Species Fact Profile: Radiated Tortoise (Astrochelys radiata)

Radiated Tortoise

Astrochelys radiata (Shaw, 1802)

Range: Southwestern Madagascar
Habitat: Dry Woodlands
Diet: Grasses, Fruits, Succulents, Carrion
Social Grouping: Solitary/Loose Groups.  Males may become territorial during breeding season
Reproduction: Sexually mature at about 20 years old.  Mate after the rains, nest September through March.  May breed more than once per year.  Clutches of 8-22 eggs laid in a hole 15-20 centimeters deep, then left alone.  The young hatch after an incubation period of 5-8 months
Lifespan:  40-50 Years, Records of 100 Years +
Conservation Status: IUCN Critically Endangered, CITES Appendix I

• Shell length up to 40 centimeters, weight up to 16 kilograms.  Typical tortoise build - high, domed shell, small head, elephantine legs.  Males have longer tails and a more pronounced notch around the tail on the plastron (bottom shell)
• Skin is yellow, except for a blackish patch on the top of the head.  The shell is black, with each scute (shell scale) having a starburst of yellow lines radiating out from the center.  In some specimens the shell may appear to be predominately yellow, in others, it may be blacker
• Typically feed during the mornings, then retreat under bushes during the hottest part of the day, where the patterning of their shells provide camouflage 
• Traditionally, the were considered fady (taboo) by the local people and were left in peace.  In recent years, southwestern Madagascar has seen an influx of migrants from other regions of the country, which do not share these cultural prohibitions against poaching this species
• Decline is partially caused by habitat loss, but most important threat is collection, both for local consumption and for sale on the international market.  Legally protected in Madagascar, but poaching is still a major problem
• Local people sometimes collect tortoises to house with their chickens and ducks, citing a traditional belief that the tortoises can fend off poultry diseases
• Rehabilitation centers exist to return confiscated tortoises back into the wild; the zoo-based population is thriving, with potential animals for reintroduction should that option prove necessary in the future

Zookeeper's Journal: Along with its distant Asian cousins, the star tortoises, the radiated tortoise is often considered the world's most beautiful tortoise.  This has led to a considerable amount of wildlife trafficking, which has also helped make it one of the world's most endangered tortoises.  At one private zoo where I worked, the owner was fanatical about us locking up his radiated tortoises, which spent the day grazing in a paddock, every night in a secure building, counting and double-counting them before we turned off the lights.  (Side note: one of my favorite jobs there was rubbing the shells of the tortoises with mineral oil once a month - it was good for the shell's health, but mostly I just loved how the patterns shined and glowed so brilliantly after I was done).  His fears of theft were that severe.  I can't say they were exaggerated (though I would have loved to see someone try to sneak out of the gate with a bowling-ball sized reptile hidden under their shirt).  Recently, we heard the tragic tale of 10,000 tortoises that were confiscated in one sting - the number that wildlife authorities miss must be equally staggering.  Zoos are active in the conservation of this species, not only through captive-breeding, but through the support of rescue and rehab centers within Madagascar.  Hopefully the situation will improve in the future and this species can be restored to the Malagasy dry forests where they belong.