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{{Short description|Species of lizard}}
{{Distinguish|Asian water monitor}}
{{speciesbox
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn">{{Cite iucn | author = Papenfuss, T. | author2 = Shafiei Bafti, S. | author3 = Sharifi, M. | author4 = Bennett, D. | author5 = Sweet, S.S. | name-list-style=amp | title = ''Varanus bengalensis'' | volume = 2010 | page = e.T164579A5909661 | date = 2010 | doi = 10.2305/IUCN.UK.2010-4.RLTS.T164579A5909661.en }}</ref>
| name = Bengal monitor
| image = Bengal monitor (Varanus bengalensis) Photograph by Shantanu Kuveskar.jpg
| image_caption = Mangaon, Maharashtra, India
| genus = Varanus
| parent = Varanus (Empagusia)
| species = bengalensis
| authority = ([[Daudin]], 1802)
| synonyms = ''Tupinambis bengalensis''
}}

The '''Bengal monitor''' (''Varanus bengalensis'') or '''common Indian monitor''', is a [[monitor lizard]] found widely distributed over the [[Indian Subcontinent|Indian subcontinent]], as well as parts of [[Southeast Asia]] and [[West Asia]]. This large lizard is mainly [[Terrestrial animal|ground-dwelling]], and its length can range from about 61 to 175 cm from the tip of the snout to the end of the tail. Young monitors may be more [[arboreal]], but adults mainly hunt on the ground, [[prey]]ing mainly on [[arthropods]], but also taking small terrestrial [[vertebrate]]s, ground [[bird]]s, [[Egg (biology)|eggs]] and [[fish]]. Although large monitors have few [[predator]]s apart from humans who hunt them for meat, younger individuals are hunted by many predators.

== Description ==
[[File:Bengal Monitor (Varanus bengalensis) Juvenile. (28230373818).jpg|alt=|left|thumb|Juveniles are patterned and more colourful]]
The Bengal monitor can reach 175 cm with a snout-to-vent length (SVL) of 75 cm and a tail of 100 cm. Males are generally larger than females. Heavy individuals may weigh nearly 7.2 kg.<ref>Auffenberg (1994):14-15</ref> The populations of monitors in India and Sri Lanka differ in the scalation from those of Myanmar; these populations were once considered subspecies of the Bengal monitor, but are now considered two species within the ''V. bengalensis'' species complex.<ref>{{Cite journal|last=Böhme|first=Wolfgang|date=2003-01-01|title=Checklist of the living lizards of the world (family Varanidae)|url=https://www.researchgate.net/publication/237517031|journal=BMC Evolutionary Biology - BMC EVOL BIOL|volume=341 |via=ResearchGate}}</ref>{{verify source|date=October 2020}} What was once the nominate subspecies, ''V. bengalensis'', is found west of Myanmar, while the [[Clouded monitor|clouded monitor (''V. nebulosus'')]] is found to the east. Clouded monitors can be differentiated by the presence of a series of enlarged scales in the supraocular region. The number of ventral scales varies, decreasing from 108 in the west to 75 in the east (Java).<ref>Auffenberg (1994):24</ref>
[[File:SL Bundala NP asv2020-01 img22.jpg|left|thumb|Adult, [[Bundala National Park]]]][[File:A Monitor Lizard.jpg|thumb|Adult]][[File:Bengal monitor at Anawilundawa Bird Sanctuary - (A Mischievous Grin).jpg|thumb|Showing forked tongue]][[File:Monitor lizard image.jpg|thumb|Eating egg]][[File:Bengal Monitor Lizard.JPG|thumb|Adult, [[Kaziranga National Park]]]][[File:Common Indian Monitor or Bengal monitor Varanus bengalensis Karnala Maharashtra (2).JPG|thumb|Climbing tree]]
Young monitor lizards are more colourful than adults. Young have a series of dark crossbars on the neck, throat and back. The belly is white, banded with dark crossbars and are spotted with grey or yellow (particularly in the eastern part of the range). On the dorsal surface of young monitors, there are a series of yellow spots with dark transverse bars connecting them. As they mature, the ground colour becomes light brown or grey, and dark spots give them a speckled appearance. Clouded monitor hatchlings by comparison tend to have a series of backward-pointing, V-shaped bands on their necks.<ref>Auffenberg (1994):39</ref>

Bengal monitors have external nostril openings (nares) that is slit-like and oriented near horizontal, and positions between the eye and the tip of the snout. The nares can be closed at will, especially to keep away debris or water.<ref>Auffenberg (1994):22</ref> The scales of the skin are rougher in patches and on the sides, they have minute pits, especially well distributed in males.<ref>Auffenberg (1994):36</ref> These scales with micropores have glandular structures in the underlying dermal tissue and produce a secretion which may be a pheromone-like substance. Like other monitors, Bengal monitors have a forked tongue similar to snakes. The function is mainly sensory, and is not very involved in the transport of food down the throat. Bengal monitors have fat deposits in the tail and body that serve them in conditions when prey are not easily available.

The lungs have spongy tissue unlike the sacs of other [[sauria]]ns. This allows for a greater rate of gas exchange and allows a faster metabolic rate and higher activity levels. Like all monitors, they have subpleurodont teeth, meaning the teeth are fused to the inside of the jaw bones.<ref>Auffenberg (1994):50</ref> The teeth are placed one behind another, and there are replacement teeth behind and between each functional tooth (polyphyodont). The maxillary and dentary teeth are laterally compressed, sometimes with a slightly serrate cutting edge, while the premaxillary teeth are conical. There are 78 premaxillary teeth, 10 maxillary and 13 dentary teeth. Replacement teeth move forward and about four replacements happens each year for a tooth.<ref>Auffenberg (1994):51</ref> While monitor lizards are venomous, there are no reports of the effects of venom in Bengal monitors other than a very controversial case report of fatal renal failure as a result of envenomation from this species.<ref>{{Cite journal|last=White|first=Julian|last2=Weinstein|first2=Scott A.|date=2015-04-21|title=Reply to Vikrant and Verma about "Monitor Lizard Envenoming"|url=http://www.tandfonline.com/doi/full/10.3109/0886022X.2015.1006116|journal=Renal Failure|language=en|volume=37|issue=4|pages=740–741|doi=10.3109/0886022X.2015.1006116|issn=0886-022X}}</ref>

== Distribution and habitat ==

The species ranges from Iran to Java, among the most widely distributed of monitor lizards as they are eurytopic and adaptable to a range of habitats.<ref name=":0" /> It is found in river valleys in eastern [[Iran]], [[Afghanistan]], [[India]], [[Nepal]], [[Sri Lanka]], [[Pakistan]], [[Bangladesh]] and [[Burma]]. The closely related species, the [[clouded monitor]], occurs in southern [[Burma]], [[Vietnam]], [[Cambodia]], [[Thailand]], [[Malaysia]], [[Sumatra]], [[Java]] and the [[Sunda Islands]]. They have not been confirmed on Sumatra, and have been found to be absent from the [[Andaman Islands]].<ref>Auffenberg (1994):86</ref>

The species is mainly distributed through lower elevations below an altitude of 1500 metres, and is found both in dry semiarid desert habitats to moist forest. They are often found in agricultural areas.<ref name="iucn" /><ref>Auffenberg (1994):103-118</ref>

== Ecology and behaviour ==

Bengal monitors are usually solitary and usually found on the ground, although the young are often seen on trees. Clouded monitors by contrast have a greater propensity for tree climbing. Bengal and [[yellow monitor]]s are sympatric but are partially separated by their habitat as Bengal monitors prefers forest over agricultural areas.<ref name="herpconbio.org">Ghimire, H. R., & Shah, K. B. (2014). Status and habitat ecology of the Yellow Monitor, Varanus flavescens, in the Southeastern part of Kanchanpur District, Nepal. Herpetological Conservation and Biology, 9(2), 387-393. http://www.herpconbio.org/Volume_9/Issue_2/Ghimire_Shah_2014.pdf</ref> Bengal monitors shelter in burrows they dig or crevices in rocks and buildings, whilst clouded monitors prefer tree hollows. Both species will make use of abandoned termite mounds. Bengal monitors are [[Diurnality|diurnal]] like other monitors, becoming active around 6 AM and bask in the morning sun.<ref>Auffenberg (1994):138-145</ref> During winter in the colder parts of their range, they may take shelter and go through a period of reduced metabolic activity.<ref>Auffenberg (1994):147</ref> They are not territorial, and may change their range seasonally in response to food availability.<ref>Auffenberg (1994):175</ref>

They are usually shy and avoid humans. They have keen eyesight and can detect human movement nearly 250 m away. When caught, a few individuals may bite, but rarely do so.<ref>Auffenberg (1994):182</ref>

Although they are found on agricultural land, they prefer forests with large trees.<ref name="herpconbio.org" /> Generally, high ground cover with large trees are favorable areas.<ref name="Ghimire and Phuyal 2013">{{cite journal |author=Ghimire, H. R. |last2=Phuyal, S. |year=2013 |title=Impacts of community forestry on the Bengal monitor, ''Varanus bengalensis'' (Daudin, 1802): an empirical study from Nepal |journal=Biawak |volume=7 |issue=1 |pages=11–17 |url=http://varanidae.org/7_1__Ghimire_and_Phuyal.pdf}}</ref>

Captives have been known to live for nearly 22 years.<ref>Auffenberg (1994):180</ref> Predators of adults include pythons, mammalian predators and birds. A number of ectoparasites and endoparasites are recorded.

=== Breeding ===
Females may be able to retain sperm, and females held in confinement have been able to lay fertile eggs.<ref>Auffenberg (1994):221</ref> Some species of monitor lizards such as the [[Nile monitor]] have additionally demonstrated to be capable of [[parthenogenesis]]. The main breeding season is June to September, but males begin to show combat behaviour by April. Females dig a nest hole in level ground or a vertical bank and lay the eggs inside, filling it up and using their snouts to compact the soil. The females often dig false nests nearby and shovel soil around the area. They sometimes make use of a termite mound to nest. A single clutch of about 20 eggs are laid. The eggs hatch in 168 to nearly as long as 254 days.<ref>Auffenberg (1994):230-247</ref> About 40-80% of the eggs may hatch.
=== Locomotion ===
They are capable of rapid movement on the ground. Small individuals may climb trees to escape, but larger ones prefer to escape on the ground. They can climb well. On the ground, they sometimes stand on the hind legs to get a better view or when males fight other males.<ref>Auffenberg (1994):183</ref> They can also swim well and can stay submerged for at least 17 minutes.<ref>Auffenberg (1994):185</ref> They can use both trees and bushes for shelter.<ref name="Ghimire and Phuyal 2013"/>

=== Feeding ===
Bengal monitors tend to remain active the whole day. Large adults may ascend vertical tree trunks, where they sometimes stalk and capture roosting bats. The species is a generalist, and feeds on a varied diet of invertebrates and vertebrates. Invertebrate prey mostly consists of beetles and their larvae followed by orthopterans, but also maggots, caterpillars, centipedes, scorpions, crabs, crayfish, snails, termites, ants, and earwigs. Larger individuals in addition to invertebrates also eat a large amount of vertebrate prey, including toads and frogs and their eggs, fish, lizards, snakes, rats, squirrels, hares, musk shrews, and birds. Hares and rodents such as [[Lesser bandicoot rat|Indian bandicoot rats]] are often caught by digging them out of their nests. Diet may differ based on season and locality, for example, they often forage for fish and aquatic insects in streams during the summer, and individuals in Andhra Pradesh eat mostly frogs and toads. Bengal monitors will also scavenge carrion, and sometimes congregate when feeding on large carcasses such as that of deer.<ref name=":0">{{Cite journal|last1=Losos|first1=Jonathan B.|last2=Greene|first2=Harry W.|date=1988-12-01|title=Ecological and evolutionary implications of diet in monitor lizards|url=https://academic.oup.com/biolinnean/article/35/4/379/2646908|journal=Biological Journal of the Linnean Society|language=en|volume=35|issue=4|pages=379–407|doi=10.1111/j.1095-8312.1988.tb00477.x|issn=0024-4066}}</ref><ref>Auffenberg (1994):267</ref> In areas where livestock are common, they often seek out dung to forage for beetles and other insects.<ref>Auffenberg (1994):349</ref><ref>{{cite journal |author1=Rahman K. M. M. |author2=Rakhimov I. I. |year=2015 |title=Habitat preference and feeding ecology of the Bengal monitor (''Varanus bengalensis'') in Natore, Bangladesh |journal=International Research Journal |series=Part 3 |volume=11 |issue=42 |pages=96–98 |doi=10.18454/IRJ.2015.42.212 }}</ref>

== In culture ==
[[File:Varanus.jpg|thumb|250px|Comparison to water monitor (''Varanus salvator'')|alt=]]
The lizard is known as ''bis-cobra'' in western India, ''Goyra'' in [[Rajasthan]], {{transl|bn|guishaap}} or {{transl|bn|goshaap}} in [[West Bengal]] and [[Bangladesh]], ''goh'' in [[Punjab, India|Punjab]] and [[Bihar]], as ''ghorpad'' in [[Maharashtra]] and as ''Thalagoya''<ref name="Abayartna & Mahaulpatha 2006">{{cite journal |last1=Abayaratna |first1=M.G.T.H |last2=Mahaulpatha |first2=W.A. Dharshani |date=2006 |title=Activity budgets and habitat preference of land monitor, Thalagoya Varanus bengalensis in a residential area |url=http://dl.sjp.ac.lk/dspace/bitstream/123456789/1044/1/Activity%20budgets%20and%20habitat.pdf |journal=Vidyodaya Journal of Science |volume=13 |page=127 |access-date=27 January 2015 |archive-url=https://web.archive.org/web/20150403071136/http://dl.sjp.ac.lk/dspace/bitstream/123456789/1044/1/Activity%20budgets%20and%20habitat.pdf |archive-date=3 April 2015 |url-status=dead }}</ref> in Sri Lanka. Folk mythology across the region includes the idea that these lizards, though actually harmless, are venomous, and in Rajasthan, the locals believe that the lizards become venomous only during the rainy season.<ref name="Auffenberg 1994:58">Auffenberg (1994):58</ref> Monitor lizards are hunted, and their body fat, extracted by boiling, is used in a wide range of folk remedies.<ref>Auffenberg (1994):appendix</ref>

In Sri Lanka, the [[Asian water monitor|water monitor (Kabaragoya)]] is considered venomous and dangerous when confronted, while the Bengal monitor (Thalagoya) is considered harmless and rather defenseless. Land monitor meat is considered edible (especially by indigenous Veddah and Rodiya people) while water monitor meat is not. Killing a land monitor is usually considered a cowardly act, and is frequently referred to folklore along with other harmless reptiles such as [[Ptyas mucosa|rat snakes]] (Garandiya).<ref>''Sri Lankan Lizards: kabaragoyas & Thalagoyas The concise guide to the Anglo-Sri Lankan lexicon'' by Richard Boyle, at http://www.lankalibrary.com/wlife/kabara.htm (Accessed: 29.10.2016.)</ref><ref>''Thalagoya Vs. Kabaragoya'' by Maryam Azwer, at http://roar.lk/environment-wildlife/thalagoya-vs-kabaragoya/ (Accessed 29.10.2016)</ref>

A clan in Maharashtra called ''Ghorpade'' claims that the name is derived from a legendary founder [[Maratha]] [[Koli people|Koli]]<ref>{{Cite book|url=https://books.google.com/books?id=QNA-AQAAIAAJ&q=Tanaji|title=Histories for the Subordinated|last=Hardiman|first=David|date=2007|publisher=Seagull Books|isbn=9781905422388|language=en}}</ref> leader [[Tanaji Malusare]] who supposedly scaled a fort wall using a monitor lizard tied to a rope.<ref>{{cite journal |last=Vidal |first=G. W. |date=1888 |title=The Bis Cobra |url=https://archive.org/stream/JournalOfTheBombayNaturalHistorySociety3_2/JBNHS3_2#page/n5/mode/2up |journal=Journal of the Bombay Natural History Society |volume=3 |issue=2 |pages=71–82}}</ref>

The Bengal monitor's belly skin has traditionally been used in making the drum head for the ''[[kanjira]]'' (known as ''Dimadi'' in Maharashtra), a South Indian percussion instrument.<ref name="Khati1998">{{cite book |last=Khati |first=Anand S. |date=1998 |title=National parks of India |url=https://books.google.com/books?id=KJUz97Z5LA0C |publisher=Pelican Creations International |page=323 |isbn=978-81-86738-00-9 |access-date=30 December 2012 }}</ref>

== Conservation ==
[[File:Varanus bengalensis roadkill 01.jpg|thumb|Bengal monitor roadkill]]
While it is assessed LC (Least Concern) by the IUCN 2009, the assessment currently requires updating. The Bengal monitor is listed as Appendix I of CITES and Schedule I of the 1972 Wildlife Protection Act. The wild population is decreasing as it is hunted for both consumption and medicinal purposes. As it is adaptable to a range of habitats, the threat of habitat degradation is relatively less prominent and is superseded by the threat of [[agricultural pollution]], as pesticides reduce the availability of prey. In Iran, it is also sometimes killed due to being seen as a dangerous threat.<ref name="iucn" />
{{-}}

== Notes ==
{{Reflist|30em}}

==References==
* {{cite book |last=Auffenberg |first=Walter |author-link=Walter Auffenberg |date=1994 |title=The Bengal Monitor |publisher=University Press of Florida |page=494 |isbn=0-8130-1295-3 }}
* {{cite journal |last=Auffenberg |first=W. |date=30 July 1979 |title=Intersexual differences in behaviour of captive ''Varanus bengalensis'' (Reptilia, Lacertilia, Varanidae) |journal=Journal of Herpetology |volume=13 |issue=3 |pages=313–315 |doi=10.2307/1563325 |jstor=1563325}}
* Auffenberg, W. 1979 Research on monitor lizards. Tiger Paper 6(4):20-21.
* Auffenberg, W. 1981 Combat behaviour in ''Varanus bengalensis''. J.Bombay N.H.S. 78(1):54-72.
* Auffenberg, W. 1983 The burrows of ''Varanus bengalensis''. Rec. Zool. Surv. India 80:375-385.
* Auffenberg, W. 1983 Courtship behaviour in ''Varanus bengalensis''. In Advances in Herpetology and Evolutionary Biology: Essays in Honor of Ernest E. Williams (Rhodin & Myata eds.): 535–551.
* Auffenberg, W. 1983 Notes on feeding behaviour of ''Varanus bengalensis''. J. Bombay N.H.S. 80 (2): 286–302.
* Auffenberg, W. 1986. The Indian monitor lizard. Sanctuary Asia. 6 (4):327-333.
* Ghimire, H. R., & Shah, K. B. (2014). Status and habitat ecology of the Yellow Monitor, ''Varanus flavescens'', in the Southeastern part of Kanchanpur District, Nepal. Herpetological Conservation and Biology, 9(2), 387–393. http://www.herpconbio.org/Volume_9/Issue_2/Ghimire_Shah_2014.pdf
* Mertens, R. 1942. Ein weiterer neuer Warane aus Australien. Zool. Anz. 137: 41-44

== External links ==
{{Commons category|Varanus bengalensis}}
* [http://mampam.50megs.com/monitors/bengalensis.html The online Little Book of Monitor Lizards]

{{Varanoidea}}

{{Taxonbar|from=Q756805}}

[[Category:Monitor lizards]]
[[Category:Lizards of Asia]]
[[Category:Reptiles of India]]
[[Category:Reptiles of Nepal]]
[[Category:Reptiles of Sri Lanka|Monitor]]
[[Category:Reptiles of Bangladesh]]
[[Category:Reptiles of Myanmar]]
[[Category:Reptiles of Laos]]
[[Category:Reptiles of Vietnam]]
[[Category:Reptiles of Cambodia]]
[[Category:Reptiles of Thailand]]
[[Category:Reptiles of Malaysia]]
[[Category:Reptiles of Brunei]]
[[Category:Reptiles of Indonesia]]
[[Category:Reptiles of Iran]]
[[Category:Reptiles described in 1802]]

Bengal monitor - Revision history

CleanupBot at 04:06, 11 December 2022