Animals of Madagascar & the Indian Ocean islands in U.S. zoos

An island that evolved on its own

About 135 million years ago, the breakup of Gondwana split a landmass made of Madagascar, Antarctica and India away from Africa and South America. Madagascar then separated from India about 88 million years ago. Since then its plants and animals have evolved in relative isolation, which is why some ecologists call it the "eighth continent" and why Conservation International counts it as a biodiversity hotspot.

Many groups common on the African mainland never arrived. All of the island's native land mammals that cannot fly descend from ancestors that crossed the sea by rafting or swimming, likely helped by currents. With no monkeys to compete with, lemurs spread into almost every habitat and split into more than 100 species. The ring-tailed lemur is the living lemur best adapted to moving on the ground, while Coquerel's sifaka can leap up to 11 m (35 ft) between trees.

The nearby islands of the western Indian Ocean have their own animals. The Aldabra tortoise is native to Aldabra atoll and other islands of the Seychelles, and the Rodrigues flying fox lives only on Rodrigues, a small island belonging to Mauritius. The mongoose lemur is one of only two lemur species found outside Madagascar, on the Comoro Islands of Mohéli and Anjouan, where it was introduced.

Lookalikes that are something else

Isolation produced animals that resemble mainland species without being related to them. The fossa looks like a small cougar, but it belongs to Eupleridae, a family made up entirely of Madagascar's native carnivores, all descended from one ancestor. It climbs head-first down tree trunks on unusually flexible ankles. The lesser hedgehog tenrec is covered in spines like a hedgehog, yet it sits in an entirely different family, Tenrecidae.

Reptiles and invertebrates are just as distinctive. More than 90 percent of the island's reptiles are endemic, and two-thirds of the world's chameleon species live there. Henkel's leaf-tailed gecko has a flattened tail that gives its genus, Uroplatus, its name, and the wingless Madagascar hissing cockroach defends itself by forcing air out through breathing holes to hiss.

Rainforest, dry forest and spiny forest

The humid east was once covered in rainforest. The red ruffed lemur lives only in the rainforests of the Masoala Peninsula in the northeast. The west holds dry deciduous forest with baobabs and tamarinds, home to Coquerel's sifaka in the northwest, and the southwest has spiny forest found nowhere else. The radiated tortoise grazes the dry brush and thorn forest of the south, and the Madagascar teal depends on mangroves along the west coast. Grassland now dominates the central plateau, which was once largely forested.

Forest loss and hunting

Since people arrived about 2,350 years ago, Madagascar has lost more than 90 percent of its original forest. Slash-and-burn farming known as tavy, larger cattle herds, charcoal for cooking and coffee growing all played a part. Illegal logging of precious woods inside protected forests continues. Rosewood logging has intensified since 2009 and has eaten into the red ruffed lemur's small range.

Hunting and trade add to the damage. Elephant birds and numerous giant lemurs vanished after humans arrived. A 2012 assessment found 90 percent of lemur species threatened, the highest share of any mammal group. The radiated tortoise is Critically Endangered, and in 2018 more than 10,000 of these tortoises were found in a single house in Toliara. Several of these animals are managed in zoos through Species Survival Plan breeding programs, including the red ruffed lemur and the radiated tortoise. Their wild status is tracked on the IUCN Red List.