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Horsfield's tarsier (''Cephalopachus bancanus''), also known as the western tarsier, is the only species of
tarsier Tarsiers ( ) are haplorhine primates of the family Tarsiidae, which is itself the lone extant family within the infraorder Tarsiiformes. Although the group was once more widespread, all of its species living today are found in Maritime Southeast ...
in the genus ''Cephalopachus''. Named for American naturalist
Thomas Horsfield Thomas Horsfield (May 12, 1773 – July 24, 1859) was an American physician and natural history, naturalist who worked extensively in Indonesia, describing numerous species of plants and animals from the region. He was later a curator of the Eas ...
, it occurs on
Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and eas ...
,
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 sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...
and nearby islands and is, like other members of the group, entirely nocturnal.


Taxonomy

Although Horsfield's tarsier was usually placed in the genus ''
Tarsius ''Tarsius'' is a genus of tarsiers, small primates native to islands of Southeast Asia. Until 2010, all tarsier species were typically assigned to this genus, but a revision of the family Tarsiidae restored the generic status of ''Cephalopach ...
'' with all other living tarsiers, it is quite distinct from the
Philippine tarsier The Philippine tarsier (''Carlito syrichta''), known locally as ''mawumag'' in Cebuano and other Visayan languages, and ''magô'' in Waray, is a species of tarsier endemic to the Philippines. It is found in the southeastern part of the archip ...
and the various tarsiers of
Sulawesi Sulawesi (), also known as Celebes (), is an island in Indonesia. One of the four Greater Sunda Islands, and the world's eleventh-largest island, it is situated east of Borneo, west of the Maluku Islands, and south of Mindanao and the Sulu Ar ...
and nearby islands; therefore, scientists have placed it in a separate genus, ''Cephalopachus''. The taxonomy of this species is in doubt, with some subspecies considered unsure. In fact, over 20 years few studies have been done on ''C. bancanus'' and a taxonomic revision based upon intensive and systematic field surveys is overdue. The
IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
believes that these subspecies should be treated as distinct and named as separate taxa until more definitive evidence is available. When splitting the species into its own genus,
Colin Groves Colin Peter Groves (24 June 1942 – 30 November 2017) was a British-Australian biologist and anthropologist. Groves was Professor of Biological Anthropology at the Australian National University in Canberra, Australia. Education Born in Englan ...
and Myron Shekelle recognized the ''natunensis'' population as a distinct subspecies. There are four recognized subspecies of Horfield's tarsier: * ''Cephalopachus bancanus bancanus'' * ''Cephalopachus bancanus saltator'' — Belitung Island tarsier * ''Cephalopachus bancanus borneanus'' — Bornean tarsier * ''Cephalopachus bancanus natunensis'' — Natuna Islands tarsier


Physical description

The
pelage Fur is a thick growth of hair that covers the skin of mammals. It consists of a combination of oily #Guard hair, guard hair on top and thick #Down hair, underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as ...
coloration ranges from pale-olive or reddish brown to pale or dark grey-brown, possibly varying with age. Based on 12 collected specimens, the range measurement from head to body is 121–154 mm. Horsfield's tarsier has an extremely long tail which can reach 181 to 224 mm and is hairless except for tufts of hair at the end. This species has two grooming
claws A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus ...
on each foot. The fingers are very long and have pads on the tips. The toes have flattened nails except for the second and third toes on hind feet, which bear claw-like nails. It has large eyes which do not reflect light. The membranous ears are slender and almost bare. The molars of this species have high-cusps and are almost tritubercular. The dental formula of Horsfield's tarsier is 2:1:3:3 on the upper jaw and 1:1:3:3 on the lower jaw.


Habitat and distribution

Horsfield's tarsier is found in Southern
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 sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...
,
Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and eas ...
and nearby islands. The Bornean subspecies, ''C. b. borneanus'', is known from many lowland sites in
Sabah Sabah () is a States and federal territories of Malaysia, state of Malaysia located in northern Borneo, in the region of East Malaysia. Sabah borders the Malaysian state of Sarawak to the southwest and the North Kalimantan province of Indone ...
,
Brunei Brunei ( , ), formally Brunei Darussalam ( ms, Negara Brunei Darussalam, Jawi alphabet, Jawi: , ), is a country located on the north coast of the island of Borneo in Southeast Asia. Apart from its South China Sea coast, it is completely sur ...
,
Sarawak Sarawak (; ) is a States and federal territories of Malaysia, state of Malaysia. The largest among the 13 states, with an area almost equal to that of Peninsular Malaysia, Sarawak is located in northwest Borneo Island, and is bordered by the M ...
and West
Kalimantan Kalimantan () is the Indonesian portion of the island of Borneo. It constitutes 73% of the island's area. The non-Indonesian parts of Borneo are Brunei and East Malaysia. In Indonesia, "Kalimantan" refers to the whole island of Borneo. In 2019, ...
and above 900m in the Kelabit uplands in Northern
Sarawak Sarawak (; ) is a States and federal territories of Malaysia, state of Malaysia. The largest among the 13 states, with an area almost equal to that of Peninsular Malaysia, Sarawak is located in northwest Borneo Island, and is bordered by the M ...
. Other records show it from Kutai and Peleben in East
Kalimantan Kalimantan () is the Indonesian portion of the island of Borneo. It constitutes 73% of the island's area. The non-Indonesian parts of Borneo are Brunei and East Malaysia. In Indonesia, "Kalimantan" refers to the whole island of Borneo. In 2019, ...
and Tanjung Maruwe in Central
Kalimantan Kalimantan () is the Indonesian portion of the island of Borneo. It constitutes 73% of the island's area. The non-Indonesian parts of Borneo are Brunei and East Malaysia. In Indonesia, "Kalimantan" refers to the whole island of Borneo. In 2019, ...
. This species can live in both primary and secondary forests, and it also lives in forests along the coasts or on the edge of plantations.


Behaviour and ecology

Horsfield's tarsier is a
nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...
species. It sleeps alone during the day in a tangle of vines or creepers at a height of 3.5 to 5 meters. This species prefers to sleep, rest, or remain stationary on perches that are angled 5 degrees from the vertical tree trunks, 1 to 4 cm in diameter, and it sleeps solitarily. Before sunset, Horsfield's tarsier will wake up and wait 10 to 20 minutes before moving around the understory and spending 1.5 to 2 hours of the night foraging for food. Horsfield's tarsier can be found from ground level up to a height of 7m or more in the understory. This species is carnivorous. It mainly eats
insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of j ...
such as
beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
s,
grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshopp ...
s,
katydids Insects in the family Tettigoniidae are commonly called katydids (especially in North America), or bush crickets. They have previously been known as "long-horned grasshoppers". More than 8,000 species are known. Part of the suborder Ensifera, t ...
,
cockroach Cockroaches (or roaches) are a paraphyletic group of insects belonging to Blattodea, containing all members of the group except termites. About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known as ...
es,
butterflies Butterflies are insects in the macrolepidopteran clade Rhopalocera from the Order (biology), order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The ...
,
moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
s,
praying mantis Mantises are an order (Mantodea) of insects that contains over 2,400 species in about 460 genera in 33 families. The largest family is the Mantidae ("mantids"). Mantises are distributed worldwide in temperate and tropical habitats. They ha ...
,
ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22 ...
s, phasmids, and
cicada The cicadas () are a superfamily, the Cicadoidea, of insects in the order Hemiptera (true bugs). They are in the suborder Auchenorrhyncha, along with smaller jumping bugs such as leafhoppers and froghoppers. The superfamily is divided into two ...
s, but also will eat small
vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
such as bats (
Chiroptera Bats are mammals of the Order (biology), order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in fli ...
) including members of the genus ''
Taphozous ''Taphozous'' is a genus of the family Emballonuridae. The wide distribution of the genus includes several regions of Australia, Indonesia, Papua New Guinea and Africa. ''Taphozous'' comes from the Greek τάφος, meaning "a tomb". The common n ...
'', the lesser short-nosed fruit bat (''
Cynopterus brachyotis The lesser short-nosed fruit bat (''Cynopterus brachyotis'') is a species of megabat within the family Pteropodidae. It is a small bat that lives in South Asia and Southeast Asia. It weighs between , and measures . It occurs in many types of habi ...
''), and the spotted-winged fruit bat ('' Balionycteris maculata''), and snakes, of which poisonous snakes have been found to be consumed. For example, the poisonous snake '' Maticora intestinalis'' was found to be hunted for by this species. This species was also found to consume
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
s, including:
spiderhunter The spiderhunters are birds of the genus ''Arachnothera'', part of the sunbird family Nectariniidae. The genus contains thirteen species found in the forests of south and southeastern Asia. They are large representatives of the sunbird family, wi ...
s,
warbler Various Passeriformes (perching birds) are commonly referred to as warblers. They are not necessarily closely related to one another, but share some characteristics, such as being fairly small, vocal, and insectivorous. Sylvioid warblers Th ...
s,
kingfisher Kingfishers are a family, the Alcedinidae, of small to medium-sized, brightly colored birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species found in the tropical regions of Africa, Asia, and Oceania, ...
s, and
pitta Pittas are a family, Pittidae, of passerine birds found in Asia, Australasia and Africa. There are thought to be 40 to 42 species of pittas, all similar in general appearance and habits. The pittas are Old World suboscines, and their closest re ...
s. It locates prey primarily by sound and catches the prey with its hands when foraging. The prey items get killed by bites to the back of the neck and the eyes are shut when attacking. It will consume the prey starting with the head and working its way down the body. This species gets water both by drinking from a pool or stream, and by licking drops from bamboo leaves or from trunks of trees when water is running down the bark. Horsfield's tarsier is a host of the
acanthocephala Acanthocephala (Greek , ', thorn + , ', head) is a phylum of parasitic worms known as acanthocephalans, thorny-headed worms, or spiny-headed worms, characterized by the presence of an eversible proboscis, armed with spines, which it uses to p ...
n intestinal parasite '' Moniliformis tarsii''. Horsfield's tarsier, like all tarsiers, is a vertical clinger and leaper known for its extraordinary leaping abilities. An individual will mainly support itself with its feet and the tail exerts enough force to hold the individual in place without using the hands much because of the pads located on the feet. Except when resting, the hands are usually placed no higher than its nose. The hands are only placed higher up to maintain the position of the individual. Other modes of locomotion used by the species include climbing, quadrupedal walking, hopping and "
cantilever A cantilever is a rigid structural element that extends horizontally and is supported at only one end. Typically it extends from a flat vertical surface such as a wall, to which it must be firmly attached. Like other structural elements, a canti ...
ing." Horsfield's tarsier is
monogamous Monogamy ( ) is a form of Dyad (sociology), dyadic Intimate relationship, relationship in which an individual has only one Significant other, partner during their lifetime. Alternately, only one partner at any one time (Monogamy#Serial monogamy, ...
, with a copulation frequency during estrus of once per night.
Courtship Courtship is the period wherein some couples get to know each other prior to a possible marriage. Courtship traditionally may begin after a betrothal and may conclude with the celebration of marriage. A courtship may be an informal and private m ...
call Call or Calls may refer to: Arts, entertainment, and media Games * Call, a type of betting in poker * Call, in the game of contract bridge, a bid, pass, double, or redouble in the bidding stage Music and dance * Call (band), from Lahore, Paki ...
s are performed by the male and he emits 2-3 chirrups while opening and closing the mouth. This call happens within 5 minutes of looking at the female. Once the male gives his courtship call, if the female is receptive, she will perform genital displays to him. If the female is not in estrus, she will emit an
agonistic An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the agon ...
call which is often followed by biting and pushing the male away. Both sexes' calls last on average for 1 second, and the interval between calls is on average 3 seconds. Infants are born with their eyes open and fully furred and are able to groom themselves. The mother will carry her infant in her mouth and when she forages for food the mother will park the infant on a branch. Infant sounds are mostly clicks: "k", "tk", "ki", or a rapid "kooih" and can be heard when the infant is left alone or is cold. The mother stays in contact with their infants using high-pitched calls. Infants were found to first use the tails as support during resting at 7–10 days. Young leave their range at the onset of puberty, and find their own territory. Social grooming in this species only occurs between mothers and infants, removing dead skin and parasites by scratching with their toe claws and licking their fur, avoiding their faces. Faces are cleaned by rubbing on branches and it is to reinforce social bonds. Horsfield's tarsier marks its territory with scents from urine and glandular secretions on a substrate while scratching the surface with its hind-limb toe claws.


Conservation status

The rapid loss of habitat due to forest conversion, oil palm plantations, fire and logging is cause for concern. Additionally, the species is also collected for the illegal pet trade and wrongly considered a pest to agricultural crops. It can suffer, directly and indirectly, from the use of agricultural pesticides. Horsfield's tarsier is listed as vulnerable in the 2008 IUCN Red List of Threatened Species, listed in
CITES CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of interna ...
Appendix II, and protected by law in Indonesia and in Malaysia. In February 2007, the governments of
Brunei Brunei ( , ), formally Brunei Darussalam ( ms, Negara Brunei Darussalam, Jawi alphabet, Jawi: , ), is a country located on the north coast of the island of Borneo in Southeast Asia. Apart from its South China Sea coast, it is completely sur ...
,
Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...
, and
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
agreed to protect roughly of tropical forest in the "
Heart of Borneo The Heart of Borneo is a conservation agreement initiated by the World Wide Fund for Nature to protect a 220,000 km² forested region on Borneo island. The agreement was signed by the governments of Brunei, Indonesia and Malaysia in Bali on 1 ...
" region. Environmental group WWF was particularly active in the establishment of the protected area. In the "Heart of Borneo" project,
non-governmental organization A non-governmental organization (NGO) or non-governmental organisation (see spelling differences) is an organization that generally is formed independent from government. They are typically nonprofit entities, and many of them are active in h ...
s (NGOs) have played a role in promoting the critical initiative and in assisting the transboundary nations in its conceptualization, design, and implementation. The transboundary nations are to improve biodiversity conservation in Bornean production forests, and to ensure that such forests are not simply converted to agricultural land-uses such as oil-palm plantations after logging.World Wildlife Fund. (2007). Resolution concerning the ‘Heart of Borneo’. Association for Tropical Biology and Conservation.


References


External links

{{Taxonbar, from1=Q22113538, from2=Q846009
Horsfield's tarsier Horsfield's tarsier (''Cephalopachus bancanus''), also known as the western tarsier, is the only species of tarsier in the genus ''Cephalopachus''. Named for American naturalist Thomas Horsfield, it occurs on Borneo, Sumatra and nearby islands ...
Primates of Indonesia Mammals of Borneo Mammals of Brunei Mammals of Malaysia Vulnerable fauna of Asia
Horsfield's tarsier Horsfield's tarsier (''Cephalopachus bancanus''), also known as the western tarsier, is the only species of tarsier in the genus ''Cephalopachus''. Named for American naturalist Thomas Horsfield, it occurs on Borneo, Sumatra and nearby islands ...
Taxa named by Thomas Horsfield