Migration at Tanjung Tuan, Malaysia: An Important Spring Bee-eater
Migration Watchsite in South-east Asia.
By Robert DeCandido,
Deborah Allen and Reuven Yosef
This article was originally published in the J. Yamashina Institute
for Ornithology bulletin number 36, 2004 and was kindly submitted
by Robert DeCandido.
Since the 1950s, wintering populations of birds such as Oriental
Honey-buzzards Pernis ptiloryhnchus orientalis have been
known to migrate northeast from Sumatra across the Straits of Malacca
to the west coast of Malaysia (Oakeley 1955, Medway & Nisbet
1965, Wells 1990). It was only recently discovered that a significant
migration of Blue-tailed Bee-eaters Merops philippinus
and Blue-throated Bee-eaters M. viridis also utilized this
same route each spring (Medway & Wells 1976, Fry et al. 1992,
Wells 1999). These bee-eaters are likely returning to breed north
of Indochina, probably in southern China east to Hong Kong (see
Fry et al. 1992, Duckworth et al. 1999). Honey-buzzards
are presumably returning to nest in southeastern Siberia and western
China (McClure 1998, Wells 1999). The magnitude, seasonal duration
and phenology of the migration along this East Asian flyway remain
unclear however (Zalles & Bildstein 2000).
We present data
on bee-eater migration from Tanjung Tuan (Cape Rachado) of peninsular
Malaysia.. The location is a Hawks Aloft Worldwide watchsite near
the town of Port Dickson, 94 km southwest of the capital of Kuala
Lumpur. We discuss use of the site and the bee-eater migration by
biologists for monitoring populations of migratory East Asian birds
(Zalles & Bildstein 2000).
Port Dickson (2o24’N, 101o55’E, sea level) is a small
town on the west coast of Malaysia situated on the Straits of Malacca,
approximately 94 km southwest of Kuala Lumpur. It is located at
the southern end of a south to north range of mountains that presumably
funnels spring migrants north along the western lowlands of the
Malay Peninsula (Medway & Nisbet 1965, Wells 1999). The watchsite
(known locally as Tanjung Tuan and also Cape Rachado) is situated
on the deck of a lighthouse, South of Port Dickson, approximately
3 km west of the coastal highway. The lighthouse is surrounded by
coastal evergreen rainforest in a small, protected forest reserve.
On clear days it is possible to see Sumatra approximately 38 km
across the Straits of Malacca to the southwest. This is the shortest
overwater distance along the Straits from Tanjung Medang on the
island of Pulau Rupat of northwestern Sumatra (Zalles & Bildstein
a lighthouse built by the Dutch in the 18th century, sits atop a
rocky peninsula that extends into the Straits of Malacca on Malaysia's
west coast and provides a 180-degree view to the west, south and
north. The location afforded the best view of arriving bee-eaters
since it overlooked the surrounding forested hills and the Straits
below. The site has also been known as a good place to view the
spring arrival of migrating raptors to mainland Asia (Oakeley 1955,
Medway & Nisbet 1965, Wells 1990). However, it has only recently
been documented that two species of bee-eaters and several species
of swifts and swallows regularly occur there as migrants each spring
(Medway & Wells 1976, Fry et al. 1992, Wells 1999).
of migrating bee-eaters, the Blue-tailed and the Blue-throated,
were counted during early to mid March in 2000 and again in 2001
by two observers (DA and RDC) using 8.5x and 10x binoculars. In
2000, 104 hours of observations were made on 15 days (8 March -
22 March). In 2001, observations were made for 68 hours on 11 days
(2 March - 12 March). Observations usually began at 9-10am local
time since information provided to us by lighthouse staff and observations
by other observers from 1960 to 1983, indicated that minimal diurnal
bird migration occurred at the site before 9am. Observations usually
ended by 4pm each day unless migrants were still being observed
acting primarily as a spotter while photographing the migration;
RDC identified, counted and recorded the number of bee-eaters seen.
Most bee-eaters (70.8%) were readily identified to species (see
Jayarajasingham & Pearson (1999) for descriptions of the two
Merops species). Scientific names follow Clements (2000).
Weather conditions typically were hazy-cloudy with little wind in
the morning till 10am, then becoming clear but humid. On many days
at approximately 10.45am, a 3-12 km/hr sea breeze from west/northwest
would begin. On certain days the wind direction and speed changed
significantly in subsequent hours. Wind direction was measured by
recording the reading shown on the weather vane mounted atop the
lighthouse, and comparing that reading to a hand-held compass with
heading on the lighthouse deck.
Both RDC and
DA scanned mainly to the west across the Straits of Malacca in the
direction of Sumatra from the deck of the lighthouse watchsite.
Bee-eaters of two species, the Blue-tailed and Blue-throated, were
considered migrants if they passed west to east across an imaginary
north-south line at the watchsite, and continued west and out of
sight past the lighthouse and nearby hills. Occasionally, migrants
did not pass the immediate area of the watchsite but continued on
a northeast course over the Straits of Malacca, presumably making
landfall north of the lighthouse. For data analysis, we pooled the
number counted of both bee-eater species along with Merops
individuals we could not identify to species level. We chose this
procedure since we collected migration data in two different years
during two different time frames in March. Also, almost 30% of Merops
individuals we counted in 2000-01could not be identified to species.
It was hypothesized
that more bee-eaters were counted from the watchsite when winds
had a westerly component (NW, W or SW) than when winds were from
other directions (N, NE, E, SE or S). We used a Chi square test
with one degree of freedom to analyze the effect of wind direction
upon the number of bee-eaters making landfall at the Cape.
of several other non-passerine species were also counted in migration
in 2000-01 including five species of raptors: Black Baza (Aveceda
leuphotes), Chinese Goshawk (Accipiter soloensis),
Grey-faced Buzzard (Bustater indicus), Japanese Sparrowhawk
(Accipiter gularis) and Oriental Honey-buzzard (Pernis
ptilorhynchus orientalis). Other species were only noted as
migrants, and no systematic count was made: Fork-tailed Swifts (Apus
pacificus), House swifts (Apus nipalensis) and Pacific
swallows (Hirundo tahitica).
Most bee-eaters counted were migrating west-to-east within 100 m
of the watchsite, and were only observed traveling in loose flocks.
Almost all bee-eaters were first heard calling as part of the flock
before being seen by DA or RDC. Once heard, flocks could then be
located visually and eventually identified to species on most occasions.
Bee-eaters approaching the lighthouse utilized flapping flight interspersed
with glides, and occasionally soaring upwards on air currents generated
by a sea-breeze. Bee-eaters first heard and then observed over the
water typically passed the watchsite within 2-3 minutes. Those making
landfall in the lighthouse area usually arrived at or below eye-level
and circled up on updrafts and continued eastward. Only a few flocks
arrived in flapping-flight above the observers. Occasionally flocks
would stop to rest for up to 10 minutes on exposed branches in the
area of the lighthouse before continuing eastward.
a total of 2,226 bee-eaters of two species (12.9 birds/hour) were
counted during 26 total observation days. These included 1,353 Blue-tailed
Bee-eaters (60.8%), 222 Blue-throated Bee-eaters (10.0%) and 651
unidentified individuals (29.2%). Figure 1 shows the hourly count
of all bee-eater migrants for 2000-01. Most bee-eaters were seen
from 11am-2pm (57.0%) with 11am-12pm being the peak hour. By comparison,
we could not determine the peak of the seasonal migration for either
species from this study since our data were collected in two seasons,
and almost 30% of the migrating bee-eaters could not be identified
1 : Total number of bee-eaters counted in migration by hour
of the day at Tanjung Tuan , Malaysia in March of 2000 and 2001.
highest single-day count of migrating bee-eaters was 326 occurring
on 21st March 2000. The highest hourly total occurred between 1-2pm
also on 21st March when 101 Blue-tailed Bee-eaters were counted.
Significantly higher number sof bee-eaters made landfall at or near
the lighthouse when winds had a westerly (NW to SW) component than
when winds were from other directions (Chi-square=297.9
P<0.05). High totals of bee-eaters arrived at the Cape
on moderate to strong (16-32km/hr) westerly winds as on 17th March
2000 when 254 were counted, and on 19th March 2000 when 248 were
counted. However, on 21st March 2000, the highest total of bee-eaters
(326) in the two seasons of this study was counted on light (<10km/hr)
, East-Northeast to Southeast winds.
Usually at Tanjung
Tuan in spring, once the first flock of bee-eaters arrived at the
Cape, scattered flocks would follow for four to six hours each day
on most days, especially after 10th March. Exceptionally, bee-eater
migration would last for seven (17th March 2000) to eight (21st
March 2000) consecutive hours on a given day. On peak flight days,
the arrival of bee-eaters began at 9-10am (17th March; 20th March;
21st March; all 2000). On only one occasion was a small flock seen
before 9am. Flocks were not usually seen after 4pm, and no bee-eaters
were recorded migrating after 5pm in the two seasons of this study.
Tanjung Tuan on west coastal Malaysia has been known as a significant
migration watchsite for other non-passerine birds such as raptors
that are returning from Sumatra to the Asian mainland (see Oakeley
1955, Medway & Nisbet 1965, Wells 1990). However, only casual
observations have been made of the two Merops species,
the Blue-tailed and Blue-throated Bee-eater, that utilize this same
route each spring (see Medway & Wells 1976, Wells 1999). In
other locations in Southeast Asia, the few published bee-eater migration
accounts present data from single day(s) of observation (see David-Beaulieu
1944, 1949a, 1949b, 1950, Melville & Fletcher 1982, Tizard 1996,
Evans 2001). The only long-term study of migrating bee-eaters comes
from Hong Kong (Carey et al. 2001). Even there data are
based upon a small sample size:: a maximum 30-year aggregate total
of 30-40 individuals counted by week in spring from 1958-1998.
of Tanjung Tuan, a north to south peninsula extending into the Straits
of Malacca, combined with local weather conditions at the watchsite
and in Sumatra, are key factors in determining the large number
of Blue-tailed and Blue-throated Bee-eaters that arrived at the
Cape in migration each spring. The highest hourly totals for bee-eaters
tallied in 2000-01 (Fig. 1) show a peak between 11am-12pm and were
likely correlated with (1) the strong thermals forming over Sumatra
to initiate an overwater crossing, beginning at abotu 10am and (2)
the onset of a sea-breeze. That some flocks were seen in migration
before 11am (Fig. 1) indicates that bee-eaters are less dependent
on thermals than soaring migrants such as broad-winged raptors,
and will utilize active (flapping) flight to a greater degree in
passage. Each of these possibilities warrants additional investigation,
as do the factors that initiate movements of particularly large
numbers of bee-eaters. In any event, conditions in Sumatra probably
play the most important role in determining the extent and timing
of bee-eater migration at the Cape on any given day.
more bee-eaters were counted at the Cape when winds had a westerly
component (NW, W or SW) than when winds were from other directions.
High total numbers of bee-eaters were counted on days when the winds
had a strong (>20km/hr) westerly component. It may be that bee-eaters
are subject to moderate to strong westerly winds, the Cape is the
most propitious point to make landfall since it represents the shortest
overwater crossing from Sumatra. However, more research needs to
be done to determine the precise effects of wind direction and speed
upon the numbers of bee-eaters that make landfall in spring at Tanjung
Also still unclear
is the magnitude of the flight which to date has been censused for
only relatively brief periods of time at Tanjung Tuan in spring
(occasional sigle-day observations made from 1960-83; 15 consecutive
days in 2000; 11 consecutive days in 2001). The 2000-01 migration
data for the Blue-tailed Bee-eaters and the Blue-throated Bee-eaters
are the first attempts to quantify this recently documented Merops
migration at the Cape. Based on our counts, we estimate that approximately
5,000 bee-eaters make landfall at the Cape each spring. We believe
that there will be 15 or so days on which an average of 250 bee-eaters
are observed in migration in March and April, as well as other days
when fewer are counted.
(1990) does not provide any estimates of the number of migrants
of either species in spring at Tanjung Tuan, he does provide information
collected from observers regarding the phenology of spring migration
for these two bee-eater species. Blue-tailed Bee-eaters have been
seen in migration beginning in early March, with a peak in late
March and early April. Few flocks seem to make landfall at Tanjung
Tuan by May, but just north of the lighthouse in Kuala Selangor,
migrant(s) were seen on 25th May (Jeyarajasingham unpublished data,
cited in Wells 1999). By comparison, Blue-throated Bee-eaters have
been noted in migration somewhat earlier (23rd January over Singapore),
with the earliest accepted date at Tanjung Tuan of the 11th February
(Wells 1999). The peak of the Blue-throated migration seems to be
in March through early April with some arrivals until early May.
The latest date of arrival at Tanjung Tuan is 7th May (Wells 1999).
Further north in Hong Kong as part of a long-term study of migrating
birds, observers have also noted a greater proportion of Blue-tailed
vs Blue-throated Bee-eaters each spring, with the peak of the Blue-tailed
Bee-eater migration occurring between 16th April and 8th May (Carey
et al. 2001).
most difficult question to address from the data collected to date
at Tanjung Tuan is where are these north-bound bee-eaters returning
to nest in Asia? The bee-eater migration dates recorded in 2000-01
at Tanjung Tuan accord with those observed in Hong Kong from 1958-98,
and these could represent individuals of the same populations (see
Carey et al. 2001). However, both the Blue-tailed and the
Blue-throated breed over a wide latitudinal range, in different
climates and habitats. It is quite possible there are differences
in overwintering areas used within and outside Sumatra, and differences
in timing of breeding at different latitudes. Migration timing would
therefore be expected to differ between populations. Many populations
of Blue-tailed Bee-eaters are already nesting by February in Indochina,
and it is unlikely that migrants observed in March-April at Tanjung
Tuan are from populations returning to breed in north and central
Thailand, Laos, Cambodia, Vietnam and environs (see Duckworth et
al. 1999, Evans 2001). Further bee-eater migration surveys are needed
at Tanjung Tuan and elsewhere in South-east Asia to determine the
timing and migration phenology of these two species.
We sincerely appreciate the encouragement and thoughtful advice of
members of the Malaysian Nature Society including Laurence and Audrey
Poh, Liew Siew Lan and Ooi Beng Yean, Regina Anthony and Chiu Sein
Chong, Cheang Kum Seng and Lim Aun Tiah. Dr. William Duckworth of
the Wildlife Conservation Society provided the authors with many helpful
ideas and historical references regarding Merops spp. in
Indochina. Jevgeni Shergalin, of the Hawk Mountain Sanctuary Acopian
Center for Conservation Learning, provided important reference material
regarding Southeast Asia Merops migration. David Melville
and Dr. David Wells read a version of this manuscript and provided
helpful comments. We wish to acknowledge the hospitality shown to
us by members of the tanjung Tuan lighthouse staff.
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