Bandage monitor

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Bandage monitor
Binding monitor (Varanus salvator), probably V. s. macromaculatus

Binding monitor ( Varanus salvator ), probably V. s. macromaculatus

Systematics
without rank: Toxicofera
without rank: Sneaky (Anguimorpha)
Family : Varanidae
Genre : Monitor lizards ( varanus )
Subgenus : Soterosaurus
Type : Bandage monitor
Scientific name
Varanus salvator
( Laurenti , 1768)

The banded monitor monitor ( Varanus salvator ) is a type of scale crawfish (Squamata) from the genus of monitor monitors ( Varanus ). Black tie monitor lizards are large, dark colored lizards with a light belly and eye spots on the back. Bindweed monitor grows very large and can reach lengths of up to 3 m. The very large distribution area of ​​the species in Southeast Asia extends from the rear Indian peninsula to the south over large parts of Indonesia to Sulawesi . There, black monitor lizards inhabit rivers in rainforests and mangroves , where the strongly water-bound and well-swimming monitor lizards prey on various prey, from insects to fish and reptiles to small mammals and birds. Like all monitor lizards, they are diurnal solitary animals, are opportunistic in terms of habitat and prey and are very adaptable.

The species V. salvator used to represent a whole complex of closely related species, today five subspecies are differentiated within V. salvator and numerous former subspecies are separated as five separate species. Most populations of Southeast Asian black monitors are hunted for their leather and meat, but the lizards seem to be able to withstand the pursuit for the most part. Therefore, according to the IUCN , the sea monitor is considered safe.

features

Varanus salvator in Sri Lanka

The white monitor monitor is a very large monitor, which reaches total lengths of over 2 m when fully grown. In very rare cases lengths of up to 3 m with a weight of 15 kg are achieved; the largest band monitor to date is said to have been 3.21 m long. Males grow larger and heavier than females and are more massive. In 61 animals measured in West Kalimantan , the total length ranged from 58 to 226.5 cm (section 143 cm). The tail length was on average 1.66 times the head-trunk length ; the average weight was 4.12 kg.

The white monitor monitor is built quite elongated, the head is more than twice as long as it is wide. The muzzle is long and rounded at the front, the eardrum is large. The nostrils are round to oval and are quite close to the tip of the snout. The tail has a double keel on the upper edge and is flattened laterally as a rudder tail. The limbs are of normal length for monitor lizards and have strong, curved claws. The blind monitor's teeth are sawed.

There is a large variety of drawings even within individual subspecies of the banded monitor monitor, so that a general description of the coloration is hardly possible. Typical colored specimens of all subspecies have a dark brown to black head with indistinct ribbon markings on the snout and a dark neck, which often shows lighter colored spots. The back is also darkly colored and typically has several rows of light spots or eye spots, often small, light spots in between. The abdomen is brightly colored and has black band markings that extend across the longitudinal axis of the body from the sides of the body to the middle of the abdomen. The tail is darkly colored and can be drawn both with light points and with continuous light transverse bands. Even today, new color variants are described, which may represent new subspecies; in addition, there are numerous morphs within known subspecies, including blacklings ( melanism ).

distribution and habitat

Distribution of the blind monitor (Koch et al. 2007, Koch & Böhme 2010)
yellow: V. s. salvator , green: V. s. macromaculatus , blue: V. s. bivittatus , red: V. s. andamanensis , brown: V. s. ziegleri , gray: populations not yet delimited as a subspecies on Sulawesi

The common monitor monitor is the most widespread of all monitor species and inhabits large parts of Southeast Asia. Its reserves will in the west from northeastern India and Sri Lanka over Bangladesh and Myanmar , as well as in the Bay of Bengal offshore Andaman and Nicobar Islands . Further to the east, its distribution extends on the mainland via Thailand , Cambodia , Laos and Vietnam north to southern China and south to Malaysia . It also settles in Singapore and Borneo , the Indonesian islands of Java , Sumatra , as well as the Lesser Sunda Islands and Sulawesi up to the Obi Islands , the easternmost occurrence of the black dragon. The water monitor lizards living in the Philippines , which were previously assigned to the species V. salvator , are now regarded as separate species.

As an opportunist, the sea monitor lives in a variety of habitats up to 1800  m above sea level; however, the species is more of a flatland inhabitant of up to 600  m above sea level and becomes very rare above 1000  m . Preferred natural habitats are brackish mangroves and forested river banks and wetlands in general. In addition, rainforests, monsoon forests and rarely drier habitats are inhabited. Clearly, black monitors are also able to inhabit anthropogenic landscapes such as plantations and urban areas.

Subspecies and systematics

Due to the unique features of the hemipenis , the bandy monitor complex is classified in the subgenus Soterosaurus . DNA analysis confirmed Soterosaurus as monophyletic ; the sister taxon to this subgenus is the Raunackenwaran ( Varanus rudicollis ).

For a long time, six to eight subspecies were recognized by the sea monitor, depending on the author. A revision by Koch (2004) and Koch et al. (2007) on the basis of morphological findings raised some of them to species status, only four were still classified as V. salvator ssp. classified. Koch et al. (2007) also restricted the range of the once most widespread subspecies V. s. salvator in Sri Lanka and assigned most of the other populations to V. s. macromaculatus too. Around three years later, Koch & Böhme (2010) described the new subspecies V. s. ziegleri , named after her colleague Thomas Ziegler . Thus, five subspecies are currently distinguished. The following list follows Koch et al. (2007) and Koch & Böhme (2010). Extensive discussions about variations and differences between the subspecies can also be found in these writings.

Former subspecies of the white monitor monitor are the Filipino taxa Varanus cumingi , Varanus marmoratus , Varanus palawanensis and Varanus nuchalis , as well as Varanus togianus from the Togian Islands and Sulawesi. It is to be expected that numerous other species and subspecies will be described; on Sulawesi and offshore islands, for example, many new color forms, which differ greatly from the basic pattern, have recently been discovered, which probably represent new subspecies of the black monitor monitor or also new species.

Way of life

behavior

Spindle monitors, here probably V. s. macromaculatus , are skilled climbers
For thermoregulation as well as for hunting, black tie monitors go into the water (here probably V. s. Macromaculatus )
Bindweed monitor in the water, in Hua Hin Thailand

Like all monitor lizards, the blind monitor is diurnal, mostly between 6 a.m. and 6 p.m. In the morning the animals sunbathe on sun-exposed areas or branches until around 9 a.m. They are most active in the early afternoon, the hottest time of the day. In the more northerly parts of the range they begin their activities later in winter and finish them earlier; in the parts of the range near the equator (e.g. Lesser Sunda Islands), such seasonal differences are unlikely to be pronounced. At night, water monitors hide in tree holes, on branches, in dense vegetation, in the water or in structures they have dug themselves. The buildings are tunnels that are on average 9.5 m long; the diameter of the entrance is around 40 cm to around 75 cm, the depth of a chamber at the end is 1.2–2.4 m. The temperature in such a building is lower and more stable than outside, and so these corridors are also used in the context of thermoregulation . Bindweed monitor also cool off in water. The animals actively regulate their body temperature, the preferred range is around 36–38 ° C.

In English they are called water monitors . In fact, with their laterally flattened oar tails, they are excellent swimmers and their choice of habitat is strongly tied to the water. Black monitors also hunt their prey in the water and are able to cross inlets between islands. The sea monitor was the first non-flying terrestrial vertebrate to repopulate the destroyed island of Krakatau six years after the volcanic eruption in 1883 . However, they also spend most of their time on land and are also excellent climbers.

Action spaces and social behavior

Like all monitor lizards, black lizards are loners. In various studies, depending on the specimen and location, action spaces ranging from 200 m² to 22.6  ha (= 226,000 m²) and in exceptional cases also 317,000 m² were determined. The action areas of the specimens overlap strongly, territorial behavior is very rare in the case of water monitors. It can be observed that sea monitor monitors in nutrient-rich areas such as mangroves have to use less space than sea monitor monitors in less suitable habitats. The extreme of 22.6 ha was determined in an oil palm plantation . For a large specimen on the Sungai-Dunsun Canal (Malaysia), it was also possible to record that it traveled over 2 km daily in search of food.

As with many monitor lizards, there are comment fights between the males for the privilege to mate during the mating season. If several individuals meet at a carcass or at a possible shelter, such fights (also between females and between females and males) establish a short-term dominance relationship for the use of the resource.

nutrition

The food spectrum of the white monitor monitor is strongly dependent on habitat and age. In mangroves, crabs and insects are the most important prey, preferably at low tide, while in oil palm plantations it is mainly insects and rodents. The food spectrum also fluctuates seasonally: in West Kalimantan the watering holes shrink during the dry season, so that fish are found in higher density than other prey and make up a larger proportion of the prey. In general, it can be said that black monitors are very opportunistic carnivores, whose food spectrum includes various insects, crustaceans , birds, reptiles, eggs (e.g. from birds, sea turtles, crocodiles), amphibians and fish, and occasionally carrion that is 100 m away can be tracked down. In addition, cannibalism occurs on smaller conspecifics, and tie monitors also eat the rubbish in the vicinity of human settlements, even sandwiches. Due to its size, the sea monitor can prey on fish up to 50 cm in length, and occasionally very large prey may also play a role. In 1970 a V. s. bivittatus reports that he had killed a Banteng's calf .

The black monitor catches its prey as an active chase, constantly searching large areas for prey. The monitor lizards apparently remember particularly productive hunting grounds to which they keep coming back. Small prey is caught in a rapid, leaping forward motion, crabs and eggs are dug up. In addition, people sometimes look for food in trees, and fish are stalked swimming underwater. Prey up to 50 cm in length can apparently be swallowed whole, large prey is occasionally fixed to the ground with the front legs and torn apart with the jaws.

In areas west of the Wallace Line , black tie monitors are the top predators in their habitats.

Reproduction and development

Reproduction calendar of the white monitor monitor on West Kalimantan, according to Auliya (2006). Red: mating, blue: laying eggs, green: hatching.

The reproduction of the black tie monitor in nature is still relatively incomplete researched. In tropical areas at the equator, the species reproduces with up to two clutches all year round. At the respective mating season, males are particularly active and look for females. In West Kalimantan, mating takes place at the beginning of the rainy season (October) and during the dry season (April – May), for more details see graphic on the right. From more northern parts of the distribution area, however, it is known that reproduction with only one clutch occurs in the dry season (India e.g. egg-laying June – July).

Clutches of female connective monitors comprise 5–40 eggs, with particularly large clutches being laid over several days. The females build nesting holes to lay their eggs, for example in sandy river banks and termite mounds, or they lay eggs in roots, between bamboo thickets or in hollow tree trunks. The eggs are typically 6.4–8.26 cm long and weigh 30–87.2 g. The young hatch after 7–9 months. Hatchlings are 28–32.5 cm long and weigh 21–50 g. Occasionally it has been observed that mother animals guarded their nests or that newly hatched young animals dig up. Scaly creepers usually show no care for young animals.

In nature, the young monitor lizards reach a total length of about 1 m within 2–3 years and are therefore sexually mature. Juvenile and subadult animals are more tree-dwelling than adults. From a length of 1.2 m, there is a strong increase in weight proportional to the increase in length, which is accompanied by a change to a terrestrial-semi-aquatic way of life. The life expectancy of the black tie monitor in nature is unknown; in captivity it can reach an age of up to 10 years and 8 months.

Black monitors and humans

Javanese boy with killed bandage monitor. Archive of the Amsterdam Tropical Museum , 1917/18.

The bandy monitor is systematically reproduced for the leather industry in Southeast Asia. Local traders usually let young men or poor farmers catch monitor lizards alive and hand them over to middlemen who take the monitor lizards to the large slaughterhouses and tanneries. Around 450,000 monitor lizards are legally shot annually, the actual trade in the monitor lizards, which are actually protected by CITES , is likely to be higher. Reptile leather is processed into numerous luxury products such as wristwatches and handbags. The number of specimens caught for the pet trade is limited in the case of the bandage monitor, as they are unsuitable for private terrarium keeping due to their size . The practices of the leather industry are criticized. Snow monitors are apparently stored for days with their legs tied together, and the hammer blows on the head used for slaughter do not always lead to direct death. Water monitors are regularly skinned alive, according to Koch (2010).

In addition, black monitors are hunted locally as meat suppliers. The extent of the persecution depends heavily on the local population: while the natives and the Christian population hunt the bandy monitor, Muslims and Buddhists do not eat monitor meat for religious reasons. In Singapore, on the other hand, it is believed that the white monitor monitor is poisonous. Various ethnic groups make traditional remedies from parts of the body of the bandage monitor.

In parts of the distribution area, especially Thailand , black tie monitors are very unpopular. This is due, among other things, to the fact that black monitors regularly invade chicken coops and capture the birds and their eggs there. Thai culture regards them as the lowest and most impure animals. The original Thai name for the bandy monitor is "hia" , which is an extremely vulgar swear word for people and is therefore subject to a language taboo . The euphemism "tua ngoen tua thong" is used to facilitate public conversations about the animal .

Hazard and protection

Population estimates are not available and the population trend is unknown but appears to be stable. Due to the stable population and the wide distribution, the Red List of Endangered Species of the IUCN classifies the black monitor monitor as harmless ( least concern ). Despite the progressive destruction of its habitats, the black monitor monitor can survive, as it can also colonize highly anthropogenic and polluted habitats and feed on the waste of civilization. Due to its short generation succession and high reproduction rate, it withstands the pressure of the leather industry, and the danger on roads (tie monitors are regularly run over) is not enough to seriously endanger the species.

The sea monitor lives in a number of protected areas and is listed in Appendix II of the Washington Convention on Species Protection . Further protective measures do not seem necessary at the moment.

Web links

Commons : Bindenwaran ( Varanus salvator )  - Collection of images, videos and audio files

supporting documents

Individual evidence

  1. ↑ a b c d e f g h i j k l m n o p q r s t M. Gaulke & H.-G. Horn (2004): Varanus salvator (nominate form) . In: ER Pianka & DR King (Eds.): Varanoid Lizards of the World , pp. 244-257. Indiana University Press, Bloomington & Indianapolis, ISBN 0253343666
  2. ↑ a b c d e M. A. Auliya (2006): Taxonomy, Life History and Conservation of Giant Reptiles in West Kalimantan . NTV, Münster, ISBN 3-937285-52-0
  3. ↑ a b c d A. Koch, M. Auliya, A. Schmitz, U. Kuch & W. Böhme (2007): Morphological Studies on the Systematics of South East Asian Water Monitors (Varanus salvator Complex): Nominotypic Populations and Taxonomic Overview . Mertensiella 16 ( Advances in Monitor Research III ), pp. 109-180
  4. ↑ a b c d A. Koch (2010): Underestimated and exploited: systematics, diversity and endemism of Southeast Asian black monitors . Koenigiana 4 (1), pp. 27-41
  5. ↑ a b T. C.-A. Ota & S. Makcha (2009): Geographical Distribution and Regional Variation of Varanus salvator macromaculatus in Thailand . Biawak 3 (4), pp. 134-143
  6. ^ A b A. Koch & W. Böhme (2010): Heading East: A new Subspecies of Varanus salvator from Obi Island, Maluku Province, Indonesia, with a Discussion about the Easternmost Natural Occurence of Southeast Asian Water Monitor Lizards . Russian Journal of Herpetology 17 (4), pp. 299-309
  7. ↑ a b A. Koch, M. Gaulke & W. Böhme (2010): Unraveling the underestimated diversity of Philippine water monitor lizards (Squamata: Varanus salvator complex), with the description of two new species and a new subspecies . Zootaxa 2446, pp. 1-54
  8. ↑ a b c d e f Varanus salvator in the endangered species Red List of IUCN 2010. Submitted By: Bennett, D., Gaulke, M., Pianka, ER, Somaweera, R. & Sweet, SS, 2009. Retrieved on 11 February 2011.
  9. ↑ a b c H.-G. Horn & M. Gaulke (2004): Varanus salvator (subspecies) . In: ER Pianka & DR King (Eds.): Varanoid Lizards of the World , pp. 258-271. Indiana University Press, Bloomington & Indianapolis, ISBN 0253343666
  10. ↑ JC Ast (2001): Mitochondrial DNA Evidence and Evolution in Varanoidea (Squamata) . Cladistics 17, pp. 211-226
  11. ↑ a b A. Koch & W. Böhme: Annual Report 2007/2008 of the Research Museum Koenig - Phylogeography of the Bindweed Monitor of Sulawesi. (PDF) pp. 7–10 , accessed on June 26, 2018 .
  12. ^ I. Thornton (1997): Krakatau: The Destruction and Reassembly of an Island Ecosystem . Harvard University Press, ISBN 0674505727
  13. ↑ a b D. MS Suranhan Karunarathna, AA Thasun Amarasinghe & EM Kasun B. Ekanayake (2008): Observed Predation on a Suckermouth Catfish (Hypostomus plecostomus) by a Water Monitor (Varanus salvator) in Bellanwila-Attidiya Sanctuary . Biawak 2 (1), pp. 37-39
  14. ↑ H. de Lisle (2007): Observations on Varanus s. Salvator in North Sulawesi . Biawak 1 (2), pp. 59-66
  15. ↑ a b M. Stanner (2010): Mammal-like Feeding Behavior of Varanus salvator and its Conservational Implications . Biawak 4 (4), pp. 128-131
  16. ↑ a b A. Koch (2010): Bestial treatment of large Indonesian reptiles for Western luxury products . Reptilia 15 (6), pp. 3 & 6
  17. ↑ P. Duengkae & Y. Chuaynkern (2009): A Road-killed Water Monitor Varanus salvator macromaculatus: Negative Impact from the Forest Route in Khao Yai National Park, Thailand . Biawak 3 (1), pp. 23-25

literature

  • MA Auliya (2006): Taxonomy, Life History and Conservation of Giant Reptiles in West Kalimantan . NTV, Münster, ISBN 3-937285-52-0
  • M. Gaulke, W. Erdelen & F. Abel (1999): A Radio-Telemetric Study of the Water Monitor Lizard (Varanus salvator) in North Sumatra, Indonesia . Mertensiella 11 ( Advances in Monitor Research II ), pp. 63-78
  • M. Gaulke & H.-G. Horn (2004): Varanus salvator (nominate form) . In: ER Pianka & DR King (Eds.): Varanoid Lizards of the World , pp. 244-257. Indiana University Press, Bloomington & Indianapolis, ISBN 0253343666
  • H.-G. Horn & M. Gaulke (2004): Varanus salvator (subspecies) . In: ER Pianka & DR King (Eds.): Varanoid Lizards of the World , pp. 258-271. Indiana University Press, Bloomington & Indianapolis, ISBN 0253343666
  • A. Koch, M. Auliya, A. Schmitz, U. Kuch & W. Böhme (2007): Morphological Studies on the Systematics of South East Asian Water Monitors (Varanus salvator Complex): Nominotypic Populations and Taxonomic Overview . Mertensiella 16 ( Advances in Monitor Research III ), pp. 109-180
  • A. Koch & W. Böhme (2010): Heading East: A new Subspecies of Varanus salvator from Obi Island, Maluku Province, Indonesia, with a Discussion about the Easternmost Natural Occurence of Southeast Asian Water Monitor Lizards . Russian Journal of Herpetology 17 (4), pp. 299-309
This version was added to the list of articles worth reading on March 1, 2011 .