Journal of Threatened Taxa | www.threatenedtaxa.org | 26
December 2019 | 11(15): 14927–14941
Observations
on the ex situ management of the Sumatran Rhinoceros Dicerorhinus
sumatrensis (Mammalia: Perissodactyla:
Rhinocerotidae):
present
status and desiderata for conservation
Francesco Nardelli
IUCN/SSC Asian Rhino Specialist Group; Save the Rhino
International
(personal address) 5 Via Torricelli - 00042 Anzio -
Italy.
franardelli@gmail.com
Abstract: The Sumatran Rhinoceros is approaching extinction. A few dozen animals remain, dispersed in
dwindling Indonesian rainforest with only a few years of likely survival
time. Eight
rhinos belonging to two subspecies are in controlled breeding
centres. The Sumatran Rhinoceros differs
markedly from the other four species of Rhinocerotidae
and requires management according to specific protocols. Several Sumatran Rhinoceros have died in
zoos, owing to lack of knowledge concerning their particular dietary
requirements and their high sensitivity to anthropogenic activities. Recently more positive results, including
successful births, have been achieved with the aid of scientific research,
which continues to examine factors required for successful conservation and
accommodation efforts.
Keywords: Asiatic Two-horned Rhinoceros, behaviour,
captivity, endangered species, ecology, forest protection, nutrition.
Abstrak: Badak Sumatera menuju kepunahan. Hanya beberapa lusin saja tersisa,
tersebar di hutan hujan Indonesia
yang semakin menipis dengan tinggal beberapa tahun waktu bertahan hidup. Delapan badak, satu milik
subspesies, berada di pusat penangkaran
terkendali. Badak Sumatera berbeda dari empat spesies
lain dari Rhinocerotidae dan membutuhkan pengelolaan menurut protokol khusus. Beberapa Badak Sumatera mati di kebun
binatang, karena kurangnya pengetahuan tentang persyaratan diet khusus dan
sensitivitas mereka yang tinggi terhadap aktivitas antropogenik. Baru-baru
ini hasil yang lebih positif, termasuk kelahiran yang berhasil, dicapai dengan bantuan penelitian ilmiah, yang terus memeriksa faktor-faktor yang diperlukan untuk upaya konservasi
dan akomodasi yang berhasil.
doi: https://doi.org/10.11609/jott.4952.11.15.14927-14941
Editor: Karin
Schwartz, Conservation Planning Specialist Group (CPSG), Apple Valley, USA. Date of
publication: 26 December 2019 (online & print)
Manuscript details: #4952 | Received 15 March 2019 | Final received 04
November 2019 | Finally accepted 27 November 2019
Citation:
Nardelli, F. (2019). Observations on the ex situ management of the Sumatran
Rhinoceros Dicerorhinus sumatrensis
(Mammalia: Perissodactyla: Rhinocerotidae):
present status and desiderata for conservation. Journal of Threatened Taxa 11(15): 14927–14941. https://doi.org/10.11609/jott.4952.11.15.14927-14941
Copyright: © Nardelli 2019. Creative Commons Attribution 4.0 International
License. JoTT
allows unrestricted use, reproduction, and distribution of this article in any
medium by adequate credit to the author(s) and the source of publication.
Funding: None.
Competing interests: The author declares
no competing interests. The
views expressed are those of the author.
Author details: 1976–1982 Owner of Rare Felids Breeding Center, Italy.
1982–1985 Curator of Howletts & Port Lympne Wildlife Parks, UK. 1985–1993 Director of Save the
Sumatran Rhino Project, Indonesia. Author of “The Rhinoceros a Monograph”,
1988. A table book printed in a limited edition by Basilisk Press, London
besides a number of papers on Asian Rhinos and ex situ conservation planning
and management. Presently, indipendent wildlife
conservationist. Member of the IUCN/SSC Asian Rhinos Specialist Group and a
Patron of Save the Rhino International.
Acknowledgements: Special thanks and appreciation go to Karin Schwartz
for editing this paper. I wish to thank
my copyeditor in Kenya and the anonymous peer reviewers for their most valuable
comments. Comprehensive writing on
rhinos is possible from the thousands of papers available at the remarkable
Rhino Resource Centre. Besides gratitude
for the people concerned, we ought to consider supporting the RRC as well as
rhino conservation organizations that create awareness about the tragic
destruction of rhino populations and their efforts to avoid extinction,
incessantly motivated by the absurd request by some members of our species to
obtain rhino horn.
Introduction
The emergence of the Asiatic Two-horned Rhinoceros,
popularly known as the Sumatran Rhinoceros Dicerorhinus
sumatrensis (Fischer 1814), has been dated to the
lower Miocene between 23 and 16 million years ago (Tougard
et al. 2001). The species has shown
little morphological change since then, leading some to refer to Sumatran
Rhinos as “living fossils” (Groves 2017).
Historically these rhinos have a large distribution area that once
included northeastern India, Bangladesh, Myanmar,
Thailand, southern China, Indochina, Malaysia, and Indonesia. Currently, only about 50 Sumatran Rhinos
remain in small populations scattered in refuges in Sumatra and in Borneo.
Three subspecies have been described: the Sumatran or
Southern Asiatic Two-horned Rhinoceros Dicerorhinus
sumatrensis sumatrensis (Fischer,
1814) (Image 1). The range of this
subspecies once extended from the southernmost parts of Myanmar and Thailand (Kra Isthmus) through peninsular Malaysia to the Indonesian
island of Sumatra. Very small
dispersed populations are still present in Sumatra. The Northern Asiatic Two-horned Rhinoceros Dicerorhinus sumatrensis
lasiotis (Buckland, 1872) (Image 2), which is
likely extinct, once ranged from the northeastern
part of the Indian subcontinent to northern Myanmar and parts of Indochina;
reports of occurrence from as far east as Sichuan are dated during the Song
Dynasty (960–1279) (Rookmaaker 1980). The Bornean Two-horned Rhinoceros Dicerorhinus sumatrensis harrissoni (Groves, 1965) (Image 3) was historically
present in much of Borneo; a few individuals survive in a small area in the
heart of the island.
Sumatran Rhinos are by far the smallest of the five
living species of rhino. On average,
they weigh 600–950 kg, stand 1.0–1.5 m tall at the shoulder, and are about
2.0–3.0 m long (IRF 2019). The head is
70–80 cm long and the tail varies in length from 35 to 60 cm. This species has two horns, dark grey to
black in colour, which in the wild are usually very smooth and form a slender
cone that is curved backwards. A typical
front horn of the Sumatran Rhinoceros is 15–25 cm long, although there is a
horn 80cm long in the British Museum collection. The smaller second (posterior) horn is
normally much smaller, seldom more than a few cm in length, and it is often not
more than an irregular knob. D. sumatrensis has distinctive reddish-brown skin, which
in the wild is variably covered with short bristly hair. In captivity the hair can grow out to a
shaggy fur owing to less abrasion from vegetation. The ear edges have a prominent fringe of
longer hairs, and the tail terminates with a tuft of thicker hairs. Two prominent folds in the skin circle the
body behind the front legs and before the hind legs, and lesser folds occur on
the neck and at the base of the legs.
The Sumatran Rhino is a solitary folivore of the southeastern Asian lowland and mountain (i.e., moss)
rainforests. It is an induced ovulator, with females ovulating in response to external
stimuli during or before mating rather than ovulating cyclically or
spontaneously. This is the first example
reported within the Perissodactyla (Roth et al.
2001). The gestation period lasts 16
months and females produce a single calf every 3–4 years. The typical low density of rhino populations
is likely attributable to their dietary specialization for eating specific leaves
that tend to be highly localized.
Consequently, Sumatran Rhinos
require large, undivided and undisturbed areas, which have all but vanished
(Cannon et al. 2009). Dicerorhinus sumatrensis
is listed as Critically Endangered by the IUCN Red List (van Strien et al. 2008).
The biggest threats to Sumatran Rhinos are poaching for their horn,
inbreeding depression, and loss of habitat due to anthropogenic
development. The horn is used in Asia as
a medicine against fever and pain, and trade in rhino horn between Borneo and
other source areas in southeastern Asia and China
likely began more than 2,000 years ago with the origin of traditional Chinese
medicine. Use of rhino horn has recently
reached a plateau as a “status symbol” among the rich populations of China,
Viet Nam (Milliken 2012) and Thailand (pers. info.).
Over the centuries, the Sumatran Rhinoceros has been
exterminated over most of its range. In
2003 fewer than 300 Sumatran Rhinos were living in the wild. Most of these were in Bukit Barisan Selatan, Gunung Leuser and Way Kambas National
Parks Sumatra, Indonesia, although a few were found in Borneo. By 2019 the situation had deteriorated
considerably with no more than 80 rhinos left, for the most part in Gunung Leuser National Park (IRF
2019).
Background
Sumatran Rhinos are rarely seen in the wild,
confounding efforts to study them by direct observation (van Strien 1985) and limiting knowledge concerning their
numbers, ecological aspects and management in controlled environments. In 1985
van Strien (1985) estimated that as many as 800
Sumatran Rhinos remained, while less than 30 years later, Nardelli (2014)
estimated about 75 were still alive.
Recently, some experts have estimated that as few as 30 animals survive
(Hance 2017).
From this apparent rate of decline, it would appear that the last wild
populations of Sumatran Rhinos will soon be gone. This may be viewed as a total conservation
failure. While all rhino habitats are
strictly protected by legislation, in reality many areas are subject to
large-scale human encroachment that the national park management has neither
the means nor political support to prevent.
Thus establishment of Sumatran Rhino populations in well managed
conservation areas will be a vital component of future conservation strategy.
One of the conclusions reached at the Sumatran
Rhinoceros Crisis Summit in Singapore (31 March–04 April 2013) (Lees 2013) was
that ex situ facilities holding Sumatran Rhinos ought to participate in the
following essential tasks: 1) form “insurance” populations to re-establish or
genetically invigorate wild populations, granted that strong protection
measures are in force; 2) undertake research to improve knowledge of rhino
biology; 3) promote the Sumatran Rhino as a “flagship species” to draw
attention to the biodiversity spots they inhabit and educate the local
communities on the importance of conservation.
Nevertheless, and despite problems in captivity such as high mortality
and poor gestation mostly resolved (Roth 2003), these resolutions are redundant
topics for discussions pro and contra diverging conservation strategies (Hance 2018a,b).
The existing ex situ population of the Sumatran
Rhinoceros is not viable (Lees 2013; Putnam 2013). Hazardous inertia has left the tiny group
concentrated at the Sumatran Rhino Sanctuary (SRS) on Sumatra Island in
Indonesia on its own to sustain the survival of the species, perhaps for no
more than a few decades, unless more rhinos are captured without delay and
moved into controlled areas. Scientific
research has proved useful at solving technical “how to” problems but not at
working out precise “whether to” efforts.
We cannot expect science to do any more than feed data into ethical or
political decisions, which are lacking.
Unfortunately, conservation is not only scientific, it
is multi-faceted and, according to anthropomorphic standards, aesthetically
biased (e.g., “beautiful” tiger vs. “ugly” rhinoceros) even, requiring social
science aspects as well as biological sciences to lead towards the proper solutions.
In April 2016, an attempt to capture a female rhino in
Kalimantan, the Indonesian region of Borneo, ended with its loss (Meijaard 2016). In
2018 a decision was finally taken to capture isolated Sumatran Rhinos and
scrupulous conservationists started to reunite those “lost-in-the-woods” rhinos
(IRF 2018a); on 25 November 2018 a female Sumatran Rhinoceros, Pahu, was safely captured.
On the same day and month in 1985, the male Torgamba
was the first to be rescued by Save the Sumatran Rhino, a project of the
Indonesian Directorate General of Forest Protection and Nature Conservation
(PHPA) and the UK’s Howletts & Port Lympne Wildlife Parks (H&PL) (King 2013; King and Beer
2018). Between 1985 and 1994, 16 rhinos
from Sumatra followed Torgamba’s safe arrival at
H&PL, in the care of zoological institutions in Indonesia (Jakarta, Bogor,
and Surabaya zoos), the UK (H&PL) and the USA (Cincinnati, Los Angeles, New
York, and San Diego zoos, which had joined the project). Let us hope this coincidence of dates is a
good sign that the ongoing capture and translocation will be as successful as
the precedents.
Overview of the current
status of the Sumatran Rhinoceros in a controlled environment
The situation at Borneo Rhino Sanctuary in Sabah
The Sumatran Rhinoceros is now officially extinct in
Malaysia since Iman, a 25 year old female died in a sanctuary in Malaysia’s
Sabah state on 23 November 2019. Forced
by circumstances, Malaysian scientists, with the help of the Leibnitz Institute
for Zoo and Wildlife in Germany, were pursuing artificial reproduction
technology options. ART has so far shown
some degree of success in the White Rhinoceros Ceratotherium
simum and the Greater One-horned Rhinoceros Rhinoceros unicornis (Roth
2006; Hildebrandt et al. 2018). So much
is unknown about the Sumatran Rhinoceros’ biology, fertility, and reproduction
that these techniques seem less likely to succeed in the near future than
natural conception, on time to propagate the rhinos. In any case and with the possible extinction
of D. sumatrensis, it is important to
preserve cryogenically as much genetic material as possible—starting with
oocytes and gametes.
According to Agil et al.
(2008), Sumatran Rhinos have a low sperm concentration (oligozoospermia)
and a small volume of ejaculate. This
may be one more sumatrensis’
peculiarity or a cause of the Allee effect—e.g.,
anthropogenic alteration of population size leading to lack of genetic
diversity and demise. Recent scientific
research attempting to resurrect extinct species from cells has not been
considered here because it is still remote from guarantees and may be a
possible diversion to the present efforts to save the Sumatran Rhinoceros via
experimented methodologies.
The situation at Sumatran Rhino Sanctuary in Indonesia
The few remaining Sumatran Rhinos -(three males and
four females)-, are presently at SRS in order to breed them under the best
possible conditions with the potential for reintroduction of offspring to the
wild. At SRS they are carefully
monitored and kept under scientific protocols in a semi-wild condition. SRS is within Way Kambas
National Park and covers an area of about 100ha between Way Kanan
and Way Negarabatin, within an area of approximately
10,000ha.
Rhinos are kept in individual areas of 10–20 ha,
connected at the center to permit mating (Image
4). Every 20–25 days, the male is
introduced to the female (YABI 2019).
Harapan was born in Cincinnati Zoo on 29 April 2007 to female
Emi and male Ipuh, and was their third and last
calf. Harapan
spent time in three US zoos during his first eight years of life: Cincinnati
Zoo, White Oak Conservation Center in Florida, and
Los Angeles Zoo. He was moved to the
Sumatran Rhino Sanctuary (SRS) on 01 November 2015.
Bina, estimated to have been born around 1985, was one
of the last Sumatran Rhinos to be captured and relocated within Indonesia. She, who was about 18 years old at capture,
lived in an area of southern Sumatra called Bina Samakta,
in Bengkulu province. The region was
home to a significant population of Sumatran Rhinos, but the construction of
several villages, large oil palm plantations and a logging concession and
consequent rampant poaching, left the province with few rhinos.
Rosa, in late 2003, was rescued and brought to the
sanctuary. Rhino Protection Units
working in Bukit Barisan Selatan National Park
received reports from local villagers that a young female Sumatran Rhino had
frequently been observed walking along one of the main roads, crisscrossing the
park and browsing vegetation in villages around the park boundaries. She exhibits none of the shy, solitary
behaviour associated with her species.
Ratu, was born around 2000 in Way Kambas
NP, the protected area where the sanctuary is located. On 20 September 2005, rangers received reports
that this female Sumatran Rhinoceros had been spotted in Braja
Asri Village at about 04.00h. They rescued her and brought her to SRS.
Andalas, the Sumatran Rhino conceived and born at Cincinnati
Zoo, the first one produced in captivity in 112 years, is the result of
ground-breaking researches undertaken by American zoos, the Indonesian
Government and the Sumatran Rhino Sanctuary.
A worldwide news sensation, he was sent to Los Angeles Zoo when he was
two years old and then brought to SRS four years later.
Andatu was born in the early morning of Saturday, 23 June
2012 at the Sumatran Rhino Sanctuary in Way Kambas
National Park. His father is Andalas and his mother is Ratu.
Delilah was born in the early morning hours of
Thursday, 12 May 2016 at the Sumatran Rhino Sanctuary. Her father was also Andalas
and mother, Ratu (IRF 2018b).
Pahu, the female recently captured (25 November 2018) in
Kalimantan, is presently kept in a new facility on the island. Husbandry experts and veterinarians are
monitoring her health and assessing her breeding viability. They indicated she was in good health, fit
for transport to a designated sanctuary located less than 160km from capture
site, where she arrived safely.
Breaking news: Two Northern White rhino (Ceretotherium simum cottoni) in-vitro embryos were successfully created at Avantea Laboratories in Cremona, Italy. “Researchers
from Kenya, Italy, the Czech Republic, United States and Germany are still
fine-tuning the implantation procedure before the embryos are transferred into
a surrogate mother, but are hopeful a Northern White rhino calf can be born via
surrogacy within the next three years” (Wingard 2019).
Sumatran Rhinos conceived and born in controlled
environments
Only one Sumatran Rhinoceros had been conceived and
born ex situ before 13 September 2001, a hybrid between D. s. sumatrensis and D. s. lasiotis,
at the time considered full species. The
event took place at the zoo of Alipore, Calcutta, on 30 January 1889 (Sanyal 1889 in Rookmaaker et al.
1998). Cincinnati Zoo & Botanical
Gardens was the first facility to repeatedly breed D. s. sumatrensis
using a planned and managed reproduction protocol. In the nineties, scientists using
endocrinology analysis and ultrasonography set off research on the reproductive
physiology of the species (Schaffer et al. 1994; Roth et al. 1997). The major scientific breakthrough in the
discovery of induced ovulation in female Sumatran Rhinos, at the Center for Conservation and Research of Endangered Wildlife
in Cincinnati (Roth et al. 1998), produced the male Sumatran Rhinoceros Andalas (Roth et al. 2001; Roth 2002). Cincinnati Zoo’s breeding techniques
subsequently led to the birth of a female, Suci, on
30 July 2004 and another male, Harapan, on 29 April
2007.
The Cincinnati Zoo’s breeding pair was rescued from
the wild during the Indonesian-American Save the Sumatran Rhino project: Ipuh, the male, was captured on 23 July 1990, in Ipuh, Bengkulu, in southwestern Sumatra. He was transferred to San Diego Zoo on 10
April 1991, then to Cincinnati Zoo on 24 October 1991. Emi, the female, was captured as a subadult
on 6 March 1991 also in Ipuh. She was moved to Los Angeles Zoo on 23
November 1991, then to Cincinnati Zoo on 5 August 1995.
Success followed success and at the SRS two rhinos
were born: on 23 June 2012 the female Ratu gave birth
to the male Andatu, the first Sumatran Rhinoceros
conceived and born ex situ in southeastern Asia. Ratu mated with Andalas in March 2011 and took a 16-month pregnancy to
term. Andalas,
born at Cincinnati Zoo, had been brought to Indonesia from Los Angeles Zoo when
he was six years old.
Ratu mated again with Andalas on
22 January 2015 and took a 16-month pregnancy to term. On 12 May 2016, a female, Delilah (Image 6),
was born to the same pair (Arsan 2016) at the Sumatran Rhino Sanctuary. She weighed approximately 20kg at birth,
markedly less than her brother, Andatu, who weighed
27kg.
Considerations
Due to the extreme urgency to mitigate extinction of
the Sumatran Rhinoceros, ex situ management is a critical component in the
conservation of this critically endangered species.
Natural reproduction in a controlled environment can
be achieved through: a) optimum ex situ facilities, b) sorting out the
reproduction conundrum, c) best operated feeding protocol, and d) a deep
understanding of the species’ behavioural ecology.
When compared with other endangered species in
controlled environments, some aspects of the ecology and biology of the
Sumatran Rhinoceros are still poorly known.
Several essential elements of their ecology are based on scientific and
methodical evidence: the most outstanding finding was that the female is an
induced ovulator.
The Sumatran Rhino’s reproductive physiology is no longer a
mystery. Know-how, skills and means have
been difficult to acquire and marked with deep sorrows before this
extraordinary mammal prospered and its complete reproduction cycles succeeded,
resulting in five healthy calves growing to adults. These successes demonstrate the impact
scientific research can have on breeding endangered species. Even so, no rhino species breeding has been
consistent in controlled conditions so far, and their propagation continues to
be further investigated to identify the reasons for below optimal reproduction
(Roth et al. 2018).
Because they have poor eyesight, rhinos communicate
primarily by vocal and olfactory signals.
The Sumatran Rhinoceros is the most creative vocalizer among the extant
rhino species, and its vocalization has a number of similarities with that of
the Humpback Whale Megaptera novaeangliae
(Muggenthaler et al. 1993, 2003). Several characteristics of whales were
probably in place 25 million years ago at the latest and these traits have not
changed over millions of years (Slater et al. 2010). The many conversation expressions combined
with olfactory and auditory clues including infrasounds—extreme
frequencies that fall outside the normal response curve for the human
ear—trigger a variety of mental states (Wiseman 2014), some of which may
interfere with the rhino’s breeding activity.
For example, a male may subdue others sending “specific messages”.
Psychosomatic weakness resulting from emotional stress
can be a cause of severe disorders such as digestive and breeding
complications. These conditions should
also be investigated using the techniques available for the Black Rhinoceros Diceros bicornis
and the White Rhinoceros Ceratotherium simum (Carlstead et al.
2005), and new research carried out.
In future, an animal’s psycho-physical condition and
consciousness (Griffin 2001; Andrews 2015) will undoubtedly have a much broader
application in the management of several species for their relevant influence
over the animals’ welfare. The Sumatran
Rhinoceros has proved to be an extremely sensitive species, one of the most
difficult to adapt to controlled environment.
Nutrition
Nutritional aspects are of particular significance for
health and, perhaps, for the reproductive difficulties of Sumatran Rhinos in
captivity (Dierenfeld et al. 2000). Paul Reinhart, the Cincinnati Zoo’s Sumatran
Rhinos’ keeper at the time of the breeding successes says: “We didn’t know
much about the Sumatran Rhino, not many people did. We assumed you could keep them like Indian
rhino and like black [rhinos], feed [them] high-quality alfalfa grain, browse…
and that was not the case, not even remotely the case… The animals didn’t thrive in captivity until
we logged on to feeding them large amounts of browse, which we got from San
Diego and Florida.” (Hance 2018b).
The Sumatran Rhinoceros belongs to the leaf-eating
taxa, a relatively small number of species that depend strictly on the forest
as selectors of specific foliage on which their diet is based. These unusual animals are better identified as
folivores because a large number of species—the Black Rhinoceros included—among
ungulates, primates and other orders are recognized as browsers: generalist
vegetation eaters. Most folivores have
specialized stomachs, with their own kind of bacterial flora, to digest leaves,
which are abundant yet all-but-void of nutrition but very rich in leaf fibre
(also known as insoluble or long fibre) content. These rhinos consume foliage from a wide
range of rainforest tree species but at different intensities, indicating that
the Sumatran Rhinoceros is a selective folivore. Knowledge of general and seasonal food
preferences of this megafolivorous mammal allows a
better prediction of animal movements and therefore can assist in conservation
efforts in situ.
If the folivore’s extreme nutritional feeding pattern
is ignored, or confused with the browser’s habit, the risk of malnutrition in
folivores within controlled facilities will persist (Nardelli 2013). Most tropical wild leaves are low in iron
content, on the contrary of those from temperate arboreal species, mainly
broad-leaved deciduous and usually sourced to feed browsers in temperate ex
situ facilities; iron causes the deadly iron storage disease (ISD) or
hemochromatosis, a disorder resulting from deposition of excess iron into
insoluble iron clusters in soft tissue (Watanabe et al. 2016). Deciduous temperate forests also have a
higher leaf concentration of sodium, potassium, and calcium, hence the
consumption of saltlicks above all as source of sodium by several rainforest
mammals. Some Sumatran Rhinos died of
ISD in zoos, proving that presently this species is only safe feeding on its
native foliage. These high adaptations
lock folivores into their own world and make them vulnerable to changes.
The Sumatran Rhinoceros is an opportunistic feeder,
taking a mouthful here and there rather than feeding intensively and
systematically from one source. This
species’ cheek teeth are brachydont, adapted to retain a branch and pluck just
the leaves, nodding-turning its head.
The long-term supply of fresh leaves in large quantities and variety is
a priority in managing this species.
These rhinos prefer fast-growing, sun-loving plants found in forest
openings created by fallen trees, although the rhinos are also found in higher
density in primary forests.
From 1975 to 1980, Van Strien
(1985) sampled 150 plants, mainly dicotyledonous species, and established that
the Sumatran Rhinoceros does not eat fruit and monocotyledons (grasses and
sedges) including the wild banana (Musa sp.), a very tall “grass” common
in some areas. In 2016 Candra et al.
(2016) listed 211 species of plants consumed by Sumatran Rhinos and research by
Awaliah et al. (2018) found that the Sumatran Rhinos
in the SRS area feed on 61 plant species; leaves constitute 75–85 percent of
total food intake. The rhino keepers
supply 51 types (Image 7). At SRS each
rhino consumes daily 36–47 kg (x 7 = 252–329 kg), a massive burden for the
surrounding forest. Data on the type,
amount and proportion of the Sumatran Rhino’s favourite leaves are still
lacking or are not known with certainty, thus specific research activities need
to be persistent. It is however
known that leaves in tropical forests are defended by having low nutritional
quality, great toughness, and a wide variety of secondary metabolites (Coley
& Barone 1996) and because of the poor nutritional quality of mature
leaves, Sumatran Rhinos consume the more nutritious young leaves when possible.
Controlled environment
The quality of ex situ environments is fundamental for
successful conservation breeding. As
custodians of the last Sumatran Rhinos, we are responsible for ensuring their
limited habitats are safe and healthy for them to prosper.
The Sumatran Rhino Sanctuary located in Way Kambas National Park is home to the only Sumatran Rhinos
breeding in controlled environment in the world. This tiny population is pivotal in the
managed breeding program for the species’ recovery and for research. Built in 1996–1998 by the International Rhino
Foundation (IRF) and the Indonesian Rhino Foundation (YABI), the original SRS
facility was constructed within a vast, circular, single element split into a
number of enclosures to obtain triangular sections, bordering each other on two
sides—according to the standards of that time.
Each rhino resides in one subdivision of approximately 20ha of fenced
forest. The seven Sumatran Rhinos at the
SRS prosper in these large territories and receive state-of-the-art veterinary
care and nutrition (IRF 2018b). In
addition, SRS staff provide optimal care by physically checking the rhinos
regularly (Image 6); however, they have to be moved around (evidently some
paddocks are kept empty in turns) to allow the plants to re-grow (Bittel 2018).
Knowledge of the Sumatran Rhino’s consciousness is
lacking. Their conditioned responses to
stimuli should be researched and analyzed, as these
factors could assist in increasing survival and reproduction rates. From a series of photographs, videos and
personal observations, the presence of and interactions with human contacts
apparently are not causing visible stress on Sumatran Rhinos in the controlled
environment. What may not be possible to
recognize without specific studies could be the mutual stress induced by other
rhino(s) in adjacent enclosure(s), or other reasons. If animals are calm or
seem to be calm, it doesn’t mean that underlying tensions are not present. Zulfi Arsan, SRS
head veterinarian, reports: “Sumatran Rhinos are solitary animals that
become violent when housed together.” (Bittel 2018). In a former controlled breeding
centre, it was recommended to introduce only one female into a male enclosure
because of their solitary habit, to avoid serious injuries being inflicted on
the female (Zainuddin et al. 2005). Nevertheless, a short-term skirmish between
male and female is usual at the time of introducing the two for mating; in fact
such an event is widespread among a number of solitary species.
The SRS enclosures built in 1996 are adjacent to each
other; the animals likely consider these environments “confined”, considering
the views in this article, and thus these conditions can be causes of
undetected stress. With new and
up-to-date knowledge of the ecology of this species, new structures should be
located in separate areas, designed and created to meet the unique requirements
of the Sumatran Rhinoceros. New
controlled field centres for Sumatran Rhinos are likely better positioned when
they are separate and at distant locations, and with newly developed fenced
areas. At the same time, all known
rhinos, whether in situ or in controlled breeding centres, must be managed as
one population (Ellis 2013).
Keeping any animal species in a single location is an
unsafe, if not hazardous, practice (Nardelli 2016). Where a species’ population has been reduced
to isolated individuals or a segregated group, the need is critical to
establish at least a new, viable population, either in situ or ex situ or,
better, both, without procrastinating, to avoid the risk of spreading pathogens
over whole areas, or to prevent catastrophic events that can decimate the
remaining animals. The first concern
when planning is the health and safety of the rhinos. Disasters—whether close to the SRS such as in
2003 at the Sungai Dusun Conservation Centre in Malaysia, where a bacterial
infection wiped out all rhinos in two weeks (Vellayan
et al. 2004), or far away in the Democratic Republic of Congo in central
Africa, where in June 2012 armed rebels led by a poacher attacked the Okapi
Wildlife Reserve Epulu Station headquarters and
killed seven people and all 14 Okapi Okapia
johnstoni (Hance 2013)—represent hard experiences
that justify the construction of new facilities in distant areas, as suggested
by the Indonesian delegates at the Sumatran Rhinoceros Crisis Summit in
Singapore in 2013. The news that
pathogenic bacteria have been detected in Borneo Rhino Sanctuary and Sumatran
Rhino Sanctuary (Borneo Rhino Sanctuary Programme 2018; Wahyuni
et al. 2018), is a sign that innovative SRS logistic solutions are necessary to
increase safety standards.
Desiderata
Nutrition
The assessment of leaf nutritional status can bring
important and essential information for direct actions in the conservation
breeding of the Sumatran Rhinoceros.
Thus, in view of the recent decision by the Indonesian government to
count the remaining Sumatran Rhinos throughout the present distribution areas,
a comprehensive quantitative and qualitative vegetation survey and analysis of
the rhinos’ feeding leaves is highly recommended.
Sumatran Rhinos are believed to experience little
feeding competition but field studies so far lack sufficient examination of
competition from other taxa, except humans (e.g., Asiatic Elephant Elephas
maximus ssp., Asiatic Tapir Tapirus
indicus, other large and medium-sized terrestrial rainforest mammals). Terrestrial existence, large body size, and folivory are correlated (Palo & Robbins 1991). Van Strien (1985) reported: “From the total amount of
undergrowth (about ½ to 1½ kg per square meter) the leaves and stems suitable
as rhino food weighed between 260 and 520 grammes
(fresh weight) per square metre.
Re-growth of leaves and stems varied from 0.7 (in the forest) to 3.8
(near the river) grams per day per square metre. It seems from these figures that the average
production of browse suitable for the rhino is probably not more than 1 gram
per day per square metre. There are a
few hundreds of grams of browse standing on each square metre, but it takes a
long time, up to a year or so, for replacement”.
To better assess the consequences, future
investigations should include other connections to feeding competition such as
modification of ranging patterns, changes in activity, and decreased
fecundity. Information gained from such
studies may advance our current knowledge of Sumatran Rhinoceros ecology and
better define their conservation plans.
Best possible feeding in controlled environment, hopefully of an
increasing number of Sumatran Rhinos, may possibly become a handicap for the
optimum care of animals eating about 50kg daily of both specific and varied
kinds of foliage (Candra et al. 2016).
Suitable leaves may start to run out from the surroundings of a
congregate, highly populated breeding centre, their re-growth could be too slow
to fill the demand, or they may grow too high to be reached by the gatherers,
not to mention the ever-present logging predation. Furthermore, because folivores depend on such
an ephemeral food source and plant phenologies, this
may select for more elaborate life history traits. Isolating new enclosures and allowing large
distances between them will allow a larger quantity and variety of leaves to be
harvested for a much longer time, with ease and with less damage to the
vegetation that will re-grow in good health.
Controlled field conservation centres and units
From his experience as former curator of H&PL and
director of the Save the Sumatran Rhino project in Indonesia, the author
suggests that several vast forested areas measuring 20–50 ha apiece be fenced,
in the region of one percent of the natural home ranges of female–male Sumatran
Rhinos.
Two enclosures should be adjacent to each other
[shaped e.g., ],
to keep rhinos apart and to offer each animal sufficient and secluded
space. Such double units should be sited
several kilometres away (an expert veterinary team will assess the safest
distance) from each other, to avoid any physical and perceptive interference
between the rhinos.
The small portion where the two enclosures connect
will be the pair’s “meeting point”, which can be opened when managers decide to
allow male and female to mate, or closed to allow gestation, birth and the
young’s growth under natural physical and mental conditions. In a 2008 study, Terry Roth asserts: “... a
scientific method for accurately predicting when the female would be receptive
to the male was developed so that animals could be paired safely. Stimuli causing induced ovulation include the
physical act of coitus or mechanical stimulation simulating this, sperm and
pheromones. Sumatran females exhibit
unusual progesterone patterns when not mated”. SRS veterinarians monitor the female’s
ovarian follicular development via ultrasound examination before the animals
mate. When follicles reach 20–22 mm in
diameter, the time is right to put the two rhinos together (Terry Roth pers.
comm. April 2013).
Habitat protection
This new concept of controlled field
conservation centres should be considered because it contributes to
preserving not only the forest areas occupied by the enclosures but also of
much larger portions of habitat. The
forest surrounding the ‘controlled field units’ will have to be preserved for:
a) the rhino’s safety and welfare, b) the food reservoirs and buffer zones, and
c) the activity of the keepers, the food gatherers and the Rhino Protection
Units’ guards. As a result, a whole, much larger area can be saved once several
controlled field units become operational, ultimately making use of the entire
forest allocated to a new Sumatran Rhino sanctuary (Image 5). Such controlled and managed field conservation
centres could become central to the future protection of this rhino as well as
other species in need of human intervention.
Animal welfare
Hutchins & Kreger (2006) stated in 2006: “Perceiving,
retaining and replicating the species best conditions for their behaviour
performances are essential for their welfare, and this is particularly
important if conservation centres hope to reintroduce animals to the wild in
the future”. Animal welfare is a
fundamental consideration in curatorial management, and although animal
wellbeing can be measured systematically only to a certain degree (Hill &
Broom 2009), behavioural habits can be lost if the specific taxon’s natural
ecology is not comprehensively studied and properly applied. It is noteworthy that much of their welfare
depends on some people’s inborn endowment to interpret their needs (Aspinall
1976). Accordingly, ex situ wildlife
management and breeding is not a subject of university teaching.
“The welfare of any sentient animal is determined by
its individual perception of its own physical and emotional state” (Webster 2016).
How do Sumatran Rhinos obtain, process and exercise information if those
states and processes are not directly assessable? Behavioural ecology can shed light on issues
of cognition and on an ecological approach to cognition—environment
information, then cognitive planning, leading to behaviour—should provide the
evidence.
For the purpose of biological conservation, several
aspects of management are important and poor quarters and environments are
responsible for permanent changes in behaviour and physiology (Hofer & East
1998).
Housing Sumatran Rhinos in a species-appropriate area
where they are able to perform normal activities and make independent choices
should be considered fundamental for their well-being. To that end, managers could go to greater
lengths to provide their animals items (e.g., mud wallows and saltlicks) that
encourage exploration of a greater diversity of behaviours and that encourage
maximal use of space. A further
possibility is corridors that allow animals to move from one space to
another. Not only does this provide the
option for animals to choose one location over another, but it also increases
the space available for them to roam, and it enlarges the diversity of stimuli
that the animal can possibly experience in each of the different settings.
Behavioural ecology
Several animal species communicate through all their
senses including by means humans do not have.
In recent years, the study of animal communication has expanded rapidly
as has information on their consciousness (Bekoff et
al. 2002) and has allowed the discovery of mesmerizing phenomena. For example, the Sumatran Rhinoceros emits an
infrasound whistle followed by a sharp burst of air that can travel for
kilometres (Muggenthaler 2003). Such complex communication, infrasounds included, in addition to the known capacity of
the sensory organs to influence cognitive activities result in behaviour
remarkably similar to what humans define as social behaviour, although the
Sumatran Rhinoceros is solitary and generally avoids contact with other rhinos
in nature.
Reproductive competition occurs when an individual’s
capacity to conceive has diminished due to the presence of a conspecific. Most animal species resolve this problem by
living solitarily (Emlen 1982): one more reason to
manage the Sumatran Rhinos separately in several controlled field centres. Another aspect to consider is the behaviour
of adult breeding males in the presence of sub-adult and/or adult non-breeding
males; a psychological submission may develop, under controlled conditions,
which could inhibit the non-breeding males.
In fact, dominant male rhinos were present in situ during Borner (1979) and van Strien
(1985) field studies, as reported by the authors. Furthermore, in spite of “social” designates
to do with more than one individual (Waal & Tyack 2003)—the behaviour of a
pair of animals may even be called social—socialising induces stress.
Stress in this context means the effects resulting
from causes of various origins in rhinos, which interrupt homeostasis and cause
harm because they diminish biological functions and ultimately result in
reduced health conditions and a negative factor that favours the action of
glucocorticoids, which cause infertility in mammals (Broom & Johnson
1993). Measuring faecal glucocorticoids,
or their metabolites, may be useful for well-being studies in controlled
environments—especially in assessing short-term responses to stressors e.g.
capture, transportation and translocation are important stressors—and can
contribute non-invasively to the work of biologists (Metrione
& Harder 2011).
Carlstead & Brown (2005) presented evidence showing that
social tension may cause chronic stress in the Black Rhinoceros and the White
Rhinoceros, and established that non-cycling female rhinoceroses had more
variable corticoid concentrations and higher rates of stereotypic pacing, an
indicator of high stress levels. This factor
gives the managed population a sustainability struggle that is observed in each
species. Psychosomatic weaknesses, a
probable cause of severe disorders, should also be investigated using the
techniques available for the Black Rhinoceros and the White Rhinoceros (Carlstead & Brown 2005), and new research carried out.
Ex situ conservation centres with more than one female
Black Rhinoceros have a lower reproductive rate and a later age of first
birth. Probably, there is a
density-dependent restraining effect on breeding function among females in
confined environments (Carlstead et al.
1999a,b). A physiological evaluation of
welfare in managed animals can be obtained non-invasively through analysis of
adrenal hormones in saliva. Adrenalin
hormones measure activity in the sympathetic–adrenal medullary system and in
the hypothalamic–pituitary–adrenocortical system (Palme 2012). Salivary corticosterone concentrations can
determine stress in White rhinos (Schmidt & Sachser
2000).
A survey study conducted on Black rhinos ex situ
surprisingly found that more aggression and assertiveness contributed
positively to a female’s chances of breeding (Carlstead
et al. 1999a,b). The reproductive rates
of Black Rhinoceros and White Rhinoceros in controlled environments are
unsustainably low. Evidence shows that
to a large extent social signals may cause chronic stress in rhinos, and this
element contributes to the sustainability problems observed in each species of
managed populations (Carlstead & Brown 2005; Metrione et al. 2007). The concentration of glucocorticoids (or
their metabolites) can be measured in various body fluids or excreta. Above all, faecal samples offer the advantage
that they can be easily collected and this procedure is feedback free. Thus, such methods are a valuable tool in a variety of research
fields such as animal welfare in handling, housing and transport and also in
ethological and environmental studies.
Scientific research on the behaviour of the Sumatran
Rhinoceros should be expanded to include cognitive ethology—the comparative
study of mental phenomena—including both conscious and unconscious mental
states. A lot of effort is expended on
the care of animals but only rarely is the inner world of those sentient beings
well thought-out in strategic planning.
Conclusions
There is reason to believe that the Sumatran
Rhinoceros can continue to exist, providing that animals will still be around
for a sufficient time to be rescued, or survivors that have lost contact with
each other are not all genetically or reproductively ruined. Populations lose genetic diversity at a rate
proportional to the inverse of their effective population size (Frankhman 1996), thus the surviving, small, D. sumatrensis populations are rapidly losing genetic
diversity through drift (random loss of alleles across generations). To re-establish viable populations in numbers
sufficient to maintain genetic diversity, it is imperative not only to capture
the few remaining individuals, wherever they may be, but to induce them
to breed under the best conditions as a matter of urgency.
Food preferences of Sumatran Rhinoceros probably
trigger short-term movements of individuals outside their home ranges,
conservation actions should therefore aim at enlargements and connectivity of
its habitats utilizing controlled field centres. The species’ selective feeding habits may
result in individuals moving into areas with highly preferred food resources,
which can be areas of high mortality risks, once known to poachers. Habitat connectivity projects should pinpoint
areas that allow these rhinos to access higher elevated areas, secluded and
less accessible to humans.
With the rapid
destruction of tropical forests and the threat of global climate change, a
greater understanding of the importance of what has worked and what would work,
is essential to the preservation of the megafolivorous
Sumatran Rhinoceros.
In controlled environments, animal species which are
difficult to observe in the wild can increase our knowledge of ecologic aspects
that influence their habitat utilization within fragmented landscapes and can
assist in animal husbandry and the planning of current and future conservation
efforts. It is essential and urgent to
match ongoing efforts for in situ protection with ex situ breeding, and to
optimize this species’ peculiar requirements inside strictly protected areas
and in controlled field centres. The
critically endangered Sumatran Rhino is a perfect example of the need for
conservation measures that follow a One Plan Approach paradigm. The One Plan Approach, initially proposed by
the IUCN SSC Conservation Planning Specialist Group (CPSG), considers all
populations of the species, in situ and ex situ, under different conditions of
management, engaging all responsible parties and all available resources from
the very start of any species conservation planning initiative, as per Byers et
al. (2013): “The One Plan approach aims to establish new partnerships,
ensure that intensively managed populations are as useful as possible to
species conservation, increase the level of trust and understanding among
conservationists across all conditions of management of a species and
accelerate the evolution of species planning tools. Integrated species planning is not a new
concept. Such holistic conservation
efforts have led to several well-known conservation successes, from Golden lion
tamarins in Brazil to Puerto Rican Crested toads in the Caribbean to Arabian
oryx in the Middle East”.
The Sumatran Rhinoceros is of special interest
because, with the Javan Rhinoceros Rhinoceros
sondaicus, it is one of the largest mammal
species that depends on undisturbed rainforest and for that reason can be
regarded as an important indicator species.
Despite the vigorous attempts by a handful of people to protect it, time
is running out for the Sumatran Rhinoceros: a foremost phylum-genetic diversity
loss (Davis et al. 2018). In the present
status of wildlife, it is difficult to reconcile the actions of leaving a
species to become extinct or allowing individuals to solely survive in ex situ
breeding centres, albeit with unavoidable negative experiences. The Sumatran Rhinoceros represents the
emblematic example of such a perplexing state of affairs.
Is saving the Sumatran Rhino mission possible? Yes!
It will require a collaborative effort, following hard-and-fast rules,
and optimal management conditions.
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