Madagascar tree boa  (Sanzinia madagascariensis)

The Madagascar tree boa is classified as Least Concern (LC) on the IUCN Red List and is listed on Appendix I of CITES (1).

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).

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

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

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).

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).

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).

View information on this species at the UNEP World Conservation Monitoring Centre.

For further information on this species, see:

• Bristol Zoo:
  http://www.bristolzoo.org.uk/madagascan-tree-boa

For more information on conservation in Madagascar, see:

• WWF:
  http://www.worldwildlife.org/what/wherewework/madagascar/