Overview

Brief Summary

Biology

Whilst known as a 'tree boa', this snake is less arboreal than other tree boas, using trees only when hunting. It is a nocturnal snake, feeding on small mammals and birds, seeking them out using the heat-sensitive pits around its mouth that enable it to hunt for warm-blooded prey in complete darkness. The victims, once captured, are constricted by the powerful coils of the boa which tighten as the prey struggles, restricting the blood flow to the heart and ultimately causing circulatory failure. Boas are not venomous. Boas all give birth to live young - the Madagascar tree boa usually gives birth to fewer than 12 offspring at a time. Pregnancy lasts for six months and the young emerge at just 25 cm long and are red in colour. They attain their adult colours gradually throughout their first year of life (2).
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Description

This medium-sized constrictor occurs in two colour variations. Prevalent mainly in the eastern half of the range is the green to greyish-green form which tends to be about two thirds of the size of the mandarin form which is yellow, orange and brown and occurs in some parts of the western side of the range (2) (4). As with many boa species, there are heat-sensitive pits around the mouth, used for hunting at night (2).
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Distribution

Continent: Indian-Ocean
Distribution: Madagascar, Nossi Be = Nosy Bé  madagascariensis: E Madagascar volontany: W Madagascar  
Type locality: Madagascar
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Range

The Madagascar tree boa occurs throughout the island of Madagascar except for the most south-westerly corner (4).
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Physical Description

Type Information

Syntype for Sanzinia madagascariensis
Catalog Number: USNM 10982
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: No Further Locality Data, Madagascar, Africa
  • Syntype: Duméril, A. & Bibron, G. . Erpétologie Générale ou Histoire Naturelle complète des Reptiles. 6: 549.
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Ecology

Habitat

This boa lives in Madagascan forests, from lowland tropical forests and dry forests to humid upland forests (2).
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Life History and Behavior

Life Expectancy

Lifespan, longevity, and ageing

Maximum longevity: 21.8 years (captivity)
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Conservation

Conservation Status

Status

The Madagascar tree boa is classified as Vulnerable (VU A1cd) on the IUCN Red List 2003 (1) and is listed on Appendix I of CITES (3).
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Threats

Habitat loss through deforestation for human settlement and agricultural practices has meant that the Madagascar tree boa is restricted to the remaining protected areas of Madagascar (2). This amounts to just 10 – 20 % of the original primary forest on the Island (5).
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Management

Conservation

The Madagascar tree boa is part of a captive breeding programme, but the only sure way to ensure its survival is to protect the remaining habitat in Madagascar by implementing sustainable forestry. In September 2003, the president of Madagascar agreed to triple the amount of land under protection from 15,000 km² to 50,000 km² within five years (5).
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Wikipedia

Sanzinia madagascariensis

Sanzinia madagascariensis (also known as the Malagasy tree boa,[4] or Madagascar tree boa) is a non-venomous boa species endemic to the island of Madagascar. Two subspecies are currently recognized: S. m. madagascariensis and S. m. volontany.[3]

Description[edit]

Sanzinia madagascariensis

Adults average 4–5 feet (122–152 cm) in length, although 6–7 foot (183–213 cm) specimens are not uncommon. Thermoreceptive pits are located between the labial scales.[4] Females are larger than males.

Subspecies[edit]

There are two known subspecies:

Sanzinia madagascariensis madagascariensis is greenish in colour and is found on the east side of Madagascar, while S. madagascariensis volontany is brownish in colour and is found on the western side of the island. The separation of these subspecies has been supported on the basis of genetic data, and they may represent distinct species.[5]

Geographic range[edit]

Endemic to Madagascar. The type locality given is "Madagascar".[2]

Habitat[edit]

Favors trees and shrubs near streams, rivers, ponds and swamps.[4]

Conservation status[edit]

This species was classified as Vulnerable (VU) on the IUCN Red List of Threatened Species in 2006[1] with the following criteria: A1cd (v2.3, 1994). This means that a population reduction of at least 20% has been observed, estimated, inferred or suspected over the last 10 years or three generations, whichever is the longer, based on a decline in area of occupancy, extent of occurrence and/or quality of habitat, and based on actual or potential levels of exploitation.[6] It is now listed as Least Concern (LC) as it is widespread, present in heavily degraded habitats and it is not subject to any known or suspected threats.[1]

Also listed as CITES Appendix I, which means that it is threatened with extinction and CITES prohibits international trade except when the purpose of the import is not commercial, for example for scientific research.[7]

Feeding[edit]

Arboreal and generally nocturnal, S. madagascariensis feeds on mammals and birds. Its thermoreceptive pits help it to locate its prey. It will also leave the trees to actively hunt for small mammals on the ground.[4]

Reproduction[edit]

Ovoviviparous, females give birth to up to 12 young at a time, each about 15 inches (38 cm) in length.[4]

When females become gravid, their skin color darkens. This adaptation provides increased heat absorption for the developing young. After giving birth, the color returns normal as soon as it next sheds its skin. Neonates are a bright red that may warn predators to "stay away", while simultaneously providing camouflage among brightly colored treetop flowers.

Taxonomy[edit]

When Kluge (1991) moved Sanzinia madagascariensis (A.M.C. Duméril & Bibron, 1844) to Boa together with Acrantophis madagascariensis (A.M.C. Duméril & Bibron, 1844), it resulted in homonymy. To fix this nomenclatural problem, he proposed the specific name manditra as a replacement for S. madagascariensis.[2]

It has since been shown that the Malagasy boids and the genus Boa do not form a monophyletic group,[8][9][10] so that the lumping of Sanzinia, Acrantophis and Boa was incorrect, and the name Sanzinia madagascariensis is therefore the correct name for this species.

References[edit]

  1. ^ a b c Vences, M., Raxworthy, C.J., Rakotondravony, H. & Rafanomezantsoa, J. (2011). "Sanzinia madagascariensis". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 4 March 2014. 
  2. ^ a b c McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
  3. ^ a b Sanzinia at the Reptarium.cz Reptile Database
  4. ^ a b c d e Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X.
  5. ^ Glaw, Frank; Vences, Miguel (2007). A Field Guide to Amphibians and Reptiles of Madagascar 3rd edition. Köln: M. Vences & F. Glaw Verlags GbR. ISBN 978-3-929449-03-7. 
  6. ^ 1994 Categories & Criteria (version 2.3) at the IUCN Red List. Accessed 10 July 2008.
  7. ^ Sanzinia madagascariensis at CITES and United Nations Environment Programme / World Conservation Monitoring Centre. Accessed 10 July 2008.
  8. ^ Vences, Miguel; Glaw, F.; Kosuch, J.; Boehme, W.; Veith, M. (2001). "Phylogeny of South American and Malagasy boine snakes: Molecular evidence for the validity of Sanzinia and Acrantophis and biogeographic implications". Copeia 2001 (4): 1151–1154. doi:10.1643/0045-8511(2001)001[1151:posaam]2.0.co;2. 
  9. ^ Noonan, Brice; Chippindale, P. (2006). "Dispersal and vicariance: The complex evolutionary history of boid snakes". Molecular Phylogenetics and Evolution 40: 347–358. doi:10.1016/j.ympev.2006.03.010. 
  10. ^ Reynolds, R.G.; Niemiller, M.L.; Revell, L.J. (2014). "Toward a Tree-of-Life for the boas and pythons: Multilocus species-level phylogeny with unprecedented taxon sampling". Molecular Phylogenetics and Evolution 71: 201–213. doi:10.1016/j.ympev.2013.11.011. PMID 24315866. 

Further reading[edit]

  • Boulenger GA. 1893. Catalogue of the Snakes in the British Museum (Natural History). Volume I., Containing the Families ... , Boidæ, ... London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiii + 448 pp. + Plates I-XXVIII. (Corallus madagascariensis, 103-104).
  • Duméril A-M-C, Bibron G. 1844. Erpétologie générale ou Histoire naturelle complète des Reptiles, Tome sixième. Paris: Roret. xii + 609 pp. (Xiphosoma madagascariense, pp. 549-552).
  • Gray JE. 1849. Catalogue of the Specimens of Snakes in the British Museum. London: Trustees of the British Museum. (Edward Newman, printer). xv + 125 pp. (Sanzinia madagascariensis, p. 99).
  • Kluge AG. 1991. Boine Snake Phylogeny and Research Cycles. Misc. Pub. Museum of Zoology, Univ. of Michigan No. 178. 58 pp. PDF at University of Michigan Library. Accessed 11 July 2008.
  • Vences M, Glaw F, Kosuch J, Böhme W, Veith M. 2001. Phylogeny of South American and Malagasy Boine Snakes: Molecular Evidence for the Validity of Sanzinia and Acrantophis and Biogeographic Implications. Copeia No 4. p. 1151-1154. PDF at Miguel Vences. Accessed 29 August 2008.
  • Vences M, Glaw F. 2003. Phylogeography, systematics and conservation status of boid snakes from Madagascar (Sanzinia and Acrantophis). Salamandra, Reinbach, 39(3/4): p. 181-206. PDF at Miguel Vences. Accessed 29 August 2008.
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