The interactions between long-tailed macaques (Macaca fascicularis) and tourists in Baluran National Park, Indonesia

Abstract

Pre-phd project survey on the abundance of long-tailed macaques in tourist areas in Baluran National Park

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36 © University of Andalas / Copenhagen Zoo
Introduction
The long-tailed macaque (Macaca fascicularis) is
common in many countries in South-East Asia and
classied as “Least concern” on the IUCN Red List
(IUCN, 2015). The population size is declining and in
2008 the long-tailed macaques was the rst species to be
classied as widespread and rapidly declining (Eudey,
2008). Information is needed about the distribution,
population sizes and population trends of the long-
tailed macaque in the wild (Eudey, 2008).
There are many studies concerning the ecology and
occurrence of long-tailed macaques (e.g. Yeager, 1996;
Lucas and Corlett, 1998; de Ruiter and Geen, 1998;
van Schaik et al., 1983), but the past years of drastic
changes and reduction to habitats may have had a
negative impact on distribution and density of the
species. The human encroachment on natural habitats
has caused an increase in human-macaque conicts
(Nekaris et al., 2013; Lane et al., 2011; Fuentes et al.,
2008; Fuentes et al., 2007).
In Baluran National Park, East Java, Indonesia there
is an abundance of long-tailed macaques. According
to park sta, many conicts between tourists and
macaques occur, especially at the most frequently visited
Bekol savannah and Bama beach, where the macaque
population appears to be largest. Park sta suggests
that excessive feeding of the macaques by tourists has
caused the population to increase to “unnatural” sizes
and is concerned that this could result in negative eects
on the ecosystem processes in the area.
There is little information on the occurrence and
behaviour of the long-tailed macaque in Baluran
National Park, and the ecological role and eects of
macaques on the park’s ecosystem processes remains
poorly understood.
This study identies the occurrence of long-tailed
macaques in high tourist density areas of Baluran NP, as
well as investigates the behaviour of macaques in areas
with high visitor density.
Methods
This study took place from 14th-29th July, 2015. Daily
excursions were undertaken in the park between 7am
and 5pm, to identify macaque focus groups and estimate
their population sizes. All observations were carried out
from the main road and tourists trails concurrently by
three observers. We observed the focus groups from
a distance, where our presence did not trigger any
signs of disturbance reaction. “Disturbance reaction”
was dened as a) open mouth threat and yawning
(Angst,1975), b) kra vocalisations by leading males
(Palombit 1992), and c) the push-forward eect, where
groups move away according to distance of researcher
i.e. as researcher approaches, group moves forward
(Williamson and Feistner, 2003). We paused our
approach when the macaques exhibited “disturbance
reaction” behaviour and resumed follows when they
ceased. We used ad libitum sampling (Altmann, 1974)
to record “reactions” and distance as well as physical
anomalies such as missing limbs or snare wounds.
We spent two days searching for groups along the
The interactions between long-tailed macaques (Macaca
fascicularis) and tourists in Baluran National Park,
Indonesia
Malene Friis Hansen1, Hariyawan Agung Wahyudi2, Supriyanto Supriyanto3 and Anida Rahmi
Damanik2
1Roskilde Technical College Vilvorde, Roskilde, Denmark
2Copenhagen Zoo, Indonesia Programme, Copenhagen, Denmark
3Taman Nasional Baluran, Jawa Timur, Indonesia
Corresponding author: Malene Friis Hansen, email: malenefriishansen@outlook.com
Received 27th November, 2015; Revision revision accepted 27th
December, 2015.

37
2015 Journal of Indonesian Natural History Vol 3 No 2
main access road at the western part of the park. The
locations of the encounters were recorded using GPS
(Garmin Cs62), and all groups were named according
to the location where they were encountered. The
population size of each recorded group was estimated
with repeated total counts (Roos and Reeve, 2003) along
with ad libitum observations. No discrimination to age/
sex class was given and individuals were not identied.
All outermost locations, where groups were encountered
or footprints recorded, were used to estimate a groups’
approximate home range.
Human-macaque interactions were observed at Bekol
savannah and Bama beach for 1hr/day for four days
within one week. We used continuous all-occurrence
sampling (Altmann, 1974) with two behaviours; tourist
feeding macaque and macaque showing aggression
towards tourists. “Aggression” was dened as contact
aggression and open mouth threat. We also used
ad libitum sampling for the observation of tourists-
macaque interactions (Altmann, 1974). Concurrently,
we estimated the number of tourists and macaques
present at any given study time with no age/sex class
discrimination, and calculated the correlation coecient
(r) of the samples.
Results
Group size and home-ranges
We identied nine groups and estimated the group
sizes (averages of repeated counts), home ranges and
densities (Table 1). We counted 859 individuals in
the nine groups (Table 1). The four highlighted focus
groups were encountered in high-tourist-density areas.
The “Kantor” group was observed both on the main
road and along the public road. Groups 6-9 were only
encountered along the main road. Of the focus groups
“Bekol-2” had the smallest estimated home-range
(1km2), and “Bekol-1” the largest density with 90
individuals per km2 (Table 1). The 417 individuals in
the four focal groups utilised an estimated home range
averaging 1.75km2/group (Fig.1), with an average
density of 59 individuals/km2/group and a maximum
group size of 180 individuals (Table 1). The average
group size consisted of 104 individuals/group.
Close follows of the macaques without provoking any
reactions from the study group were possible in the main
tourist areas only --- that is, Bama and Bekol. Outside
these areas, an immediate “push-forward eect” took
place and groups moved away when we approached and
maintained a distance of 20-30m. Leading males and
mature females exhibited disturbance reactions, such
as kra vocalisations and contact calls (Palombit, 1992),
yawning, and “open mouth” threat.
We recorded several types of physical anomalies, such
as missing tails and limb(s), and three individuals were
observed with a metal snare around their stomach that
had caused deep esh wounds.
The three groups Bekol-1, Bama and Manting have
Group name nHR (km2) Density
Kantor 100*
Bekol 1 180 2 90
Bekol 2 53 1 53
Bama 84 2 42
Manng 100 2 50
Waduk 1 70
Waduk 2 66
Curah tangis 106
Bitakol 100*
Total 859
*Approximate number
Table 1. Macaque group sizes (n), approximate home ranges
size (HR), densies (n/km2) and focal groups (bold).
Figure 1. Home-ranges of Bekol-1, Bekol-2, Bama and
Manng groups.
Interactions between long-tailed macaques and tourists

38 © University of Andalas / Copenhagen Zoo
similar home-range sizes that seem to overlap only
minutely (Fig. 1). Bekol-2 has the smallest home range
and group size, and this group has less encounters with
tourists. Manting was most frequently observed in the
mangrove along a birding trail, and only two times near
the main road.
Human-macaque interactions
Our occurrence sampling revealed a strong positive
correlation between the number of tourists and frequency
of tourist feeds (r = 0.825; Fig.2), whereas the number
of monkeys present was strongly negatively correlated
to the number of humans present (r = -0.916; Fig.3).
There was a moderate negative correlation between the
number of tourists and aggressive macaques (r = -0.63;
Fig.3). Ad libitum observations conducted for a longer
period of time support these trends i.e. macaques tended
to shy away from large human crowds. Bama group
members retracted to the forest areas behind the berm
and the mangrove, and the Bekol group dispersed into
smaller units away from Bekol savannah.
Tourists fed macaques mostly rice and potato chips. On
the 20th July, the number of feeding reached an average
of 80/hour. During times with low visitor numbers,
macaques frequently scavenged on human trash in bins
and on the ground.
Discussion
This study revealed that tourist feeding of long-
tailed macaques in Baluran NP is excessive and
that it may impact the macaque population density
by creating sustenance for extremely large groups.
Our results suggest elevated population densities in
tourist areas. Some groups had population sizes over
100 individuals, and one reached 180 individuals.
This corresponds well with study groups in Vietnam,
where provisioned reached populations sizes of 180
individuals and densities at 62 individuals/km2 (Son,
2004). In comparison, non-provisioned study groups in
Sumatra averaged 30 individuals, with few exceeding
40 individuals (van Schaik et al., 1983). Since primate
group sizes are inuenced by food density (Wrangham
et al., 1993), groups in excess of 100 individuals are
unlikely to occur. Groups exceeding 40 individuals
already exhibit increase in day journey length, foraging
time and experience an elevated level of social tension
(van Schaik et al., 1983). Human provisioning is not the
Figure 2. Amount of tourist feeds in Bekol and Bama for 1
hour/day for 4 days.
Figure 4. Amount of aggressive macaque behaviours directed
towards tourists in Bekol and Bama for 1 hour/day for 4 days
Figure 3. Monkeys present in Bekol and Bama for 1 hour/day
for 4 days
Hansen et al.

39
2015 Journal of Indonesian Natural History Vol 3 No 2
only possible reason for the large dierence in group size
and population density between Baluran and Sumatra.
The dierence in habitat type and the level of predator
pressure may also determine group sizes (Cowlishaw
and Dunbar, 2000). In a situation without human
provisioning, it is expected that macaque group sizes
in Baluran were signicant larger than Sumatran group
sizes, due to more favourable ecological conditions.
Using disturbance reactions as our guiding tool
proved adequate, and we were able to observe groups
foraging and interacting if we remained 20-30ms away.
We recommend a habituation period before conducting
further studies if more subtle behaviours and individual
identication is sought.
The positive correlation between the number of tourists
and the number of feeds (r = 0.825; Fig.2) suggest that,
on days with many tourists, the volume of extra feed
available to macaques is sucient to modify the group
sizes positively. These enlarged groups, however, may
not be able to sustain themselves from natural food
sources alone and, therefore, become reliant on surplus
food oered by tourists. This means they will seek
tourists areas, where more energetically cost-eective
tourists food is plenty, rather than foraging on natural
food sources. Despite being attracted to tourist food,
the large Bama and Bekol groups avoided tourists on
days with high visitor numbers (r = -0,916) (Fig.3) and,
naturally, with fewer macaque-human interactions, the
amount of aggression also decreased (r = -0.63; Fig. 4).
The negative correlation between the number of humans
and macaques aggression, however, seems counter-
intuitive, and the reason for macaques retreating at high
visitor numbers is not clear. It may be linked to the
availability of excessive amounts of food that, in turn,
reduces competition and allows the macaques to rapidly
feed until full and retreat. It could also be related to an
evolutionary inherent group vigilance that initiate retreat
at a pre-determined point, irrespective of the potential
benets from scavenging human food outweigh the
risks. Finally, social behaviour may determine retreat
i.e. a group will follow certain dominant leaders and
leave when these are full, irrespective of whether the
subordinates themselves are full or not. In times with
many visitors, it is likely that dominant individuals
are the rst to feed and become full. This may also
explain why a retreated group has individuals that rests
and others that continue to forage. Relying on tourists
food, however, may impair macaque health and group
welfare. An elevated daily intake of carbohydrates and
other anthropogenic foods often results in increased
adipose deposition and reduced activity rates (Zhao,
2005). In addition, larger macaque group sizes will have
less group resting time than smaller group sizes (van
Schaik et al., 1983), and increase inter-group conicts
and competition (Zhao, 2005).
Macaque aggressive behaviour towards humans
decreased with an increase in number of tourists (r =
-0.63; Fig. 4). This is likely due to the amount of tourist
food is so large that all individual macaques can feast
without having to compete for it. With only few tourists
present, many macaques resort to actively stealing or
grabbing food out of tourists’ bags, cars and pockets.
This type of aggressive “begging” occurred primarily
on days with few tourist visits and less tourist food
available. Similar aggressive behaviour has been
reported in Padangtegal and Sangeh Monkey Forest
temple on Bali, where tourist reports of biting, hitting
and scratching macaques are common. Aggressive
behaviour was also recorded on days with high visitor
numbers, however, instigated by tourists actively
pursuing macaques to oer them food, even when these
did not want it.
Close interactions between humans and macaques
can increase the risk of injuries and transmission of
zoonotic diseases (Jones-Engel, 2005; Fuentes et al.,
2007; Zhao, 2005) lethal to humans, for example, the
Herpes-virus B. People infected with this virus sustain
a mortality rate of 70% (Engel et el., 2002), and the
prime instigator of human-macaque interactions leading
to such inter-species disease transmissions is food
(Fuentes et al., 2008). Pathogen transmission can also
occur via macaques rummaging through human trash
(Fuentes et al., 2008). On the other hand, macaques
living in urban or rural centres as integrated components
of human societies risk suering serious injuries from
snares, broken glass, cans and plastic bags. This study
recorded several individuals with missing limbs and
embedded strings. Many of these likely arise from
illegally deployed snares and poor waste management
in the park.
Long-tailed macaques are known to disperse seeds
and play important roles in forest regeneration in a
variety of habitats (Lucas and Corlett, 1998). Excessive
feeding of macaques may encourage them to rely on
easily obtainable tourist food, thereby reducing their
seed dispersal activities and, consequently, cause
habitat deterioration.
Interactions between long-tailed macaques and tourists

40 © University of Andalas / Copenhagen Zoo
Our study concludes that macaques group sizes in
Baluran NP are inated due to excessive tourist feeding.
This leads to a potentially more serious problem i.e.
aggressive human-macaque interactions. In contrast
to the anecdotal evidence, suggesting macaques
solicited interactions, we observed that it was primarily
visitors that solicited the macaques. To reduce the
risks of injury and disease transmissions, the human-
macaque interactions need to be reduced. In Singapore,
for example, physical contact between humans and
macaques is rare and disease transmission risk low,
because it is illegal to feed macaques and the laws are
rigorously enforced. In addition, visitors and locals alike
are educated about the possible negative consequences
of close physical interactions with macaques (Fuentes
et al., 2008).
The current situation in Baluran NP necessitates
an immediate management intervention aimed at
reducing the feeding of macaques. The existing laws
concerning feeding the macaques need to be enforced,
and education and awareness programmes for visitors
implemented. This combination of activities can reduce
contact between macaques and humans and reduce the
disease transmission risk in Baluran NP.
Acknowledgements
We would like to thank the management and sta
of Baluran National Park: Kepala Balai Ibu Emi
Endah Suwarni and Kepala Sub Bagian Tata Usaha
Pak Joko Waluyo for the permission and support to
conduct this study, and for all their help. Thank you
also to Copenhagen Zoo, especially Diki Kasandra,
Carl Traeholt, Pak Indra Arinal and Bengt Holst for
supporting this study both nancially, with sta, and
with ideas.
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