Overview
Distribution
Range Description
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Geographic Range
Varanus exanthematicus, or the savannah monitor, is found throughout most of Africa south of the Sahara (Steel 1996). It is found in west and central parts of Africa and southward toward Zaire (Rogner 1997).
Biogeographic Regions: ethiopian (Native )
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Distribution: Mauritania, Senegal, Gambia, Guinea Bissau, Guinea, Sierra Leone, Liberia, Mali, Ivory Coast, Burkina Faso, Ghana, Togo, Benin, Niger, Nigeria, Chad, Cameroon, Central African Republic, Sudan, Ethiopia, Eritrea, Kenya, Uganda, N Democratic Republic of the Congo (Zaire), Zimbabwe USA (introduced to Florida)
Type locality: "ad fluvium Senegal" = Senegal River.
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Physical Description
Morphology
Physical Description
V. exanthematicus has five subspecies (Steele 1996). This is why the measurements and descriptions vary in much of the literature. Varanus exanthematicus is a thick, stockily proportioned monitor. It has wide head, short neck and tail. The tail tapers and has a double toothed crest. Savannah monitors can reach lengths of up to 1.5 meters (Steele 1997). Other sources say they can reach sizes of up to 2 meters (Rogner 1997). Small sub-equal scales cover the cranial region of the animal. The abdominal scale rows number between 60 and 110. The caudal scales of V. exanthematicus are keeled.
Varanus exanthematicus is gray to brown in color. There are rows of circular, dark edged yellow spots across the animal's back. The tail has alternating brown and yellowish rings. The under body and inside of the limbs is a yellowish color. The tongue of V. exanthematicus is snake-like and blue in color (Steele 1996).
Range mass: 1 to 70 kg.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
- Rogner, M. 1997. Lizards vol-2. Malabar Fl: Krieger publishing.
- Steele, R. 1996. Living Dragons. London: Ralph Curtis books.
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Ecology
Habitat
Habitat and Ecology
Systems
- Terrestrial
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Habitat
Varanus exanthematicus occupies a variety of habitats in Africa. Its preferred habitat is the savannah, but they have adapted to other habitats as well. The lizards have adapted to habitats such as rocky dessert type areas, open forests and woodlands. They are not found in the rainforest or deserts (Steele 1996).
Terrestrial Biomes: savanna or grassland ; forest
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Trophic Strategy
Food Habits
In the wild the diet of adult V. exanthematicus consists of small mammals, birds, snakes, toads, lizards, and eggs (Steele 1996). Other source contradict this finding and say that there is no proof that V. exanthematicus eat any type of vertebrate (Bennett 1999). Many adults also consume large quantities of snails. Full grown V. exanthematicus have teeth that are quite blunt to help them crack and eat snails. The jaw has evolved to put maximum leverage at the back of the jaw to crush snail shells (Steele 1996). Adults will also eat carrion if they come across it. Juvenile V. exanthematicus are mainly insectivores because they lack the teeth to eat snails. Savannah monitors have evolved a way to eat poisonous millipedes. The lizard will rub its chin on the millipede for up to fifteen minutes before eating it. It is believed to do this to some how avoid the distasteful fluid that the millipede excretes in it's defense (Steele 1996).
Varanus exanthematicus feeding habits revolve around the weather. They use a feast and fast system. They feast during the wet season when food is plentiful and easy to find. During the dry season they live off the fat reserves they built up over the wet season. The wet season last for about eight months. During this time V. exanthematicus can consume up to one tenth of its own body weight in a single day (Steele 1996).
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Life History and Behavior
Life Expectancy
Lifespan/Longevity
Average lifespan
Status: captivity: 12.7 years.
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Lifespan, longevity, and ageing
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AnAge
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Reproduction
Reproduction
The breeding season for V. exanthematicus is the same as the feasting period. They feast and breed during the wet season (Steele 1996). When a male finds a mate he will follow her around relentlessly, occasionally biting her on the neck and scratching her neck and legs with his claws. Eventually the female allows the two to mate.
The female will dig a nest herself and lay 20 to 50 eggs (Rogner 1997). Other sources say that the female digs nests that are 15-30 cm deep and only lays up to 15 eggs (Bennett 1999). Some females will lay their eggs in termite mounds. The eggs of V. exanthematicus have an unusually high hatch rate of 100 % (Bennett). Incubation of the eggs takes five to six months and the eggs hatch out in March (Rogner 1997). In the sandy farmlands of Ghana it has been reported that up to 55 babies can be found in an area of 150,000m2 during August and September. The juveniles grow the quickest during their first two months (Bennett 1999).
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Conservation
Conservation Status
IUCN Red List Assessment
Red List Category
Red List Criteria
Version
Year Assessed
Assessor/s
Reviewer/s
Contributor/s
Justification
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Conservation Status
Varanus exanthematicus is listed as a threatened species (Quality Design 1998). In Africa it is persecuted for its skin and as a source of food by the natives. The animal is also exported in great numbers for the pet trade.
US Federal List: threatened
IUCN Red List of Threatened Species: least concern
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Trends
Population
Population Trend
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Threats
Threats
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Management
Conservation Actions
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Relevance to Humans and Ecosystems
Benefits
Economic Importance for Humans: Positive
Varanus exanthematicus is very common in the United States in pet store. It is also used in many lizard skin leather products.
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Wikipedia
Savannah monitor
The savanna monitor (Varanus exanthematicus) is a species of monitor lizard native to Africa. The species is known as Bosc's monitor in Europe, since French scientist Louis Bosc first described the species.[1] It belongs to the subgenus Polydaedalus, along with the Nile, the ornate and other monitors.
Contents |
Etymology
The specific name exanthematicus is derived from the Greek word (ɛkˈsænθɪm) : exanthem meaning an eruption or blister of the skin.[2] French botanist and Zoologist Louis Augustin Guillaume Bosc originally described this lizard as Lacerta exanthematica in reference to the large oval scales on the back of the neck.[1]
Description
Bosc's or Savannah Monitor lizards are a stoutly built species with relatively short limbs and toes, and a skull and dentition adapted to feed on hard shelled prey. Maximum size is rarely more than 1m (3 feet) in length, females are considerably smaller. The pattern and coloration of the skin vary according to the local habitat substrate. The body scales are large, usually less than 100 scales around midbody, a partly laterally compressed tail with a double dorsal ridge and a nostril situation equidistant from the eye and the tip of the snout.[3]
Defense
The main predators of Savannah Monitors are snakes, birds and people.[4] It protects itself through camouflage and is much less conspicuous than the sympatric Varanus niloticus.[5] It prefers to flee or play dead when in danger, but if cornered, defends itself with tail lashes and if need be, a powerful, vise-like bite. When confronted by a predator, the monitor sometimes rolls onto its back and grasps a hind leg in its mouth, forming a ring with its body and making itself harder for the animal to swallow whole while playing dead.[6]
Diet
Information about the diet of Varanus exanthematicus in the wild has been recorded in Senegal [7] and Ghana.[8][9] V. exanthematicus feeds almost exclusively on arthropods and molluscs. In Senegal Iulus millipedes were the most common prey of adults, in Ghana small crickets formed the bulk of the diet of animals less than two months old, orthopterans (especially Brachytrupes), scorpions and amphibians were the most common prey of animals 6–7 months old .
Range
Its range extends throughout sub-Saharan Africa from Senegal east to Sudan and south almost to the Congo River and Rift Valley, where they are replaced by Varanus albigularis.[8] V. exanthematicus is primarily a ground-dwelling species that shelters in burrows, although they are sometimes found in bushes or low trees.[3] In the coastal plain of Ghana, V. exanthematicus juveniles are often associated with the burrows of the giant cricket Brachytrupes.[5]
Threats
Varanus exanthematicus is listed as Least Concern by IUCN.[10] The species is hunted for its leather and meat and for the international pet trade. An average of 30,574 live V. exanthematicus were imported into the US each year between 2000 and 2009, total imports of live specimens into the US between 2000 and 2010 was 325,480 animals. During the same period 1,037 skins, shoes and products of the species were imported into the U.S. Trade in live animals come mainly from Ghana (235,903 animals exported between 2000 and 2010), Togo (188,110 animals exported between 2000 and 2010) and Benin (72,964 animals exported between 2000 and 2010). During the same period total worldwide declared exports of skins and products of the species totalled 37,506.[11] However there is substantial undeclared trade in the species from Sudan, Nigeria and elsewhere [10]
Further reading
- Bennett, D. 2000. The density and abundance of juvenile Varanus exanthematicus (Sauria: Varanidae) in the coastal plain of Ghana. Amphibia-Reptilia 21(3): 301–306.
- Bennett, D, and R. Thakoordyal. 2003. The savannah monitor lizard: the truth about Varanus exanthematicus. Viper Press, Glossop. 2003: 1–83.
- 1993. The Savanna Monitor (Varanus exanthematicus) in Africa and in your home. The Iowa Herpetological Society June: 2-4 (Reprinted in International Reptile Breeders Association (IRBA), Monitor 1(2):1 0-12, 1994).
- Bennett, D. & Sweet, S.S. 2010. Varanus exanthematicus. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>.
References
- ^ a b Bosc, Louis. Lacerta exanthematica. Act. Soc. Hist. Nat. Paris 1. p. 25.
- ^ Oxford English Dictionary (1989). Oxford: Clarendon Press.
- ^ a b Bennett, Daniel; Ravi Thakoordyal (2003). The Savannah Monitor, the Truth about Varanus exanthematicus. UK: Viper Press. p. 84. ISBN 0-9526632-9-5.
- ^ Bennett, Daniel; Brian Basuglo (1998). Lacertilia: Varanus exanthematicus. Herpetological Review 29 (4). p. 240.
- ^ a b Bennett, Daniel (2000). "Observations of Bosc's monitor lizard (Varanus exanthematicus in the wild.". Bulletin of Chicago Herp. Society. 35: 177–180.
- ^ Schmidt, K.P. (1919). "Contributions to the herpetology of the Belgium Congo.". Bulletin of the American Museum of Natural History 39: 385–624.
- ^ Cisse, M (1972). "L'alimentaire des Varanides au Senegal". Bulletin L'Institute Fond. Afr. Noire. 34: 503–515.
- ^ a b Bennett, Daniel (2004). "Chapter 5.2: Varanus exanthematicus". In Pianka, Eric R.. Varanoid Lizards of the World. Indiana University Press. pp. 95–103. ISBN 0-253-34366-6.
- ^ Bennett, Daniel (2000). "Preliminary data on the diet of juvenile Varanus exanthematicus in the coastal plain of Ghana.". Herpetological Journal. 10: 75–76.
- ^ a b Bennett, D.; Sweet, S. (2010). "Varanus exanthematicus.". In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. IUCN. http://www.iucnredlist.org/apps/redlist/details/178346/0. Retrieved 5 April 2012.
- ^ "CITES Trade Database". CITES. http://www.unep-wcmc-apps.org/citestrade/novice.cfm?CFID=49683141&CFTOKEN=77487601. Retrieved 5 April 2012.
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