False gharials are freshwater crocodiles that are found throughout Indonesia (including Kalimantan, eastern Sumatra, western Java, and western Borneo), parts of Malaysia (including Peninsular Malaysia and Sarawak), and Brunei. There have been unconfirmed reports of false gharials in Vietnam and Sulawesi, Indonesia. They are assumed to be extirpated in southern Thailand, where they have not been seen since the 1970s. False gharial populations are isolated and occur in low densities throughout their range. The largest known populations are in Sumatra and Kalimantan, with smaller established populations in Malaysia. The highest density population of false gharials is in Tanjung Puting National Park in Kalimantan.
Biogeographic Regions: oriental (Native )
Tomistoma schlegelii historically occurred over parts of Indonesia (Müller 1838, Weber 1890, de Rooij 1915), Malaysia (Boulenger 1896, Annandale and Robinson 1904, Smith 1930) and possibly Thailand (Taylor 1970). Unconfirmed reports are from Sabah (Borneo) and Viet Nam but are vague and inconclusive (Stuebing et al. 2006). The current distribution of T. schlegelii extends over lowland regions of eastern Sumatra, Kalimantan and western Java (Indonesia), and Sarawak and Peninsular Malaysia (Malaysia), within five degrees north and south of the equator (Stuebing et al. 2006). The species was recently confirmed to occur in Brunei Darussalam. The largest extant populations are in Kalimantan and Sumatra. Most documented populations are diminished and fragmented. Previous reviews of global distribution are by Sebastian (1994) and Stuebing et al. (2006). Summaries of national distribution are as follows.
Brunei Darussalam: Few crocodile surveys conducted to date (e.g. Das and Charles 2000, Cox 2006) and possibly none targeting inland swamp forests, where T. schlegelii are most likely to occur. A crocodile photographed by an expatriate resident in 2005 at Tutong River was confirmed by RBS (from examination of the photograph) to be a T. schlegelii (Stuebing et al. 2006). There is no reason to suggest this was a released individual and it is the first confirmed national record.
Java – status unclear. Koningsberger (1913: 376) noted (in translation) ‘whether, apart from C. porosus, T. schlegelii also occurs in Java, is a question that cannot be answered with certainty..’. Meer Mohr (1921) noted (in translation) ‘according to Strauch, T. schlegelii occurs in Java…the only specimen from Java is in the museum in Stuttgart [Germany]...the origin of this specimen is uncertain...further work is required to clarify the status of T. schlegelii in Java..’. More recently, unconfirmed local reports of T. schlegelii have been obtained from one site, Ujung Kulon National Park (Auliya 2002). The most detailed account of crocodiles for this park is by Hoogerwerf (1970), who does not mention the species. Given the small size of the park and modified nature of surrounding lands, any populations are presumably small.
Kalimantan – confirmed records are from Tanjung Puting National Park (Central Kalimantan Province; e.g. Galdikas and Yeager 1984, Galdikas 1985, Simpson 2004, Auliya et al. 2006), the Mahakam and Belayan river systems and Mesangat Lake (East Kalimantan Province; Endert 1927, Meijard and Sozer 1996, Ross et al. 1998, Staniewicz 2011) and upper Kapuas river area, Danau Sentarum and Gunung Palung National Parks (West Kalimantan Province; Bezuijen et al. 2004 and references therein; Simpson and Mediyansyah 2009); no conﬁrmed wild records from South Kalimantan Province. The species is likely to persist in many other locations in Kalimantan, and the limited number of confirmed localities probably reflects low sampling effort.
Sumatra – all known records are from eastern Sumatra, east of the Barisan Mountain Ranges (Bezuijen et al. 1998). Scattered populations persist from North Sumatra to South Sumatra Provinces, with an isolated population in Way Kambas National Park (Lampung Province). The range of T. schlegelii in Sumatra has declined by at least 30% since the 1950s due to hunting and habitat loss (Bezuijen et al. 1998).
Malaysia: Small populations persist in Peninsular Malaysia and presumably Sarawak (Malaysian Borneo; historical localities include Batang Lupar, Simunjan, and Ensengai). Peninsular Malaysia – confirmed localities are in the Perak and Pahang Rivers, Selangor swamp and Tesak Bera Ramsar Site, all in the western portion of the peninsula (Stuebing et al. 2004, 2006; Bezuijen et al. 2012). Hatchling T. schlegelii observed at a wildlife trader’s facility in 1997 were reported to be wild-caught, suggesting breeding persists in the peninsula (Bezuijen et al. 2012). Remnant populations are almost certainly under severe threat given extensive and continuing loss of lowland swamps and high human densities of this region (authors pers. obs.). Sarawak – status unclear; reported (but largely unconfirmed) from Kuching, Bintulu and Miri Divisions. Sabah – unconfirmed local reports; no other information available (Stuebing et al. 2006).
Thailand: Status unclear. Reported to have occurred (e.g. Smith 1916, Taylor 1970) but records vague and inconclusive. No reports since at least the 1970s; previous authors have postulated the species may be extirpated (Humphrey and Bain 1990, Ratanakorn 1994) or that historical records may have referred to localities in northern Peninsular Malaysia (Stuebing et al. 2006).
Viet Nam: Status unclear. A wild crocodile captured in 1967 was reported to be this species (Mucelli 2005). Given the severe threats facing two confirmed crocodile species in Viet Nam, Crocodylus siamensis and C. porosus, it seems likely that even if T. schlegelii was historically present, it has been extirpated.
Distribution: Indonesia (Sumatra, Borneo, Kalimantan, Java, Sulawesi), Malaysia (Malay Peninsula), S Thailand, Vietnam
Type locality: Karau river and Lake Lamoeda on river Doeson, Southern Borneo.
False gharials are large crocodilians characterized by a long, narrow snout snout filled with 76-84 sharp pointed teeth, similar to that of gharials (Gavialis gangeticus), from which false gharials get their common name. False gharials have a streamlined body and muscular tail, eyes and nostrils on top of the head, and a palatal valve that prevents water from entering the throat while underwater. They are known to grow to 4-5 m in length and may grow even larger. There are records of captive adults weighing from 93-201 kg. Both adults and juveniles have dark, sometimes chocolate brown coloration, with black banding on the tail and body and dark patches on the jaws. The belly is cream-colored or white. Males are longer and heavier than females.
Range mass: 93 to 210 kg.
Range length: 4 to 5 m.
Sexual Dimorphism: male larger
Other Physical Features: ectothermic ; bilateral symmetry
False gharials are found in a variety of habitats throughout their range, including lowland freshwater swamp forests, flooded forests, peat swamps, lakes, and blackwater streams and rivers. They are also found on the fringes of rainforests near slow-moving rivers. Their preferred habitats are peat swamp areas with low elevation and acidic, slow-moving muddy water; they are also found in secondary forest habitat, characterized by more defined river channels and banks, higher pH and elevation, and a lack of peat mounds. This species needs terrestrial areas for basking and nesting.
Range elevation: 0 to 20 m.
Range depth: 0.30 to 1.10 m.
Habitat Regions: tropical ; terrestrial ; freshwater
Terrestrial Biomes: forest ; rainforest
Aquatic Biomes: lakes and ponds; rivers and streams; temporary pools
Wetlands: marsh ; swamp ; bog
Other Habitat Features: riparian
Habitat and Ecology
Tomistoma schlegelii is a freshwater, mound-nesting species. It is among the largest of the extant crocodilians, with males attaining lengths up to 5+ m (Bezuijen et al. 1998, 2004; authors pers. obs.). It is restricted primarily to lowland swamps, lakes and rivers. Most records are from peat swamp and freshwater swamp forest (Stuebing et al. 2006), which historically encompassed most of the lowlands of Borneo, eastern Sumatra, and Peninsular Malaysia.
The ecology of T. schlegelii, including nesting, size and age of sexual maturity, diet, and population demography, remains poorly known. Fewer than 20 wild nests have been documented. Most nests in Sumatra and Kalimantan have been located at the base of large trees in mature peat swamp forest, along remote tributaries (Endert 1927, Bezuijen et al. 2001, Staniewicz 2011). In Sarawak, a nest was located in degraded forest at the edge of cultivated land (Lading and Stuebing 1997). Nests have been reported from floating vegetation mats (Ross et al. 1998). Nesting occurs in the dry season and small clutches (13-41 eggs) are laid (Endert 1927, Bezuijen et al. 2001). Hatchlings emerge in the late dry season / early wet season after an estimated 70-80 days incubation (Bezuijen et al. 1997). Tomistoma schlegelii produces the largest eggs of all living crocodilians (Bezuijen et al. 1998). Sexual maturity in females appears to be attained at around 2.5-3 m total length and 20 years age (Bezuijen et al. 1998, Shwedick 2006, Brazaitis and Abene 2008; B. Ziegler [Miami Metro Zoo, USA] pers. comm. to J.P. Ross 1995; U. Youngprapakorn [Utairatch Crocodile Farm & Zoo, Thailand]) pers. comm. to authors 2008), a relatively large size and late age compared with other crocodilians.
Müller (1838) stated the diet of T. schlegelii comprised fish, monitor lizards (Varanus), waterbirds and mammals. Predation of monkeys by T. schlegelii has been observed (Galdikas and Yeager 1984, Galdikas 1985, Yeager 1991). Stomach contents of juvenile wild T. schleglii included shrimp (Bezuijen et al. 1998) and other invertebrates (Staniewicz and Behler 2010).
Other scientific studies of T. schlegelii have included assessment of its taxonomic status (see Taxonomic Notes), anatomy and skin qualities (e.g. Boulenger 1896, King and Brazaitis 1971, Brazaitis 1973, Fuchs 2006), potential impacts of climate change (Bickford et al. 2010), conservation effectiveness of protected area networks (Rödder et al. 2010), and captive breeding and management (see Conservation Measures).
False gharials are opportunistic carnivores. They have been reported to grab monkeys (Crab-eating macaques (Macaca fascicularis) and other Macaca sp.) from river banks, submerging and drowning their prey or beating it against the bank. Other prey items include wild pigs, mouse deer, dogs, otters, fish, birds, turtles, snakes, monitor lizards, and aquatic and terrestrial invertebrates.
Animal Foods: birds; mammals; reptiles; fish; insects; terrestrial non-insect arthropods; aquatic crustaceans
Primary Diet: carnivore (Eats terrestrial vertebrates, Piscivore )
The role of false gharials in their ecosystem is not completely understood due to a lack of study in the wild. They are large predators, preying on a variety of animals and keeping their populations in check. Their distribution overlaps with that of Siamese crocodiles (Crocodylus siamensis) and saltwater crocodiles (Crocodylus porosus), and it is not known how much competition for resources there is amongst these species.
- Nematodes (Phylum Nematoda)
Adult false gharials are usually safe from predators due to their large size. Eggs and hatchlings preyed upon by Wild pigs (Sus scrofa) and larger reptiles, such as monitor lizards. Eggs may be collected and consumed by humans as well. In captivity, hatchlings have been killed by termites and ants before emerging from the nest mound.
- Wild pigs (Sus scrofa)
- Monitor lizards (Varanus sp.)
Life History and Behavior
Communication among false gharials has not been observed in the wild. From observed mating behaviors, it can be assumed that they communicate visually, tactilely and through olfaction. Although most crocodilians use a variety of calls to communicate with their own species and to other animals, these have not been recorded for false gharials and, in fact, their mating has been observed to be silent, rather than accompanied by calls. All crocodilians possess integumentary sense organs located in the skin and covering much of the animal’s body including the body, tail, cloaca and inner surfaces of the legs, as well as on the head and jaws. These are likely used to detect changes in pressure caused by touch or the movement of prey in water; this sense is likely used for hunting in murky water.
Communication Channels: visual ; tactile ; acoustic
Other Communication Modes: vibrations
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
False gharial eggs have a soft inner membrane and harder, calcified shell. Crocodilian sex is determined by temperature rather than genetics. Incubation lasts approximately 90 days and young resemble small adults upon hatching. Hatchlings are equipped with an “egg tooth”, a pointed structure on the end of the snout that allows the hatchling to slice through the egg shell; this recedes a few weeks after hatching.
Development - Life Cycle: temperature sex determination; indeterminate growth
False gharials are long-lived animals with an estimated lifespan in the wild of 60 to 80 years, similar to that of other crocodilians. Reports show that captive specimens have a shorter lifespan.
Status: wild: 60 to 80 years.
Lifespan, longevity, and ageing
Very little is known about the natural mating behaviors of false gharials; most details are from captive breeding programs, with a few acocunts from the wild. Courtship behavior and nesting appear to take place during the rainy season in both cases. Males approach females in the water, swimming around them. In some cases, this is accompanied by both animals hitting each other with their tails, in others copulation proceeds immediately. The male mounts the female, wrapping his tail around and under hers. Copulation occurrs once a day for several days to a week, and is accompanied by a strong odor. One captive breeding program in Malaysia had success housing a group of 3 males and 1 female. The female chose the largest male and appeared to stay near him during the courting period. When 2 females were kept in the same enclosure with the males, no mating occurred and it is theorized that females living in close proximity may suppress breeding in one another.
Mating System: monogamous
False gharials are mound-nesting crocodilians that lay very large eggs (records up to 9.5 cm long and 6.2 cm wide), with a total mass approximately double that of any other species (eggs may weigh up to 155 gm each). Mounds are usually constructed on land at the shady base of a tree near water, using sand and vegetation including peat, twigs, tree seeds, and dried leaves. Females have been observed beginning nest building a month or more after copulation and laying a clutch of 20-60 eggs 1-2 weeks after beginning to nest. After eggs are laid, more vegetation is added to the top of the nest by the female. Mounds typically measure 45-60 cm high and 90-110 cm in diameter. Eggs are laid just above ground level and the temperature within the nest fluctuates depending on the environment and rainfall (records in captivity of 26°C-32°C). Eggs hatch after 90-100 days. Captive breeding initiatives have shown that abundant vegetation improves the chances of breeding because it provides more cover and nesting material for the female. Both sexes reach sexual maturity at around 20 years of age (females measuring 2.5-3 m in length).
Breeding interval: False gharials breed twice yearly.
Breeding season: False gharial breeding occurs during the wet seasons: November-February and April-June.
Range number of offspring: 20 to 60.
Range gestation period: 90 to 115 days.
Average age at sexual or reproductive maturity (female): 20 years.
Average age at sexual or reproductive maturity (male): 20 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; oviparous
Males exhibit no parental investment beyond fertilization. Females have occasionally been observed sitting on top of nest mounds or defending them by stomping the ground, but more often flee the nest if approached. There is evidence that females may help to excavate nests before or during hatching. but they have not been observed helping hatchlings to the water as some crocodilians do. No parental investment beyond this has been observed.
Parental Investment: female parental care ; pre-fertilization (Provisioning); pre-hatching/birth (Protecting: Female)
Molecular Biology and Genetics
Barcode data: Tomistoma schlegelii
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Tomistoma schlegelii
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
Since the 1890s, sightings and captures of wild specimens have been rare, and it has become increasingly difficult for researchers to locate any individuals for study. Populations, which tend to be very small, are restricted to small patches of swamp or forest. There has been a significant decline in the density of populations since the 1940s. In 2000 this species was assessed by the Crocodile Specialist Group and reported as endangered, with an estimate of less than 2,500 individuals remaining in the wild. More surveys must be conducted to determine the number of individuals remaining before a conservation plan can be developed. The Crocodile Specialist Group Tomistoma Task Force (CSG-TTF) has conducted fundraising for field research and international awareness, and produced reports on conservation priorities and captive breeding. False gharials are threatened by many factors including habitat loss through forest fires, drainage of wetlands, logging, agriculture development, slash and burn agriculture, and dam building. These activities have reduced this species' range in Sumatra by 30-40%. False gharials are now legally protected throughout their entire range, but enforcement of laws has been insufficient to maintain stable populations and breeding habitat. Trade of the species is also prohibited by law, but not well enforced.
US Federal List: endangered; no special status
CITES: appendix i
State of Michigan List: no special status
IUCN Red List Assessment
Red List Category
Red List Criteria
This species qualifies as Vulnerable as global populations have been reduced, almost certainly by over 30% in the past 75 years / three generations (assuming a generation time of 25 years), principally due to continuing loss and fragmentation of swamp forest over the past three to four decades. Tomistoma schlegelii persists over a wide range (confirmed localities in Borneo, Sumatra and Peninsular Malaysia), but many documented populations are small, fragmented, and under threat from habitat loss. The largest remaining–and most secure–subpopulations may be in East and Central Kalimantan, which support thousands of square kilometres of degraded but largely undeveloped wetlands. Given this, it appears unlikely that <2,500 mature individuals remain globally (the IUCN definition for Endangered), as a relatively small number of sites with small subpopulations (e.g. 50 sites each with 50 individuals or 100 sites each with 25 individuals) is required to meet this criterion. The previous IUCN Red List status (vers. 2.3) for this species was Endangered (Crocodile Specialist Group 2000): the current downgrade in global status to Vulnerable does not imply an increase in the global population/range or a reduction in threats, but a more accurate assessment than was previously possible. Nonetheless, it remains possible that T. schlegelii qualifies as globally Endangered, due to ongoing habitat loss and degradation. At the national and/or site level, this is almost certainly the case for some range states, particularly Malaysia. T. schlegelii was accorded the IUCN Red List status of ‘Endangered’ in 1998 at an expert workshop during the 14th Working Meeting of the IUCN SSC Crocodile Specialist Group. Since that time, new survey data for sites in Kalimantan, Sumatra and Peninsular Malaysia have become available, enabling a more accurate assessment of global threat status. The global status of T. schlegelii is reassessed to be Vulnerable. This is largely based on inferences about habitat loss, rather than documented changes in abundance, because little quantitative data is available for the species. Most surveys have recorded low densities of individuals. Documented examples of population decline include a site in Sumatra, where an increase in logging and burning coincided with a decline in T. schlegelii densities over a seven-year period (Bezuijen et al. 2002), and a park in Kalimantan, where T. schlegelii densities were higher in intact swamp forest than nearby degraded areas (Simpson 2004, Auliya et al. 2006). The species is cryptic and difficult to detect, and rapid assessments may under-record or fail to detect the species, leading to inaccurate conclusions of status. In some parts of Kalimantan, T. schlegelii appears to maintain reasonable levels of abundance even after many cycles of logging and burning in peat/freshwater swamps; in other areas, surveys and local information clearly indicate the species has declined. The principal threat to T. schlegelii is severe and continuing loss of swamp forest, mainly due to logging, fire, drainage, and plantation development. Other threats include entanglement in fishing gear, low-level opportunistic removal of T. schlegelii from the wild, usually by residents and crocodile farmers, who keep juveniles or eggs as items of curiosity, and potentially climate change, which may result in large-scale modification of nesting habitats. Many river systems remain unsurveyed for T. schlegelii and it remains one of the least known crocodilians.
Reasons for Change A downgrade in IUCN Red List status from Endangered to Vulnerable is warranted because surveys indicate the species persists over a wide global range. It has clearly declined in many areas and ongoing habitat loss suggests these declines are continuing.
- 1996Data Deficient
- 1996Data Deficient(Baillie and Groombridge 1996)
- 1994Endangered(Groombridge 1994)
- 1990Endangered(IUCN 1990)
- 1988Endangered(IUCN Conservation Monitoring Centre 1988)
- 1986Endangered(IUCN Conservation Monitoring Centre 1986)
Date Listed: 06/14/1976
Lead Region: Foreign (Region 10)
Where Listed: Entire
Population location: Entire
Listing status: E
For most current information and documents related to the conservation status and management of Tomistoma schlegelii , see its USFWS Species Profile
No global or national population estimates are available for T. schlegelii. Spotlight densities are the only indices of abundance available for this species and have been documented in relatively few sites. Extrapolation of these densities to larger areas may be unreliable, because densities along rivers or creeks (where most surveys have occurred) may be highly different from swamp forest habitats. This issue is confounded by varying detectability (greater along waterways than within swamp forest). The highest recorded density of T. schlegelii is 1.4-2.6 individuals/km, along a well-protected short (<4 km) river section at the headquarters of Tanjung Puting National Park, Central Kalimantan Province (Simpson 2004, Auliya et al. 2006). This density is apparently atypical for the park: in areas of the park further from the headquarters, habitats are more disturbed and T. schlegelii densities are much lower (Auliya et al. 2006). In Danau Sentarum National Park (West Kalimantan Province), spotlight densities at a site ranged from 0.21 individuals/km in 1994 (Frazier 1994) to 0.08 individuals/km in 2004 (Bezuijen et al. 2004), and 0.02-0.07 individuals/km at other sites (Bezuijen et al. 2004, Simpson and Mediyansyah 2009). At Mesangat Lake (East Kalimantan Province), T. schlegelii is locally abundant; in 2012, densities ranged from 0.2-1.6 individuals/km in flooded forest and open water habitats (Staniewicz 2011). In Sumatra, the highest recorded spotlight densities of T. schlegelii are 0.18 and 0.26 individuals/km, at two sites in South Sumatra and Jambi Provinces respectively (Bezuijen et al. 2002).
Tomistoma schlegelii is a cryptic species and swamp forest habitats are difficult to access: many surveys may have under-recorded or not detected its presence. Compared with spotlight densities for some other crocodilians, which may reach densities of tens or hundreds of individuals per kilometre, all recorded densities of T. schlegelii are low. Repeat spotlight counts at two sites in Sumatra indicate that densities declined over a seven-year period, which coincided with intensive logging and burning in these sites (Bezuijen et al. 2002).
Few other methods to estimate abundance have been applied to T. schlegelii. A mark-recapture study was conducted from 2010-2011 at Mesangat Lake (East Kalimantan Province, Indonesia) but few individuals have been recaptured (Staniewicz 2011). Nest census methods have not been applied to T. schlegelii because nests are located in swamp forest and are highly cryptic.
There is presently insufficient data to estimate the global population of T. schlegelii. Criterion C of the IUCN Red List defines the difference between ‘Endangered’ and ‘Vulnerable’ as the global number of mature individuals to be fewer than 2,500 or 10,000 respectively (IUCN 2001). Whether or not there are fewer than 10,000 mature individuals is unknown. Conversely, there is higher confidence in concluding there are more than 2,500 mature individuals. To achieve a minimum global number of 2,500 mature individuals, a relatively small number of sites with small subpopulations is required e.g. 50 sites each with 50 individuals or 100 sites each with 25 individuals. Given the large extent of swamp forest habitat remaining across the global range of the species (over 13 million hectares of peat swamp in Sumatra, Borneo and Peninsular Malaysia; Yoshino et al. 2010), this seems reasonable.
This generalized conclusion of global status clearly does not reflect trends for all individual range states. East and Central Kalimantan Provinces, which support large tracts of degraded swamp forest, may support the largest remaining populations of T. schlegelii, although surveys are required to confirm this. In at least one site in East Kalimantan Province, Mesangat, preliminary data indicates T. schlegelii persist in relatively degraded swamp forest habitats (Staniewicz 2011). If this is the case elsewhere in East and Central Kalimantan Provinces, the remaining numbers of mature individuals in these provinces may be relatively high. In contrast, survey data from sites in West Kalimantan Province and Sumatra suggest that logging, burning and other human pressures have resulted in reduced T. schlegelii densities. In Peninsular Malaysia, severe and continuing clearance of remnant swamp forest, high human populations, and high levels of economic development, suggest that localized declines or even extirpation may be occurring (see Threats). In Brunei, any remnant breeding populations are probably small, given the small size of the nation and limited extent of swamp forest habitat.
Severe and continuing loss of swamp forest habitat throughout the global range of T. schlegelii is the key threat to most wild populations. Loss and fragmentation of swamp forest has been occurring for over three decades throughout Southeast Asia due to large-scale commercial and illegal logging, plantation development (especially the establishment of paper pulp mills and palm oil plantations), forest fires, and deliberate swamp drainage through construction of channels and dykes. Large areas of swamp forest in East, Central and West Kalimantan were destroyed or severely degraded by the El Niño-induced drought of 1997 and 1998 (Stibig et al. 2007). The expansion of oil palm plantations is currently the main driver of loss of swamp forest in Sumatra and Borneo (Stibig et al. 2007). Based on satellite imagery from 2000, almost 45% (>one million hectares) of peat swamp in Peninsular Malaysia and Thailand has been converted to various land uses, and over a million hectares has been converted in Borneo and Sumatra (Yoshino et al. 2010). Across the global range of T. schlegelii, Borneo retains the largest area of peat swamp under natural cover (70-90%), but which is of varying quality and much is degraded (Yoshino et al. 2010). At least in Sumatra, a significant threat appears to be predation of T. schlegelii eggs by the introduced wild pig Sus scrofa; four of seven T. schlegelii nests recorded along one river were predated by this species (Bezuijen et al. 1997). A smaller but potentially significant threat is opportunistic removal of T. schlegelii and eggs from the wild, usually by residents and crocodile farmers (see Use and Trade). Commercial hunting of T. schlegelii occurred in some regions from the 1950s-1970s and probably contributed to the decline of the species, but no longer occurs. Individuals sometimes drown in fishing nets. In areas with depressed and threatened populations, the continuing low-level removal of mature individuals (e.g. from drowning or capture in fishing gear) may cause disproportionately large impacts; this may be the case along some rivers in southern Sumatra (Bezuijen et al. 2001). Fishing appears to be less of a threat in East Kalimantan (Indonesia) and possibly Sarawak (Malaysia), where fishermen apparently release T. schlegelii caught in fishing gear due to local beliefs that harming the species will bring bad luck or illness (RBS pers. obs.).
Since the 1990s, rapid status assessments for T. schlegelii have been conducted in East and Central Kalimantan (Frazier 1994, Muin and Ramono 1994, Ross et al. 1998, Staniewicz 2011), Central Kalimantan (Auliya et al. 2006, Bonke 2006, Simpson 2004), West Kalimantan (Auliya 2000, Bezuijen et al. 2004, Simpson and Mediyansyah 2009), Sumatra (Bezuijen et al. 1998, 2002), and Peninsular Malaysia (Simpson et al. 1998). Reviews of national or global distribution (Sebastian 1994; Stuebing et al. 2004, 2006) have been prepared. The first dedicated research project on the species was conducted from 1995-1997 and resulted in a status assessment for Sumatra as well as new data on the ecology of T. schlegelii (Bezuijen et al. 1998, 2001). In 2001-2002, largely through the voluntary efforts of MRB and G.J.W. Webb, repeat-surveys were conducted at two sites in Sumatra, and the ﬁrst Indonesian workshop on T. schlegelii was held (Bezuijen et al. 2001, 2002). Sumatran agencies and NGOs subsequently conducted additional surveys which resulted in the discovery of a new nesting site and protection of swamp forest (Bezuijen 2004). These various efforts have resulted in new information on the distribution, status, breeding biology and of ecology of T. schlegelii.
In 2003, the IUCN Crocodile Specialist Group (CSG) formed the Tomistoma Task Force (TTF), a group of CSG members who coordinate the CSG’s efforts for T. schlegelii conservation. TTF activities comprise fundraising for ﬁeld research, international awareness-raising, and hosting of a TTF website. Fund-raising events have been held in North America and Europe, largely due to the voluntary efforts of BS, R. Sommerlad and other CSG members. Two T. schlegelii student projects have been co-funded and are the first detailed autecological studies of the species. TTF reports have been prepared on global conservation priorities (Bezuijen et al. 2003) and husbandry standards for captive breeding of T. schlegelii (Shwedick and Sommerlad 2000, Shwedick 2006). In 2008, a TTF workshop was held and a re-assessment of global conservation priorities was undertaken.
Other initiatives include the following. In 2009, a foundation, Yayasan Ulin, was established in East Kalimantan by RBS to promote wetland and crocodile conservation. This has resulted in co-management agreements with a plantation company to conserve crocodile habitats, support for two international internships studying T. schlegelii and Crocodylus siamensis, and the identification of wetland sites important for biodiversity conservation (Yayasan Ulin 2012). In West Kalimantan, the People, Resources, and Conservation Foundation (PRCF) is planning T. schlegelii conservation activities in Danau Sentarum National Park, to build on surveys in 2004 (Bezuijen et al. 2004). In the nearby Lake Siawan-Belida area, Fauna & Flora International are developing an ecosystem restoration project to manage the swamp forest, including T. schlegelii (Simpson and Mediyansyah 2009). In Sumatra, the non-government organization Wahana Bumi Hijau is implementing a project ‘Protection of the Senyulong crocodile habitat in the Merang-Kepayang peat swamp forest’ [south-east Sumatra]. In 2009 the project received technical assistance from IUCN Netherlands and Mabuwaya Foundation (Philippines) (Weerd and Balbas 2009). In nearby Berbak National Park, the Zoological Society of London is developing the ‘Berbak Carbon Initiative’ to develop carbon markets to protect swamp forest (Suratno and Maddox 2010), which may indirectly benefit local T. schlegelii populations.
In 2010 the CSG Status Survey and Conservation Action Plan was updated, including an update on status and conservation priorities for T. schlegelii (Bezuijen et al. 2010).
Despite these efforts, T. schlegelii conservation is constrained by a lack of long-term research and conservation programs. Virtually all initiatives are conducted with limited funds, often on a voluntary basis, and by virtue of their brief duration have not been sufﬁcient to develop expanded conservation programs. There is a need to assign and fund full-time persons who will coordinate T. schlegelii conservation efforts, including the preparation of funding proposals and lobbying for integration of T. schlegelii into the workplans of provincial governments and international projects.
Tomistoma schlegelii has no commercial skin value, precluding conservation efforts based on ranching as conducted for some other crocodilians.
Relevance to Humans and Ecosystems
False gharials are not considered to be a threat to humans. There has been only one documented case of an attack on a human, and one documented attack on a cow in eastern Kalimantan.
Negative Impacts: injures humans (bites or stings)
False gharials were once hunted for their skins, but their skins are not currently considered commercially valuable. In the Mesangat area, their eggs are collected for use in traditional medicine. There is a good deal of research being done to learn more about the roles these animals play in their environments, as well as to determine whether they should be placed in the family Crocodylidae or the family Gavialidae.
Positive Impacts: body parts are source of valuable material; source of medicine or drug ; research and education
The false gharial (Tomistoma schlegelii), also known as the Malayan gharial and Sunda gharial, is a freshwater crocodilian with a very thin and elongated snout. It is listed as "Vulnerable" by the IUCN, as the population is estimated at comprising less than 2,500 mature individuals.
The false gharial is dark reddish-brown above with dark brown or black spots and cross-bands on the back and tail. Ventrals are grayish-white, with some lateral dark mottling. Juveniles are mottled with black on the sides of the jaws, body, and tail. The smooth and unornamented snout is extremely long and slender, parallel sided, with a length of 3.0 to 3.5 times the width at the base. All teeth are long and needle-like, interlocking on the insides of the jaws, and are individually socketed. The dorsal scales are broad at midbody and extend onto the sides of the body. The digits are webbed at the base. Integumentary sensory organs are present on the head and body scalation. Scales behind the head are frequently a slightly enlarged single pair. Some individuals bear a number of adjoining small keeled scales. Scalation is divided medially by soft granular skin. Three transverse rows of two enlarged nuchal scales are continuous with the dorsal scales, which consist of 22 transverse rows of six to eight scales, are broad at midbody and extend onto the sides of the body. Nuchal and dorsal rows equals a total of 22 to 23 rows. It has 18 double-crested caudal whorls and 17 single-crested caudal whorls. The flanks have one or two longitudinal rows of six to eight very enlarged scales on each side.
The snout is even slimmer than the snout of the slender-snouted crocodile and comparably as slender as that of the gharial. The false gharial is a large crocodilian, measuring only slightly smaller than the gharial. Three mature males kept in captivity measured 3.6 to 3.9 m (12 to 13 ft) and weighed 190 to 210 kg (420 to 460 lb), while a female measured 3.27 m (10.7 ft) and weighed 93 kg (205 lb). In some cases, males can reportedly grow to as much as 5 m (16 ft) in length. Adult males weigh 150 to 250 kg (330 to 550 lb), while females are about 3.2 m (10 ft) long and weigh an average of 90 kg (200 lb).
Distribution and habitat
False gharials are native to Peninsular Malaysia, Sarawak, Sumatra, and Borneo, but were extirpated in Thailand. It is unclear if they remain in Java. Apart from rivers, they inhabit swamps and lakes. In the 1990s, information and sightings were available from 39 localities in 10 different river drainages, along with the remote river systems of Borneo.
Prior to the 1950s, Tomistoma occurred in freshwater ecosystems along the entire length of Sumatra east of the Barisan Mountains. The current distribution in eastern Sumatra has been reduced by 30-40% due to hunting, logging, fires, and agriculture.
Ecology and behaviour
Until recently, very little has been known about the diet or behavior of the false gharial in the wild; as a result of research by biologists details are slowly being revealed. In the past, the false gharial was thought to have a diet similar to its relative the gharial (only fish and very small vertebrates), but new evidence and occurrences have proven, despite the false gharial's narrow snout, it has a generalist diet. In addition to fish and smaller water animals, mature adults will prey on larger vertebrates, including proboscis monkeys, long-tailed macaques, deer, water birds, and reptiles.
At the end of 2008, a 4-m female false gharial attacked and ate a fisherman in central Kalimantan; his remains were found in the gharial's stomach. This was the first verified fatal human attack by a false gharial, although at least one other is suspected.
False gharials are mound-nesters. Females lay small clutches of 13 to 35 eggs per nest, and appear to produce the largest eggs of extant crocodilians. Sexual maturity in females appears to be attained around 2.5 to 3 m (8.2 to 9.8 ft), which is large compared to other crocodilians.
It is not known when they breed in the wild or when the nesting season is. Once the eggs are laid, and construction of the mound is completed, the female abandons her nest. Unlike most other crocodilians, the young receive no parental care and are at risk of being eaten by predators, such as mongooses, tigers, leopards, civets, and wild dogs. The young hatch after 90 days and are left to fend for themselves.
The false gharial is threatened with extinction throughout most of its range due to the drainage of its freshwater swamplands and clearance of surrounding rainforests. The species is also hunted frequently for its skin and meat, and the eggs are often harvested for human consumption.
Steps have been taken by the Malaysian and Indonesian governments to prevent its extinction in the wild. There are reports of some populations rebounding in Indonesia, yet with this slight recovery, mostly irrational fears of attacks have surfaced amongst the local human population.
Yayasan Ulin (The Ironwood Foundation) is currently attempting to manage a wetland area in East Kalimantan which is known to contain the gharials.
From a morphological standpoint, it was originally placed within the family Crocodylidae, but numerous molecular studies have consistently indicated that it is the nearest relative (the sister taxon) of the gharial. Along with close fossil relatives, such as Maroccosuchus, it is thus increasingly classed in the family Gavialidae.
- Bezuijen, M.R., Shwedick, B., Simpson, B.K., Staniewicz, A. & Stuebing, R. (2014). "Tomistoma schlegelii". IUCN Red List of Threatened Species. Version 2014.3. International Union for Conservation of Nature.
- Willis, R. E.; McAliley, L. R.; Neeley, E. D.; Densmore Ld, L. D. (June 2007). "Evidence for placing the false gharial (Tomistoma schlegelii) into the family Gavialidae: Inferences from nuclear gene sequences". Molecular Phylogenetics and Evolution 43 (3): 787–794. doi:10.1016/j.ympev.2007.02.005. PMID 17433721.
- Brazaitis, P. (2001) A Guide to the Identification of the Living Species of Crocodilians. Science Resource Center, Wildlife Conservation Society
- Bezuijen, M.R., Webb, G.J.W., Hartoyo, P., Samedi, Ramono, W.S., Manolis, S.C. (1998) The False Gharial (Tomistoma schlegelii) in Sumatra. In: Crocodiles. Proceedings of the 14th Working Meeting of the Crocodile Specialist Group, IUCN. The World Conservation Union, Gland, Switzerland and Cambridge, UK. Pp. 10–31.
- Rachmawan, D., Brend, S. (2009).Human-Tomistoma interactions in central Kalimantan, Indonesian Borneo Crocodile Specialist Group Newsletter January 2009 – March 2009. Volume 28 No. 1: 9–11.
- "Molecular Systematics of the Order Crocodilia".
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