Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 May 2022 | 14(5): 20964–20969
ISSN 0974-7907
(Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.7758.14.5.20964-20969
#7758 | Received 22
November 2021 | Final received 21 February 2022 | Finally accepted 09 May 2022
Cases of fatal electrocution of
the endangered Javan Gibbons (Mammalia: Primates: Hylobatidae)
by power lines
Yoonjung Yi 1, Soojung Ham 2, Rahayu Oktaviani 3, Mia Clarissa Dewi
4, Muhammad Nur 5,
Ani Mardiastuti
6 & Jae. C. Choe 7
1 Laboratory of Animal Behaviour
and Conservation, College of Biology and the Environment, Nanjing Forestry
University, No.159 Longpan Road, Nanjing, 210037,
Jiangsu China.
1,2,7 Division of EcoScience,
Ewha Womans University, 52,
Ewhayeodae-gil, Seodaemun-gu,
Seoul, 03760, Republic of Korea.
3,5 Javan Gibbon Research and
Conservation Project, Kampung Citalahab Sentral, Desa Malasari,
Kecamatan Nanggung, Bogor, Jawa Barat 16650, Indonesia.
3 Yayasan Konservasi
Ekosistem Alam Nusantara
(KIARA), Komplek Laladon Indah, Jl. Kamojang
C4/15, Laladon, Ciomas,
Bogor, Jawa Barat 16610, Indonesia.
4 Universitas Yuppentek
Indonesia, Jl. Perintis Kemerdekaan I No.1,
RT.007/RW.003, Babakan, Kec.
Tangerang, Kota Tangerang, Banten 15118, Indonesia.
6 Department of Forest Resources
Conservation and Ecotourism, Faculty of Forestry and Environment, IPB
University, Jl. Raya Dramaga, Babakan,
Kec. Dramaga, Kota Bogor, Jawa Barat 16680, Indonesia.
1 yi.yoonjung@gmail.com
(corresponding author), 2 soojungham@gmail.com, 3 rahayu_oktaviani@yahoo.com,
4 miaclarissa@gmail.com,
5 nuy011088@gmail.com, 6 aniipb@indo.net.id,
7 jaechoe9@gmail.com
Editor: H.N. Kumara,
Sálim Ali Centre for Ornithology and Natural History,
Coimbatore, India. Date of publication: 26 May 2022
(online & print)
Citation: Yi, Y., S. Ham, R. Oktaviani, M.C. Dewi, M. Nur, A. Mardiastuti & J.C. Choe (2022). Cases of fatal electrocution of
the endangered Javan Gibbons (Mammalia: Primates: Hylobatidae)
by power lines. Journal of Threatened Taxa 14(5): 20964–20969. https://doi.org/10.11609/jott.7758.14.5.20964-20969
Copyright: © Yi et al. 2022. Creative Commons Attribution
4.0 International License. JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: The present research has been supported by the
National Research Foundation of Korea (NRF) funded by the Ministry
of Education (2021R1A6A3A03039709) to YY and Amore
Pacific Academic and Cultural Foundation (AACF). YY is supported
by the Foreign
Youth Talent Program (QN2021014010L) from the Ministry
of Science and Technology and Research Grants (2021K310C) from
Department of Human Resources and
Social Security of Jiangsu Province of the People’s Republic of China.
Competing interests: The authors
declare no competing interests.
Author details: Yoonjung Yi is a post-doctoral researcher working on behavioral ecology
and sociobiology of primates and other wildlife, mainly focusing on inter-group
encounters, parental care, and pair-bond.
Soojung Ham is a Ph.D. scholar specializing in
the singing behaviors of Javan gibbons and currently working for animal rights and
welfare. Rahayu Oktaviani is a primate
conservationist and a co-founder of the non-profit organization KIARA to
protect Javan gibbons and conduct community engagement programs. Mia
Clarissa Dewi is a lecturer and head of
quality assurance in college, primarily working on conservation, environmental
economics, and ethnozoological research.
Muhammad Nur is a field
coordinator in the Javan Gibbon Research and Conservation Project while
contributing to field research and conservation education. Ani Mardiastuti is a professor who has been working on
biodiversity, wildlife conservation, wildlife trade & law enforcement in
Indonesia, mainly focusing on avians. Jae C. Choe is a chair professor who has been working on
evolutionary biology, such as sexual selection and social evolution in insects,
behavior and ecology of birds, primates, and cetaceans.
Author contributions: YY,
SH, RO, MCD, MN collected data in the field; YY wrote the manuscript; SH, RO,
AM, JCC revised the manuscript.
Acknowledgements: This project was conducted in
collaboration with the IPB University and Ewha Womans University. We thank the Indonesian Ministry of
Research and Technology (RISTEK), the Indonesian Ministry of Environment and
Forestry (KLHK), and the Gunung Halimun-Salak
National Park (GHSNP) for the research permissions. We thank Amael Borzee for helpful comments
on the manuscript.
Abstract: Human-made structures are often
deadly to wildlife. Power lines from electric poles can cause serious injury
and even death of wildlife via electrocution, especially of arboreal primate
species that can easily access power lines. Here, we reported three cases of
wild ‘Endangered’ Javan Gibbons Hylobates moloch electrocuted by power lines along a road between
a tea plantation and a village adjacent to Gunung Halimun-Salak National Park area, West Java, Indonesia. In
all cases, the adult male Javan Gibbons jumped and grabbed a power line hanging
at the edge of the forests and immediately died. Our case reports highlight
that power lines can have a critically adverse effect on the survival of wild
animals, particularly on highly arboreal species such as Javan Gibbons. We
argue the need for mitigation plans (e.g., cable insulation) for power lines in
areas at risk. Such areas should be determined based on wildlife habitat
monitoring and the study of ranging behaviors,
focusing on areas with high risks of electrocution.
Keywords: Anthropogenic mortality,
arboreal primates, human-made structures, Hylobates
moloch, power lines.
Introduction
Human-made
structures often disconnect and fragment the habitat of wildlife animals,
negatively impacting their survival and potentially leading species to local
extirpation (Rudolphi et al. 2014; Warner et al.
2021). Electric poles, a power line element, are one of the human-made
facilities that can be deadly to various animal species. A power line can cause
immediate death by electrocution or serious injuries when touched
simultaneously with another non-electric current object or a wire with a
different voltage (Kumar & Kumar 2015; Schulze et al. 2016). Although bird
electrocutions are well documented and studied (Loss et al. 2014; Pérez-García
et al. 2017), arboreal mammal species such as primates are also especially
vulnerable given their high accessibility to the power lines (Moore et al.
2014; Kumar & Kumar 2015; Katsis et al. 2018).
Considering
electrocutions of primates, several long-term studies reported that 32 to 40%
of them eventually died after an electric shock from a power line (Macaca mulatta:
Kumar & Kumar 2015; Alouatta guariba clamitans: Lokschin et al. 2007; Semnopithecus
vetulus vetulus: Roscoe
et al. 2013). The most extended study from 1998 to 2019 in Kenya found 73% of
the death is due to electrocution in four monkey species (Cunneyworth
& Slade 2021). In addition, electrocution was the reason for 36% of deaths
observed in Hanuman langurs in Jodhpur, India (Semnopothecus
entellus entellus; Ram et al. 2015) and 16% of
four primate species in Kenya (Colobus angolensis
palliates, Cercopithecus mitis albogularis,
Chlorocebus pygerythrus
hilgerti, & Papio
cynocephalus cynocephalus: Cunneyworth et al. 2021). These results suggest that
electrocution contributes highly to mortality in primates, especially in urban
areas where humans and wildlife co-exist.
Java is the
most heavily populated island of Indonesia with more than 140 million people
while also hosting various wildlife habitats. Due to the continued
deforestation in Java, less than 10% of forests remain, and the remnant is also
heavily fragmented (Nijman 2004, 2013). Gunung Halimun-Salak National Park (GHSNP) has the largest
remaining forest blocks in Java and it is the host to high biodiversity
(MacKinnon & MacKinnon 1986). These areas can provide ecological services
not only to wildlife but also to humans. However, throughout the year, with the
increasing growth rate of the human population, infrastructure like roads and
power lines are traversing areas close to the conservation area and could cause
negative effect on wildlife.
The Javan
Gibbon Hylobates moloch
is an ‘Endangered’ primate and the main threats are deforestation and hunting
for pet trade (Nijman 2020). While around 4,000 Javan Gibbons are left in the
wild, GHSNP holds between 900 and 1,221, the largest remaining wild population
(Nijman 2004; Supriatna 2006). Similar to other
gibbon species, Javan Gibbons are highly arboreal, spending most of their time
in the canopies (Cheyne 2011). As a result of their movement through
brachiation, gibbons are at high risk of electrocution when electric poles are
installed in their habitats. Several electrocution of gibbons have been
reported in the media (The Wildlife Trade Monitoring Group 2020; The Straits
Times 2019; Zon Pann Pwint 2019), but rarely in the scientific literature
(Talukdar et al. 2018). In this study, we report and describe three cases of
electrocuted wild Javan Gibbons in 2011, 2015, and 2021 at the edge of the
forest close to GHSNP.
Methods
Study site
The Javan
Gibbon is one of the three key species of GHSNP, along with Javan Leopards Panthera pardus melas and Javan Hawks Nisaetus
bartelsi. In addition to Javan Gibbons, the
endemic Javan Lutung Trachypithecus
mauritius and the endangered Javan Surili Presbytis comata are also found in the National Park. While GHSNP
supports one of the largest Javan Gibbon populations, their habitats are still
fragmented due to deforestation and human facilities (Smith et al. 2017). The
field site in Citalahab is also located on the edge
of primary forests and is surrounded by tea plantations and rice paddies (Yi et
al. 2020).
Study
subject
The Javan
Gibbon Research & Conservation Project (JGRCP) began in 2007 in Citalahab area in GHSNP (-6.739167 S, 106.530000 E), with a
focus on behavior and ecology of wild Javan Gibbons
(Kim et al. 2012; Ham et al. 2017; Oktaviani et al.
2018; Yi et al. 2020; Jang et al. 2021). The home ranges of the gibbon groups
that are regularly followed by the research team are located along the tea
plantation, separated by a one-lane dirt road. We expect a similar habitat
shared with human facilities for other gibbon groups in GHSNP. Given the
long-term research going on in the area, local people are aware of Javan
Gibbons and therefore direct threats towards the gibbons are relatively low
compared to other habitats.
Data
collection
The
observations of electrocuted Javan Gibbons were opportunistic, temporarily
matching within the frame of the long-term research project. We collected the
date, location and context of the electrocution events.
Results
We observed
three cases of electrocution of Javan Gibbons on power lines over the 15 years
of long-term research along the road and the tea plantation adjacent to GHSNP
(Image 1).
Case 1
22 February
2011: We found a dead gibbon holding a power line at Malani
area (-6.710944, 106.512500). The individual had died a few days prior (pers.
com. Cikaniki Research Station) and it was collected
before 25 February 2011. The GHSNP staff witnessed the electrocution at the
edge between forest and tea plantation. The gibbon jumped and held on to the
power line unexpectedly because of a falling tree behind and was electrocuted.
The dead gibbon was stuck to the power line until the GHSNP staff requested the
national electricity company to turn the power off a few days later (Image 2).
There was not much flesh left on the body and its head was missing after
falling to the ground probably due to the electrocution and decomposition.
Because of the bad condition, the GHSNP staff buried the gibbon body directly
and we could not obtain further information. We suspect the dead gibbon was an
adult male from the body size.
Case 2
23 March
2015: A local resident found an electrocuted gibbon close to Malani area (-6.727778, 106.493889), and suspected that
human disturbance made the gibbon to jump onto the power line. The electrocuted
gibbon’s face and left arm which held the power line were damaged. No other
gibbons were observed around at the time of electrocution. For necropsy, the
body was delivered to LIPI (Indonesian Institute of Sciences) in Bogor. The
individual was an adult male, with a body length of 530 mm and a weight of 5.5
kg (Image 3). Later, the specimen was deposited at the GHSNP headquarter in Kabandungan area as education material.
Case 3
13 December
2021: A local resident found an electrocuted gibbon close to Ciwalen (-6.705809, 106.521170). The right side, especially
the arm and flank, of the dead gibbon were seriously damaged probably when
touching the power lines. The residents buried the dead body close to the road.
From the pictures taken by the resident, we assume the dead gibbon was an adult
male.
Power line
installed in the region
The voltage
running through the power line is above 20 kv for
main, 20 kv for medium, 220 v for low voltage. The
number of wires is: three phases and three wires for medium, three phases and
four wires for low voltage. All cables are horizontally arranged. Therefore,
the gibbons likely held medium voltage (20 kv)
cables. There is an insulator in the medium cable, however, the insulation
strength is only up to 6 kv, and holding it for more
than a few seconds will break the insulator and lead to death.
Discussion
In this
study, we described three cases of electrocution of Endangered Javan Gibbons on
electric power lines along with their natural habitat. These observations
highlight the effect of power lines on highly arboreal species such as Javan
Gibbons. Given that these data are obtained opportunistically, there may be
more actual number of electrocution cases in more remote and uninhabited areas.
At the study site, some of the power lines pass along the road and inside
forest patches. As a result, its presence can be a great threat to the wildlife
in the forest, mainly for birds and arboreal mammals. Thus, we suspect similar
but unreported cases of Javan Gibbon, or other wildlife injury or death, caused
by electrocution in the study area.
While
arboreal species have relatively low chances to be hit by vehicles (roadkill),
power lines are easily reachable for them. Among primates in general, mortality
resulting from electrocution seems to be higher in arboreal than in terrestrial
species (Al-Razi et al. 2019; Cunneyworth
& Slade 2021). While previous reports on primate electrocution are mostly
from urban areas (Printes 1999; Goulart et al. 2010; Corrêa et al. 2018; Pereira et al. 2020), our cases
indicate that power lines can cause fatality in forested areas as well.
Moreover, along with the cases reported in this study, three more electrocuted
gibbons were found outside the protected areas in the last four years: two
cases from Gunung Gelap Garut, Cisewu between January and
February 2022 (-7.370986, 107.497615; pers. com. Sigit
Ibrahim, The Aspinall Foundation, Indonesia) and one case in 2018 from Lengkong, South Sukabumi
(-7.127500, 106.687222). This suggests that the endangered Javan Gibbons
suffers from power line mediated electrocution both in urban and forested
areas.
People
living in the study site were previously isolated because there was no
electricity and mobile signal before electric poles were set up in 2011–2012.
Despite the benefits of offering electricity to the local community, the cases
reported in the study highlight that the increase in human facilities,
especially in the areas surrounding protected areas, has negative effects on
wildlife. A recent study of population viability analysis revealed that Javan
Gibbons might go extinct within the next 100 years if existing threats such as
hunting and deforestation remain the same (Smith et al. 2017). Electrocution
caused by power lines may hasten this trend. Therefore, mapping the priority
areas to apply mitigation measures will be an urgent step to decrease the threats.
Furthermore, a typical conservation approach to preserve Javan Gibbon
populations, the distribution of power lines should be considered a relevant
determinant of possible mortality risk.
With the
cases reported in our study, we conclude that the installation of human
infrastructures such as electric poles needs to take into account conservation
management practices. First, power line installations should practically avoid
the habitats of Javan Gibbons according to the mitigation hierarchy, and should
follow the application of wildlife standards (Kiesecker
et al. 2010). Then, mitigation efforts such as insulation or burial of electric
cables, artificial canopy bridges will help lower the mortality of the species
(Janss & Ferrer 1999; Katsis
et al. 2018). In Sri Lanka, the electrocution cases of the Toque Macaques Macaca sinica
significantly dropped from 18 to zero after the installation of shields on
electric poles (Dittus 2020). Given the cost of
mitigation efforts, it is critically important to understand habitat use and
the ranging behaviors of species as well as to
investigate and prioritize mitigation in high-risk areas, for instance where
power lines pass along the forests. For example, mitigating actions are
spatially prioritized based on the systematical
analyses of spatial occurrence of electrocution in five primate species between
1998 and 2016 (Katsis et al. 2015). Wildlife Javan
Gibbon electrocution mortality in areas close to GHSNP must be promptly and
appropriately addressed through monitoring and conservation management
practices.
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