Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...
n island of
Sumatra
Sumatra () is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the list of islands by area, sixth-largest island in the world at 482,286.55 km2 (182,812 mi. ...
. It is the only surviving tiger population in the Sunda Islands, where the
Bali
Bali (English:; Balinese language, Balinese: ) is a Provinces of Indonesia, province of Indonesia and the westernmost of the Lesser Sunda Islands. East of Java and west of Lombok, the province includes the island of Bali and a few smaller o ...
and
Javan tiger
The Javan tiger was a ''Panthera tigris sondaica'' population native to the Indonesian island of Java. It was one of the three tiger populations that colonized the Sunda Islands during the last glacial period 110,000–12,000 years ago. It used t ...
s are extinct.Sequences from complete mitochondrial genes of 34 tigers support the hypothesis that Sumatran tigers are diagnostically distinct from mainland subspecies. In 2017, the Cat Classification Task Force of the Cat Specialist Group revised felid taxonomy and recognizes the living and extinct tiger populations in Indonesia as '' P. t. sondaica''.
Taxonomy
''Felis tigris sondaicus'' was the
scientific name
In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...
proposed by
Coenraad Jacob Temminck
Coenraad Jacob Temminck (; 31 March 1778 – 30 January 1858) was a Dutch people, Dutch patrician, Zoology, zoologist and museum director.
Biography
Coenraad Jacob Temminck was born on 31 March 1778 in Amsterdam in the Dutch Republic. Fro ...
in 1844 for a tiger specimen from
Java
Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...
.
''Panthera tigris sumatrae'' was proposed by
Reginald Innes Pocock
Reginald Innes Pocock, (4 March 1863 – 9 August 1947) was a British zoologist.
Pocock was born in Clifton, Bristol, the fourth son of Rev. Nicholas Pocock and Edith Prichard. He began showing interest in natural history at St. Edward's ...
in 1929, who described a skin and a
skull
The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate.
In the human, the skull comprises two prominent ...
of a tiger zoological specimen from Sumatra.
The skull and pelage pattern of tiger specimens from Java and Sumatra do not differ significantly.
''P. t. sondaica'' is therefore considered the valid name for the living and extinct tiger populations in Indonesia.
Evolution
Analysis of
DNA
Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...
is consistent with the hypothesis that Sumatran tigers became isolated from other tiger populations after a rise in sea level that occurred at the
Pleistocene
The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
to
Holocene
The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...
transition about 12,000–6,000 years ago. In agreement with this evolutionary history, the Sumatran tiger is genetically isolated from all living mainland tigers, which form a distinct group closely related to each other. The isolation of the Sumatran tiger from mainland tiger populations is supported by multiple unique characters, including two diagnostic
mitochondrial DNA
Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondrion, mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the D ...
nucleotide sites, ten mitochondrial DNA
haplotype
A haplotype (haploid genotype) is a group of alleles in an organism that are inherited together from a single parent.
Many organisms contain genetic material (DNA) which is inherited from two parents. Normally these organisms have their DNA orga ...
s and 11 out of 108 unique
microsatellite
A microsatellite is a tract of repetitive DNA in which certain Sequence motif, DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. Microsatellites occur at thousands of locations within an organ ...
allele
An allele is a variant of the sequence of nucleotides at a particular location, or Locus (genetics), locus, on a DNA molecule.
Alleles can differ at a single position through Single-nucleotide polymorphism, single nucleotide polymorphisms (SNP), ...
s. The relatively high genetic variability and the phylogenetic distinctiveness of the Sumatran tiger indicates that the
gene flow
In population genetics, gene flow (also known as migration and allele flow) is the transfer of genetic variation, genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalent ...
between island and mainland populations was highly restricted.
Characteristics
The Sumatran tiger was described based on two zoological specimens that differed in skull size and striping pattern from
Bengal
Bengal ( ) is a Historical geography, historical geographical, ethnolinguistic and cultural term referring to a region in the Eastern South Asia, eastern part of the Indian subcontinent at the apex of the Bay of Bengal. The region of Benga ...
and
Javan tiger
The Javan tiger was a ''Panthera tigris sondaica'' population native to the Indonesian island of Java. It was one of the three tiger populations that colonized the Sunda Islands during the last glacial period 110,000–12,000 years ago. It used t ...
specimens. It is darker in fur colour and has broader stripes than the Javan tiger. Stripes tend to dissolve into spots near their ends, and on the back, flanks and hind legs are lines of small, dark spots between the regular stripes. The frequency of stripes is higher than in other subspecies.
Males have a prominent ruff, which is especially marked in the Sumatran tiger.
The Sumatran tiger is one of the smallest tigers. Males measure between the pegs in head-to-body length, with the greatest skull length of and weigh . Females weigh and measure in length between the pegs with a greatest length of skull of .
Distribution and habitat
The Sumatran tiger persists in small and fragmented populations across Sumatra, from
sea level
Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...
in the coastal lowland forest of Bukit Barisan Selatan National Park on the southeastern tip of Lampung Province to in mountain forests of Gunung Leuser National Park in Aceh Province. It is present in 27 habitat patches larger than , which cover . About a third of these patches are inside protected areas.
Sumatran tigers prefer lowland and hill forests, where up to three tigers live in an area of ; they use non-forest habitats and human-dominated landscapes at the fringes of protected areas to a lesser degree.
In 1978, the Sumatran tiger population was estimated at 1,000 individuals, based on responses to a questionnaire survey. In 1985, a total of 26 protected areas across Sumatra containing about 800 tigers were identified. In 1992, an estimated 400–500 tigers lived in five Sumatran national parks and two
protected areas
Protected areas or conservation areas are locations which receive protection because of their recognized natural or cultural values. Protected areas are those areas in which human presence or the exploitation of natural resources (e.g. firewoo ...
. At that time, the largest population unit comprised 110–180 individuals in Gunung Leuser National Park.
As of 2011, the tiger population in Kerinci Seblat National Park in central Sumatra comprised 165–190 individuals, which is more than anywhere else on the island. The park has the highest tiger occupancy rate of Sumatra's protected areas, with 83% of the park showing signs of tigers.
Sumatra's total tiger population was estimated at 618 ± 290 individuals in 2017.
Ecology and behaviour
Sumatran tigers strongly prefer uncultivated forests and make little use of plantations of
acacia
''Acacia'', commonly known as wattles or acacias, is a genus of about of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa, South America, and Austral ...
and
oil palm
''Elaeis'' () is a genus of palms, called oil palms, containing two species, native to Africa and the Americas. They are used in commercial agriculture in the production of palm oil.
Description
Mature palms are single-stemmed, and can gro ...
even if these are available. Within natural forest areas, they tend to use areas with higher elevation, lower annual rainfall, farther from the forest edge, and closer to forest centres. They prefer forest with dense understory cover and steep slope, and they strongly avoid forest areas with high human influence in the forms of encroachment and settlement. In acacia plantations, they tend to use areas closer to water and prefer areas with older plants, more
leaf litter
Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...
, and thicker subcanopy cover. Tiger records in oil palm plantations and rubber plantations are scarce. The availability of adequate vegetation cover at the ground level serves as an environmental condition fundamentally needed by tigers regardless of the location. Without adequate understory cover, tigers are even more vulnerable to persecution by humans. Human disturbance-related variables negatively affect tiger occupancy and habitat use. Variables with strong impacts include settlement and encroachment within forest areas,
logging
Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidder, skidding, on-site processing, and loading of trees or trunk (botany), logs onto logging truck, trucksCamera trapping surveys conducted in southern
Riau
Riau (Jawi script, Jawi: ) is a Provinces of Indonesia, province of Indonesia. It is located on the central eastern coast of the island of Sumatra, and extends from the eastern slopes of the Barisan Mountains to the Malacca Strait, including s ...
Major threats include habitat loss due to expansion of palm oil plantations and planting of acacia plantations, prey-base depletion, and illegal trade primarily for the domestic market.
Conflicts with humans are another major threat to the Sumatran tiger. Poachers target tigers with wire snares, and they are also inadvertently caught in traps set by deer hunters and farmers attempting to control crop raids from wild boar.
Tigers need large contiguous forest blocks to thrive. Between 1985 and 1999, forest loss within Bukit Barisan Selatan National Park averaged 2% per year. A total of of forest disappeared inside the park, and were lost in a 10-km buffer, eliminating forest outside the park. Lowland forest disappeared faster than
montane forest
Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...
, and forests on gentle slopes disappeared faster than forests on steep slopes. Most forest conversions resulted from agricultural development, leading to predictions that by 2010, 70% of the park will be in agriculture. Camera-trap data indicated avoidance of forest boundaries by tigers. Classification of forest into core and peripheral forest based on mammal distribution suggests that by 2010, core forest area for tigers will be fragmented and reduced to 20% of the remaining forest.
Sumatra's largest tiger population in Kerinci Seblat National Park is threatened by a high rate of
deforestation
Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...
in its outer regions. Drivers are an unsustainable demand for natural resources created by a human population with the highest rate of growth in Indonesia, and a government initiative to increase tree-crop plantations and high-intensity commercial
logging
Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidder, skidding, on-site processing, and loading of trees or trunk (botany), logs onto logging truck, trucksgreenhouse gas emissions
Greenhouse gas (GHG) emissions from human activities intensify the greenhouse effect. This contributes to climate change. Carbon dioxide (), from burning fossil fuels such as coal, petroleum, oil, and natural gas, is the main cause of climate chan ...
, playing a part in anthropogenic climate change, thus further adding to environmental pressures on endangered species. Climate-based movement of tigers northwards may lead to increased conflict with people. From 1987 to 1997, Sumatran tigers reportedly killed 146 people and at least 870 livestock. In West Sumatra, Riau, and Aceh, a total of 128 incidents were reported; 265 tigers were killed and 97 captured in response, and 35 more tigers were killed from 1998 to 2002. From 2007 to 2010, the tigers caused the death of 9 humans and 25 further tigers were killed.
In 1997, an estimated 53 tigers were killed by poachers and their parts sold throughout most of northern Sumatra. Numbers for all of Sumatra are likely to be higher. Farmers killed many of the tigers to prevent livestock losses. They sold them to gold and souvenir shops, and pharmacies. In 2006, wildlife markets were surveyed in 28 cities and nine seaports in seven Sumatran provinces; 33 of 326 retail outlets offered tiger parts like skins, canines, bones, and whiskers. Tiger bones fetched the highest average price of US$116 per kg, followed by canines. There is evidence that tiger parts are smuggled out of Indonesia. In July 2005, over of tiger bones and 24 skulls were confiscated in
Taiwan
Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...
in a shipment from
Jakarta
Jakarta (; , Betawi language, Betawi: ''Jakartè''), officially the Special Capital Region of Jakarta (; ''DKI Jakarta'') and formerly known as Batavia, Dutch East Indies, Batavia until 1949, is the capital and largest city of Indonesia and ...
.
In 2013–2014, Kerinci Seblat National Park experienced an upsurge in poaching, with the highest annual number of snare traps being removed for a patrol effort similar to previous years. Evidence is scarce and misunderstood on whether the strategies implemented to diminish poaching are succeeding despite the investment of millions of dollars annually into conservation strategies.
In provincially-managed forests in
Aceh
Aceh ( , ; , Jawi script, Jawoë: ; Van Ophuijsen Spelling System, Old Spelling: ''Atjeh'') is the westernmost Provinces of Indonesia, province of Indonesia. It is located on the northern end of Sumatra island, with Banda Aceh being its capit ...
province, Sumatran tigers are threatened by poaching due to insufficient or nonexistent ranger patrols.
Conservation
''Panthera tigris'' is listed on CITES Appendix I. Hunting is prohibited in Indonesia.
In 1994, the Indonesian Sumatran Tiger Conservation Strategy addressed the potential crisis that tigers faced in Sumatra. The Sumatran Tiger Project (STP) was initiated in June 1995 in and around the Way Kambas National Park to ensure the long-term viability of wild Sumatran tigers and to accumulate data on tiger life-history characteristics vital for the management of wild populations. By August 1999, the teams of the STP had evaluated 52 sites of potential tiger habitat in Lampung Province, of which only 15 were intact enough to contain tigers. In the framework of the STP, a community-based conservation programme was initiated to document the tiger-human dimension in the park to enable conservation authorities to resolve tiger-human conflicts based on a comprehensive database rather than anecdotes and opinions.
In 2007, the Indonesian Forestry Ministry and Safari Park established cooperation with the Australia Zoo for the conservation of Sumatran tigers and other endangered species. The program includes conserving Sumatran tigers and other endangered species in the wild, efforts to reduce conflicts between tigers and humans, and rehabilitating Sumatran tigers and reintroducing them to their natural habitat.
Indonesia's struggle with conservation has caused an upsurge in political momentum to protect and conserve wildlife and biodiversity. In 2009, Indonesia's president committed to substantially reduce deforestation, and policies across the nation requiring spatial plans that would be environmentally sustainable at national, provincial, and district levels.
Between 2005 and 2015, about US$210 million have been invested into tiger law-enforcement activities that support forest ranger patrols, as well as the implementations of front-line law-enforcement activities by the Global Tiger Recovery Plan, which aims to double the number of wild tigers by 2020.
In November 2016, Batu Nanggar Sanctuary was opened in North Padang Lawas Regency,
North Sumatra
North Sumatra () is a Provinces of Indonesia, province of Indonesia located in the northern part of the island of Sumatra. Its capital and largest city is Medan on the east coast of the island. It borders Aceh to the northwest, Riau to the sou ...
for conservation of Sumatran wildlife.
An interview survey among 600 consumers revealed that most were willing to pay consistently more for a "tiger-friendly" produced good if this product would be conducive to Sumatran tiger conservation.
In captivity
As of 2013, about 375 captive Sumatran tigers were listed in the global
studbook
A breed registry, also known as a herdbook, studbook or register, in animal husbandry, the hobby of animal fancy, is an official list of animals within a specific breed whose parents are known. Animals are usually registered by their breeders w ...
and management plan, with 50 of them housed in 14 zoos in Australia and
New Zealand
New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
. All of them were offspring of 15 founders. Fourteen cubs showed
congenital
A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...
vestibular system
The vestibular system, in vertebrates, is a sensory system that creates the sense of balance and spatial orientation for the purpose of coordinating motor coordination, movement with balance. Together with the cochlea, a part of the auditory sys ...
dysfunctions such as
ataxia
Ataxia (from Greek α- negative prefix+ -τάξις rder= "lack of order") is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in e ...
,
strabismus
Strabismus is an eye disorder in which the eyes do not properly align with each other when looking at an object. The eye that is pointed at an object can alternate. The condition may be present occasionally or constantly. If present during a ...
, nystagmus, head tilting and falling that resolved when they were two years old. The cause for this disorder is most likely their close genetic relation and
inbreeding
Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely genetic distance, related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genet ...