raptor migration through southern Thailand in autumn 2003 (DeCandido et al. 2004), we also counted the number of migrant Black Drongos passing the watch site.
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The migration of northern migrant raptors was studied at three sites in the western half of the island of Java, Indonesia during the northern autumns of 1998 and 1999. During 58 days of observation 4716 migrants were observed, 3087 of which could be identified to species level. The migrants comprised six species, i.e. Chinese Sparrowhawk, Accipiter soloensis (2570 birds identified), Japanese Sparrowhawk, A. gularis (245 birds), Oriental Honey-buzzard, Pernis ptilorhyncus (269 birds), Common Buzzard, Buteo buteo (1 bird), Booted Eagle, Hieraaetus pennatus (1 bird), and Marsh Harrier, Circus aeruginosus (1 bird). Both Chinese Sparrowhawks and Japanese Sparrowhawks were frequently observed in large flocks, whereas Oriental Honey Buzzards were more frequently seen singly or in pairs. Between sites, intra-annual variation in proportions of the three most common species identified remained constant over the two-year study period, whereas within one site (Puncak Pass) the proportion of Oriental Honey Buzzards varied from 6 to 10% between years. Migration starts in the third week of September and passage rates (the number of birds passing per hour during 09.01–12.00 hours) of the raptors peaked at the end of October and showed little spatial variation. Migration was observed until the second week of November but it probably continues until mid- or late November. The findings confirm the existence of a large east-south-eastern passage over Java similar to that over the Thai–Malay Peninsula and Bali. Populations migrating through Java originate from northern Asia and most likely have passed over the Thai–Malay Peninsula and Sumatra before reaching Java. An unknown proportion continues on to Bali and/or the Lesser Sunda Islands, but little is known about their final wintering grounds.
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Yosef R., Fornasari L., Giordano A. 2000. Soaring migrants and the 1% principle. Ring 22, 2: 79-84. The conservation of biological biodiversity has taken on international significance – exam-ples of these are: Ramsar Convention, Bonn Convention, Earth Summit in Rio de Janeiro, or Important Bird Areas (IBAs). The IBA is defined as an area, which can be managed for wild-life conservation and provides all the requirements of birds that it is important for, alone or with other sites, at the appropriate season. Among the criteria for IBAs is „1% principle”, which was developed to ensure the protection of important staging areas for waterfowl on their migration routes. We have analysed the numbers of soaring migrants counted at three major bottlenecks of the Palearctic-African migration system during the spring: Gibraltar on the western flyway, Messina on the central flyway, and Eilat on the eastern flyway. Total numbers of raptor spe-cies were – 26 at Gibraltar, 25 at Messina and 39 at Eilat. The comparison of the three re-gions showed that soaring birds mainly cross to Europe and Asia in spring at Eilat. These contain more than 10 raptor species, which can be included in the 1% principle, and some of them even approach or exceed (e.g. Honey Buzzard – Pernis apivorus, Levant Sparrowhawk – Accipiter brevipes, Steppe Eagle – Aquila nipalensis) total breeding populations of Europe, what suggests that large proportions of Asian soaring birds also migrate through Eilat, or that not all the breeding estimates in Europe are accurate. It is imperative that global environmental agencies stress not only the conservation of breed-ing and wintering grounds, but also the conservation of staging areas, which can be critical for the survival of Eurasian bird populations.
Article
In both spring and autumn, millions of migratory birds of prey that breed mainly in North Amer-ica, and overwinter mainly in South America, travel between these two continents via the Mesoamerican Land Corridor, numerically the most important raptor-migration flyway in the world. Although the flight has been well documented at migration bottlenecks in Veracruz, Mexico, and the canal region of Panama, the choreography of raptor migration through most of the 4,000-km corridor is not well understood. Here we report the first counts, rather than estimates, of the spring raptor migration from ten sites in central and southeastern Costa Rica using protocols developed at well-established North American watchsites. Buteo platypterus made up 76%, B. swainsoni 14%, and Cathartes aura 10% of the nine-species, 13,853-bird flight. Our results, which largely confirm earlier estimates of the magnitude, timing, and location of the flight in Costa Rica, suggest that raptors are more likely to migrate in sub-optimal conditions in the tropics than in temperate regions. Although we offer no explanation for this difference, our limited time in the field suggests that both the timing and location of raptor migration are sufficiently well known in Costa Rica to permit the effective study of migrating raptor flight dynamics there, and the establishment of a countrywide monitoring program. Accepted 17 March 2000. Resumen. Durante la primavera y el otoño, millones de aves rapaces migratorias que anidan principalmente en Norteamérica emigran a Sudamérica, viajan entre estos dos continentes a través del corredor de tierra mesoamericano, numéricamente la vía de migración de rapaces más importante en el mundo. Aunque este evento ha sido bien documentado en los cuellos de botella de la migración como Veracrúz, México y la región del Canal de Panamá, la coreografía de la migración de rapaces a través de los 4000 km del corredor no ha sido bien entendida. Reportamos los primeros conteos, mas que las estimaciones, de la migración de primavera de rapaces en diez localidades en el centro y sureste de Costa Rica mediante la utilización de protocolos desarrollados y establecidos por los sitios de conteo norteamericanos. Buteo platypterus repre-sentó el 76% de las observaciones, Buteo swainsoni el 14 %, Cathartes aura el 10 % de las nueve especies y de las 13.853 aves observadas. Nuestros resultados confirman los estimativos previos sobre la magnitud, época y ubicación de la migración en Costa Rica, lo que sugiere que las rapaces emigran bajo condiciones menos óptimas en los trópicos que en las regiones templadas. Aunque no podemos explicar el por que de esta diferencia, nuestro limitado tiempo en el campo sugiere que ambos, la época y ubicación de la migra-ción de rapaces son suficientemente conocidas en Costa Rica para permitir un estudio de la dinámica de vuelo de la migración de rapaces y el establecimiento de un programa de monitoreo a nivel nacional.
Article
There were 82 families of birds represented in this study. The average number of birds ringed per family was 14,197 and per species was 954; however, 19 families accounted for 92.1% of the ringed birds. Among these there were 15 species which made up 59.6% of the total and of these the House Swallow Hirundo rustica made up 24.2%. Forty-four of the families had less than 1500 birds marked per family, totaling only one percent of the birds ringed. The remaining 38 families averaged 30,340 birds per family. The average among the 15 highest species was 46,000. Without the House Swallow the average per species was 29,000. The remaining 1201 species averaged only 389 birds marked per species. When the 19 high families are deducted from the total, the remaining 63 families averaged only 1458 birds per family. (Modified author abstract)
Article
The migration of four northern migrant raptors (Oriental Honey-buzzard Pernis ptilorhyncus, Chinese Sparrowhawk Accipiter soloensis,Japanese Sparrowhawk A. gularis and Common Buzzard Buteo buteo) was studied in the Dieng mountains, Central Java, Indonesia during September-October 1998. Populations migrating through Central Java originate from northern Asia and most likely have passed over the Thai-Malay peninsula and Sumatra before reaching West and Central Java. An unknown proportion continues on to Bali and/or the Lesser Sunda Islands. In all, 68 groups totalling 885 individuals were counted passing by. Ninety-five percent of individuals identified were accipiters, two-thirds of which could be identified to the species level. Passage was directed from WSW-SW to E-ESE, following the alignment of volcanoes on the island. The number of groups was highest during late morning; single individuals were observed significantly more often during the early morning and large (> 25 individuals) groups during the afternoon. Single individuals and small (five or fewer individuals) groups spent significantly less time in the area than large groups. The forests of the Dieng mountains are also used as an overnight stopover and hunting site. Differences in the proportion of the two species of Accipiter identified at Javan and Bali study sites suggests an additional migration route to the one following the Javan mountains. This may follow the eastern edge of the Sunda Shelf. The Dieng mountains qualify as a globally Important Bird Area (IBA) on the grounds of the raptor congregations, as well as because of the presence of globally threatened and restricted range species.
A field guide to the birds of West Malaysia and Singapore
  • A Jeyarajasingham
  • A Pearson
Jeyarajasingham, A. and Pearson, A. (1999) A field guide to the birds of West Malaysia and Singapore. New York: Oxford University Press.
Proceedings and abstracts on the second symposium on raptor research and conservation of Asia
  • Prawiradilaga
Prawiradilaga, ed. Proceedings and abstracts on the second symposium on raptor research and conservation of Asia. Jakarta: Indonesian Committee for the Second Symposium of Asian Raptor Research and Conservation.