Rock monitor

{{short description|Species of reptile}} {{speciesbox | image = White-throated Monitor (Varanus albigularis) (32184691034).jpg | image_caption = White-throated monitor at Mountain Zebra National Park, South Africa | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=Beraduccii, J. |author2=Msuya, C.A. |author3=Howell, K. |author4=Ngalason, W. |year=2021 |title=''Varanus albigularis'' |volume=2021 |article-number=e.T22473612A22473630 |doi=10.2305/IUCN.UK.2021-2.RLTS.T22473612A22473630.en |access-date=19 November 2021}}</ref> | status2 = CITES_A2 | status2_system = CITES | genus = Varanus | parent = Varanus (Polydaedalus) | species = albigularis | authority = (Daudin, 1802)<ref name="FMD">{{cite journal|author-link=François Marie Daudin|author=Daudin, FM |year=1802|title=Histoire Naturelle, Génerale et Particulière des Reptiles; Ouvrage faisant suite à l'Histoire Naturelle, générale et particulière, composée par LECLERC DE BUFFON, et redigée par C. S. SONNINI, membre de plusieurs Sociétés savantes|volume=Tome Troisième|location=Paris|journal=F. Dufart|pages=72-75 + Plate XXXII|lang=fr}}</ref><ref name="ITIS">{{ITIS|id=716498|taxon=''Varanus albigularis ''|access-date=22 August 2008}}</ref> | synonyms = {{collapsible list| *''Tupinambis albigularis'' {{small|Daudin, 1802}} *''Tupinambis indicus'' {{small|Daudin, 1802}} *''Monitor albigularis'' {{small|— Gray, 1831}} *''Varanus albogularis'' {{small|— A.M.C. Duméril & Bibron, 1836}} *''Regenia albogularis'' {{small|— Günther, 1861}} *''Varanus albigularis'' {{small|— Boulenger, 1885}} *''Varanus exanthematicus albigularis'' {{small|— Schmidt, 1919}} }} *''Varanus exanthematicus ionidesii'' {{small|— Raymond Ferdinand Laurent, 1964}} *''Varanus albigularis'' {{small|— Böhme, 1988}} | synonyms_ref = <ref name=RDB/> }}

The '''rock monitor''' ('''''Varanus albigularis''''') is a species of monitor lizard in the family Varanidae. The species is endemic to Sub-Saharan Africa, where, on average, it is the largest lizard found on the continent. It is called ''leguaan'' or ''likkewaan'' in some areas.

==Taxonomy== thumb|''V. albigularis'' First described by François Marie Daudin in 1802,<ref name="FMD"/> ''V. albigularis'' had been classified as a subspecies of ''V. exanthematicus'',<ref name="mistake">{{cite journal |author-link=Raymond Ferdinand Laurent|author=Laurent, RF |year=1964|title=A new subspecies of ''Varanus exanthematicus'' (Sauria, Varanidae)|journal=Breviora|volume=199|pages=1–5}}.</ref> but has since been declared a distinct species based on differences in hemipenal morphology.<ref>{{cite journal|author-link=:de:Wolfgang Böhme (Zoologe) |author=Böhme, W. |year=1991|title=New finding on the hemipenal morphology of monitor lizards and their systematic implications |journal=Mertensiella |volume=2 |pages=42–49}}</ref> The generic name ''Varanus'' is derived from the Arabic word ''waral'' ورل (English: "monitor"). The specific name ''albigularis'' comes from a compound of two Latin words, ''albus'' (meaning "white") and ''gula'' ("throat").

Subspecies of ''V. albigularis'' are: *White-throated monitor, ''V. a. albigularis'' *Angolan white-throated monitor, ''V. a. angolensis'' *Eastern white-throated monitor, ''V. a. microstictus'' *Black-throated monitor, ''V. a. ionidesi''<ref name="RDB">"''Varanus albigularis'' ". The Reptile Database. www.reptile-database.org. [http://reptile-database.reptarium.cz/species?genus=Varanus&species=albigularis]</ref> (but may be synonymous with ''V. a. microstictus'')

==Description== ''Varanus albigularis'' is on average the most massive lizard in Africa, as adult males average about {{convert|6|to|8|kg|lb|abbr=on}} and females weigh from {{convert|3.2|to|5|kg|lb|abbr=on}}.<ref>{{cite web|url=http://reptiliana.wordpress.com/2008/03/01/white-throated-monitor-varanus-albigularis/|title=White Throated Monitor – ''Varanus albigularis ''|publisher=Reptiliana: Ultimate Reptile Resource|access-date=2013-06-06|date=March 2008}}</ref><ref name="WAZA">{{cite web|url=http://www.waza.org/en/zoo/choose-a-species/reptiles/lizards-and-tuatara/varanus-exanthematicus-albigularis|title=African Savannah Monitor – ''Varanus exanthematicus albigularis ''|publisher=WAZA : World Association of Zoos and Aquariums|access-date=2013-06-06|archive-date=2012-05-25|archive-url=https://web.archive.org/web/20120525135400/http://www.waza.org/en/zoo/choose-a-species/reptiles/lizards-and-tuatara/varanus-exanthematicus-albigularis|url-status=dead}}</ref><ref>Gardner BR, Barrows MG (2010). "Yolk coelomitis in a white-throated monitor lizard (''Varanus albigularis'')". ''Journal of the South African Veterinary Association'' '''81''' (2): 121-122.</ref> Large mature males can attain weights of {{convert|15|to|17|kg|lb|abbr=on}}, which would make it slightly smaller than the Nile monitor by maximum size.<ref name=monitor>{{cite web|url=http://www.monitor-lizards.net/species/polydaedalus/albigularis.html|title=''Varanus albigularis ''|publisher=Monitor-Lizards.net|access-date=2013-06-06|archive-url=https://web.archive.org/web/20120731221235/http://www.monitor-lizards.net/species/polydaedalus/albigularis.html|archive-date=2012-07-31}}</ref> It is the second longest African lizard after the Nile monitor. Mature specimens typically measure {{convert|0.85|to|1.5|m|ftin|sp=us}}.<ref name="WAZA"/><ref name= monitor/> The head and neck are the same length, and are distinct from each other. The bulbous, convex snout gives an angular, box-like appearance. The forked tongue is pink or bluish, and the body scales are usually a mottled gray-brown with yellowish or white markings.<ref name="GA">{{cite book |last=Alexander |first=Graham |title=A Guide to the Reptiles of Southern Africa |author2=Marais, Johan |publisher=Struik Publishers. 408 pp |year=2008 |isbn=978-1-77007-386-9 |location=South Africa}}</ref> Exceptionally large specimens reach {{convert|2|m|ftin|sp=us}} in total length (including tail), with its tail and body being of equal size.<ref name="VC">{{cite book|last=Carruthers|first=Vincent|title=The Wildlife of Southern Africa: The Larger Illustrated Guide to the Animals and Plants of the Region|publisher=Struik Publishers. 320 pp|date=June 5, 2008|location=South Africa|isbn=978-1-77007-199-5}}</ref>

==Geographic range and habitat== ''V. albigularis'' is found in Central Africa (Democratic Republic of the Congo/Zaire), Southern Africa (Namibia, Botswana, Republic of South Africa, Eswatini, Zimbabwe, Mozambique, Zambia, Angola), East Africa and the African Great Lakes region (Burundi, Kenya, Uganda, Tanzania), and the Horn of Africa (Ethiopia, Somalia). ''V. albigularis'' is found in a variety of arid habitats, including steppes, grasslands and savanna, and may frequent rock ''kopje'' (inselbergs) formations that dot the landscape. They are generally absent from desert interiors, rainforests and thick scrub forests.<ref name="GA"/>

== Diet == ''V. albigularis'' are generalists, feeding opportunistically on a broad variety of prey in the wild, such as other lizards, amphibians, birds, snakes, tortoises, eggs and small mammals.<ref>{{cite web|date=December 2012|volume=58:15-16|author=Werner Conradie|work=African Herp News : Newsletter of the Herpetological Association of Africa |title=VARANIDAE ''Varanus albigularis'' (Daudin, 1802) Rock Monitor DIET |url=https://www.researchgate.net/publication/280597661 |via=ResearchGate}}</ref><ref>{{cite web | url=https://biocyclopedia.com/index/monitor_lizards/varanus_albigularis.php | title=Varanus Albigularis }}</ref> Tortoises make up a significant part of their diet, and are swallowed whole due to the hard shell. Otherwise, this species consumes very little vertebrate prey, eating primarily invertebrates, especially millipedes, beetles, molluscs, orthopterans and scorpions.<ref>{{cite web | url=https://biocyclopedia.com/index/monitor_lizards/varanus_albigularis.php | title=''Varanus albigularis''}}</ref> Millipedes for example form nearly a quarter of their diet; the monitors are apparently resistant to its poisonous secretions. They are not averse to occasionally scavenging the corpses of vertebrate prey, even those as large as vervet monkeys, which are sometimes torn to pieces by "death rolling" like a crocodilian prior to consumption.<ref>{{Cite journal|last=Krebs|first=Uwe|date=January 2019|title=Observations and Experiments on "Spinning Behavior" in ''Varanus albigularis''|journal=Biawak|volume=13|issue=1|pages=54–61}}</ref> Live vertebrate prey other than tortoises are usually too fast to catch for these monitors, and therefore form very little of their diet.<ref>{{Cite journal|last=Dalhuijsen|first=Kim|date=10 December 2013|title=A comparative analysis of the diets of ''Varanus albigularis'' and ''Varanus niloticus'' in South Africa|journal=African Zoology|volume=49|issue=1|pages=84–93}}</ref> This contrasts with what is often a diet of mostly vertebrates in captivity, such as rodents, poultry or fish.<ref>{{cite web | url=https://www.reptiledirect.com/black-throated-monitor/ | title=Black-Throated Monitor 101: Care, Size, Diet & More! | date=26 July 2022 }}</ref>

== Predators == Natural predators of adult rock monitors include martial eagles and leopards.<ref name = KS>{{cite web|title=Eagle Rips Lizard's Eyes Apart As it Tries to Escape|url=https://latestsightings.com/single-post/eagle-rips-lizards-eyes-apart-as-it-tries-to-escape-kruger-national-park|publisher=Kruger sighting|date=September 15, 2020}}</ref><ref>{{cite journal|author=Radloff, Frans GT|author2= Johan T. Du Toit |name-list-style=and |title=Large predators and their prey in a southern African savanna: a predator's size determines its prey size range|journal=Journal of Animal Ecology|volume=73|issue=3|year=2004|pages=410–423|doi= 10.1111/j.0021-8790.2004.00817.x |bibcode= 2004JAnEc..73..410R }}</ref>

==Intelligence== An intelligent lizard, several specimens of ''V. albigularis'' have demonstrated the ability to count as high as six in an experiment conducted by Dr. John Philips at the San Diego Zoo in 1999.<ref name="count">{{Cite book|last1=Pianka|first1=Eric R.|author-link=Eric Pianka|last2=Vitt|first2=Laurie J.|title=Lizards: Windows to the Evolution of Diversity|place=Berkeley, Los Angeles, London|publisher=University of California Press. 346 pp|year=2003|isbn=978-0-520-23401-7|url-access=registration|url=https://archive.org/details/lizardswindowsto00pian}}</ref> Philips offered varying numbers of snails, and the monitors were able to distinguish numbers whenever one was missing.<ref name ="King">{{cite book|author=King, Dennis|author2= Green, Brian |year=1999|title=Goannas: The Biology of Varanid Lizards|publisher=University of New South Wales Press|isbn=0-86840-456-X|page=43}}</ref><ref>''The Weekend Australian''. July 24–25, 1999, p. 12.</ref>

==Folklore== People living with the HIV/AIDS virus in Yumbe District of Uganda have been reported injecting themselves with the blood of rock monitors, which they believe to be a cure for the virus. Many are reportedly discontinuing anti-retroviral therapy to pursue this anecdotal treatment.<ref name="aids">{{Cite journal |date=February 2008 |title=Ugandans turn to varanid lizard blood for AIDS cure |url=http://www.varanidae.org/Vol_2_No_1.pdf |journal=Biawak |publisher=INTERNATIONAL VARANID INTEREST GROUP |volume=2 |issue=1 |access-date=2008-08-27}}</ref>

As a result, ''V. albigularis'' is reported to have become an expensive item in the Ugandan black market, selling for more than 175 US$ each.<ref name="aids"/>

==References== {{Commons category|Varanus albigularis|''Varanus albigularis''}} {{Wikispecies|Varanus (Polydaedalus) albigularis|''Varanus albigularis''}} {{Reflist}}

==External links== *[http://www.reptilespark.com/home/varanus/1.htm Photo of ''Varanus albigularis'']

==Further reading== *Bayless, Mark K. (1992). "The Necropsy and internal Anatomy of a white-throated monitor lizard (''Varanus albigularis'' Daudin, 1802)". ''VaraNews'' '''2''' (1): 5-6.

Category:Varanus Category:Reptiles described in 1802 Category:Taxa named by François Marie Daudin