The "Eighth Continent": Madagascar's unique fauna and flora

However one tries to quantify the biodiversity of a region, Madagascar stands out as one of the biologically richest parts of the world. Though the 1800 years since the arrival of the first human settlers saw the disappearance of 90% of the island's forests, including almost all lowland rainforests that were richest in wildlife, Madagascar today is remarkable for its natural wealth. Some 99 lemur species and subspecies have survived, along with all but one species of tenrec, various mongooses and their relatives, more chameleons than any other country, several hundred kinds of frogs, and thousands of endemic invertebrates and plants. Madagascar's fauna and flora include many extremely unusual and unique examples of evolution. The island is considered one of the five most biologically important areas in the world. According to the International Union for the Conservation of Nature, its primates are the world's highest priority for conservation.

Flora

Madagascar has one of the richest floras in the world. A staggering 80% of its plants are found nowhere else in nature. Conversely, its flowering plants make up 20% of all the plants in the African region. The diversity of endemic plants that survived almost 1800 years of forest destruction continues to astound biologists and conservationists. One mountain chain has 150 endemic vascular plants. They are among the 10,000 or so species of plants native to the island.

Some 2,000 years ago, the Eastern rainforests stretched over a band 100 miles wide from North to South, covering 27 million acres. Though rulers as early as the 18th century's Andrianampoinimerina realized the dangers of deforestation and, accordingly, passed decrees to try to protect the remaining forests, by the late 19th century over half of the island's forests had disappeared. Intensive cutting continued in the 20th Century after the French established their colonial rule. Indeed, prime lowland forests throughout the island and 3/4 of the rainforest were cleared by the colonial authorities to grow coffee and other crops in the first three decades of the century. The rainforest was heavily logged between 1950 and 1985, with about 275,000 acres cleared and burned each year. Today, Masoala National Park in the Northeast still retains sizeable areas of un-logged coastal rainforest, but the Southeastern region of the island is left with mere fragments of the original unbroken expanses. The remnants tend to be on sharp ridges where soil is poor and access difficult. Ranomafana National Park is a prime example, straddling one such escarpment.

The Western dry, deciduous forests lie in the rain shadow of the Eastern mountain ranges, which block a substantial portion of the moist easterly winds, and force much of the remainder to rise and condense most of their humidity in the form of rain around the mountains before this moisture has a chance to travel further West. Many plants have adapted to the dry environment of the deciduous forests of the West. Here, different species of baobabs can be found, as well as large tamarind trees along the rivers. The lovely orange bell flowers of the Ipomoea carnea plant burst into bloom during the short rainy season. These forests are also the home of the Flame Tree (Delonix regia), now grown around the world for its showy cascades of red flowers.

Species from a family of primitive pines known as Podocarps have grown on the island since the days of the dinosaurs. The family is represented by species in other regions of the world that were part of Gondwana, from South America West to Southeast Asia. Madagascar has a number of native Podocarps, of which four endemic species or varieties are listed on the IUCN Red List of Threatened Plants as either Vulnerable or Rare. At least 26 genera of plants are native to Madagascar and South America but not to Africa, and are believed to be remnants from Gondwana. Another one of these, Madagascar's national tree, the Traveler's Tree (Ravenala madagascariensis), is a palm-like species of the bird-of-paradise family. Its closest relative in the same genus grows in Brazil and Guyana, but not in Africa. This tree has leathery petals covering its pollen and nectar, and is a key food source for bats as well as lemurs. In return, it depends on lemurs for pollination. Lemurs feed on the nectar, getting their noses covered with pollen in the process. They are so fond of the nectar that they travel miles to find another Traveler's Tree, still carrying the nectar on their noses and, unknowingly, pollinate the next tree they feed on.

A plant of the Winteraceae family that has been growing on the island for 30 million years was recently seen again after a period of 90 years during which it was thought extinct. This tree, Takhtajania perrieri, has many primitive features, such as a lack of vessels to move water and minerals; like many of Madagascar's relict species, it once grew on much of continental Africa, though it has long been extinct there.

Madagascar has more palm species than all of Africa. Many are on the IUCN Red List in various threat categories. The "ravimbe" Big-leaf Palm (Marojeya darianii) was singled out by the Species Survival Committee of the IUCN as one of the 12 most critically endangered living organisms in the world. This species was only discovered in 1982 by Dr. Mardy Darian of San Diego, a veterinarian by training and a world-class botanist. It is found only in a handful of sites in Masoala. The majority of palms grow in the Eastern rainforests in a great diversity of sizes. Two threatened palms, Dypsis hildebrandtii and Dypsis louvelii, are miniature delicate-fronded palms only 3 feet high. Others, like the threatened Ravenea glauca, are majestic giants with long, straight trunks rising 50 feet or more to a luxuriant crown.

On the entire continent of Africa, only one species of baobab tree is native, while seven species are found in Madagascar. These strange-looking trees have wide trunks that taper to a narrow crown, looking like upside-down trees with their roots up in the air. Some baobabs grow to immense size. One famous specimen measures 46 feet around the base of the trunk. Baobabs are extremely important to both wildlife and humans. In the West and South, villagers cut holes in their massive trunks and hollow out the spongy pith where water accumulates. These trees become wells, and villagers set ladders against the trunks, climb to the hole cut from the trunk, and lower buckets into the pool of water. Natural holes in baobab trunks and branches provide important nesting holes for birds and lemurs. These trees are fire-resistant, and fortunately, they are worthless as timber because of their soft, pulpy cores. For this reason some stands of thousands of huge, very old baobabs remain in parts of the island.

One very strange group of Malagasy plants native to dry areas has nine species in the same genus, Pachypodium. These succulent plants lose their leaves at the onset of the dry season and have evolved into a variety of forms, all with gray, smooth bark. Eight of the nine species are threatened with extinction, according to the IUCN. One of these, the endangered Pachypodium decaryi, is native to the "tsingy" limestone crags of the Northwest. Its smooth, silvery trunk resembles a large inverted turnip, fat at the base and tapering upward, topped by a messy mop of thin, straggly branches . It bears large, white flowers during the dry season. Its main population occurs in the Ankarana Special Reserve, where burning is banned. Other Pachypodiums have equally bizarre shapes, including the bulbous Pachypodium rosulatum, which resembles a huge gourd sprouting long, thin shafts from which its bright yellow flower blooms. The rare Pachypodium densiflorum, with the appearance of a domestic jade plant run amok, has a mass of short, gray branches sprouting from a squat gray base. All these plants are highly susceptible to fire. Another threat to Pachypodia consists of collectors who tear specimens, especially unusual forms, from mountain slopes. Without a strong conservation program, these fascinating plants could easily disappear.

Other strange trees of the Southern "spiny thicket" include the Octopus Tree (Didierea madagascariensis), a member of an endemic family of 11 cactus-like species, the Didiereaceae. This tree has no trunk, but a bouquet-like grouping of stems covered in long, needle-sharp spines that branch out in odd, twisted shapes. Although resembling cacti, this family has no close relatives anywhere in the world. Another member of the family, Allaudia procera, has a thick trunk with very long spines that grow in rows curving upward, with small, rounded leaves along its branches. In spite of the numerous sharp spines, several lemur species are able to leap onto these plants without hurting themselves.

The discovery of the medicinal effects of the endemic Madagascar Periwinkle (Catharanthus roseus) has saved thousands of human lives. Two potent alkaloid compounds found in this plant have proven highly effective in the treatment of acute lymphocytic leukemia. The Madagascar Periwinkle is easy to propagate, and is now grown in greenhouses around the world. Ongoing research is uncovering other Malagasy plants of medicinal value. More than 50 species of wild coffee grow in the island's eastern rainforests, providing an important genetic base for hybridizing with other strains because of their insect-resistance and low level of caffeine.

Lemurs

The world-renowned lemurs of Madagascar are the focus of many conservation programs. New species continue to be discovered, most recently in 2008, with a new species that is very small in size, Macarthur's mouse lemur, discovered by local scientists inventorying the tropical rainforests of Makira, a newly protected area in Northeastern Madagascar near Masoala National Park.

The most gregarious of the lemurs are the Ring-tailed Lemurs (Lemur catta), known as "maki" in Malagasy, who travel about in boisterous, friendly troops, living mainly on the ground. These lemurs have long, fox-like muzzles, large, soft golden-brown eyes, fluffy, gray fur, and black-and-white ringed tails. They live in matriarchal clans of up to 25 individuals. The maki use their boldly patterned tails in a complex language of visual and scent signals. They wave them about to show dominance, as a signal to follow other group members, or rub them on their wrist glands to wave at their rivals in territorial battles. Ring-tailed Lemurs communicate with one another in a variety of sounds, from soft mewing contact calls, to clucking alarm sounds to a territorial "bark-howl".

One of the strangest mammals in the world is the Aye-aye (Daubentonia madagascariensis), so unique that it has been assigned its own family, Daubentoniidae. When first discovered, scientists classified it as a squirrel because of its long, bushy tail and short legged body. Spending the day in their twig and leaf nests, Aye-ayes emerge at night to forage for insects and fruit. The Aye-aye's enormous ears are sensitive to the movements of insects under tree bark. The aye-aye uses its long and skeletally thin middle finger to tap on wood, listening for the movement of insect grubs under the bark. It then extract the grubs with its middle finger. The aye-aye thus fills the ecological role of a woodpecker. Aye-ayes eat fruit as well, biting holes into the hard shells of coconuts and scraping the meat out with their middle fingers. They have also been seen eating nuts of a native tree, nectar from the Traveler's Tree, fungus and lychee nuts. Aye-ayes were considered among the most endangered animals in the world, facing imminent extinction. Since the early 1980s, field surveys have revealed that Aye-ayes actually have a larger distribution than was originally thought. And while once thought solitary, groups of three to four individuals have been seen traveling together and feeding at foraging sites.

One lemur has recently been rediscovered in the wild and, in the process, an entirely new species was found. The Greater Bamboo Lemur (Hapalemur simus) seemed to have disappeared in the wild some time in the mid-19th century. Not until 1964 was this 5-pound, grizzled, gray-olive lemur seen again in a village market, where it was purchased by a French scientist. Unfortunately, it escaped. A pair captured in 1972 in a Southeastern rainforest lived in the Tsimbazaza zoo in Antananarivo, until both male and female and their two offspring died. Patricia Wright, an American primatologist, decided to search for this species in 1986 in its supposed range. Fossil evidence indicates that 1,000 years ago, the Greater Bamboo Lemur was widely distributed throughout most of Madagascar's forests, and European naturalists saw it fairly regularly in the 19th century. When she saw a russet-colored lemur clinging to a trunk, making loud "tonking" calls, Wright assumed that she had rediscovered the Greater Bamboo Lemur. Although a different color, she concluded that these animals probably represented a color variation. A German primatologist, Bernhard Meier, made independent studies in this patch of rainforest at the same time, also discovering the reddish-gold lemur. Both scientists had great difficulty making observations because of its extreme shyness. Finally, one was caught, and in 1987, after chromosomal and anatomical studies were done in France, this lemur was found to be an entirely new species. It was named the Golden Bamboo Lemur (Hapalemur aureus).

Sifakas (the Propithecus genus) are the most acrobatic lemurs, leaping from tree to tree, but they have a unique means of locomotion to cross open ground between trees. Standing on their long legs, they hop sideways, holding their forelimbs up for balance, in an awkwardly graceful dance-like gait. Different species live in different habitats around the island, from the rainforest-dwelling "simpona" Silky Sifaka and the "sadabe" Diademed Sifaka to Decken's Sifaka of the dry deciduous forests of the West and Verreaux's Sifaka in the spiny thicket and dry forests of the South. Along with the Diademed Sifaka, the "babakoto" Indri is the largest lemur still in existence. It has a head-body length of up to two-and-a-half feet, reaching nearly 4 feet with the legs fully extended. It has a rudimentary tail, and silky fur that varies from black with large white patches along the limbs, neck, crown and lower back, to entirely black (especially in the Northern populations in and around Anjanaharibe-Atsimo Special Reserve near Marojejy National Park). The babakoto practice long-term monogamy, seeking a new partner only after the death of a mate. They live in small families consisting of the mated male and female and their maturing offspring. They reach reproductive maturity between seven and nine years of age, enjoying a relatively long childhood. Best known for their loud, distinctive songs, which can last several minutes, babakoto typically sing sequentially, different groups responding to one another through the forest. In addition to solidifying contacts between groups, the songs may communicate territorial defense and boundaries, environmental conditions, reproductive potential of the group members, and warning signals. The babakoto may sing after disturbances such as thunder, airplanes, bird calls, and other lemur calls. Their peak singing hours are between 7 and 11 AM. Daily frequency of song is highest in November and December (near the breeding season), when the babakoto can sometimes even be heard during the night. Several other babakoto vocalizations have been identified, including the "roar", the "hoot", the "honk", the "grunt", the "kiss", the "wheeze", and the "hum", though their meaning is still not clear to humans. The babkoto has a peculiar, human-like behavior in the sun. Like its sifaka relatives, and other lemurs such as the maki, it frequently engages in what has been described as sun-bathing or sun-worshipping. As the sun rises each morning, it will sit and face it from a tree branch with its legs crossed, back straight, hands low with palms facing out or resting on its knees, and eyes half-closed. Biologists are hesitant to call this behavior sun worship, as the term may be overly anthropomorphic.

Masoala Peninsula in the Northeast is the last refuge of the Red Ruffed Lemur (Varecia rubra), a 9-pound, reddish species that is now recognized as distinct from the Black-and-White Ruffed Lemur (Varecia variegata), which has a wider range within the Eastern Rainforest. It is a large lemur, some reaching a size comparable to that of the babakoto and sadabe. Unlike all other diurnal primates, females build nests 10 to 20 meters above the forest floor, using twigs, leaves, vines, and fur. Known for their loud, raucous calls, the Red Ruffed Lemur and Black-and-White Ruffed Lemur understand each other's calls, despite living in different parts of Madagascar, as the research at the Duke University Primate Center has demonstrated.

Mouse lemurs are nocturnal lemurs of the genus Microcebus. They have a combined head, body and tail length of less than one foot. Goodman's Mouse Lemur (Microcebus lehilahytsara) is a species from the Eastern rainforest, discovered only in 2005 by renowned primatologist Steve Goodman, as reflected by its English and scientific names ("lehilahy" means man and "tsara" means good in Malagasy). Though still largely a mystery to scientists, this species' mating season is particularly long, typically lasting from August to January. After a gestation period of two to three months, the female gives birth to one or two babies at a time. Berthe's Mouse Lemur (Microcebus berthae) is the smallest primate in the world. Its average body length is less than four inches. It lives in a small area in the West of the island.

Fossa and relatives

The fossa (Cryptoprocta ferox) is an endemic mammal that is closely related to the mongoose. It is the largest mammalian carnivore on the island (the largest carnivore on Madagascar is the Nile crocodile). Though most still classify and accept the fossa as part of the family of viverrids, some have recently reclassified it in a new family of Malagasy civets and mongooses, the Eupleridae. The fossa is a carnivore, active during the day and night. It is particularly adept at hunting lemurs, and is the main predator of many species. Prey may be obtained by hunting either on the ground or in the trees. During the non-breeding season, fossas hunt individually, but during the breeding season hunting parties may be seen, and these may be pairs or mothers and young. One member of the group scales the tree and chases the lemurs from tree to tree, forcing them down to the ground where the other is easily able to capture them. The fossa has no natural predators. Pioneering research by field biologist Luke Dollar established that there are fewer than 2,500 mature individuals surviving in fragmented areas in continuing decline.

The falanouc and fanaloka are the other members of the family of Malagasy euplerids. Small (less than 2 feet long) and shy, the falanouc most closely resembles the mongooses, with its long snout and low, plain brown body. The fanaloka (Fossa fossana) has dark horizontal stripes running from head to tail, where the stripes become vertical, wrapping around the bushier tail. Somewhat smaller in size, the Ring-tailed Mongoose (Galidia elegans) has a long and slender body, with a rounded head and a pointy snout. Its fur is a dark red color with black feet and a bushy tail covered with black and red rings.

Chameleons, Geckos and Frogs

Madagascar is home to about half of the world's species of Chameleons. These reptiles are distinguished by their separately mobile and stereoscopic eyes, their very long, highly modified, and rapidly extrudable tongues and their back-and-forth swaying gait. Many species also possess a prehensile tail, crests or horns on their distinctively shaped heads, and/or the famous ability to change color. They vary greatly in size, their total length ranging from just over an inch for the tiny Brookesia minima, the world's smallest reptile, to over two feet for the male Furcifer oustaleti.

Chameleons' eyes are the most distinctive among the reptiles. The upper and lower eyelids are joined, with only a pinhole large enough for the pupil to see through. They can rotate and focus separately to observe two different objects simultaneously. This effectively gives them a full 360-degree arc of vision around their body. When prey is located, both eyes can be focused in the same direction, giving sharp stereoscopic vision and depth perception.

Chameleons have very long tongues (sometimes longer than their own body length) which they are capable of rapidly extending out of the mouth. The tongue extends out faster than human eyes can follow, at around 26 body lengths per second. The tongue hits the prey in about 30 thousandths of a second. A bone at the base of the tongue is shot forward to give the tongue the initial momentum it needs to reach the target. A muscular, club-like structure at the tip of the tongue, covered in thick mucus, forms a suction cup. Once the tip sticks to part of the prey, it is drawn quickly back into the mouth, where the chameleon's strong jaws crush the prey. Even a small chameleon is capable of eating a large locust or mantis.

Several chameleon species are able to change their skin colors. Some, such as the Smith's dwarf chameleon, use this ability to blend in with their surroundings, as an effective form of camouflage. Color change is also used as an expression of the physiological condition of the lizard, and as a social indicator to other chameleons. Research suggests that social signaling was the primary driving force behind the evolution of color change, and that camouflage evolved as a secondary advantage. Color change is accomplished using specialized cells that lie in three layers under their transparent outer skin. Cells in the upper layer contain yellow and red pigments while cells below these are colorless and reflect, among others, the blue part of incident light. A third layer of dark melanin-containing cells influences the 'lightness' of the reflected light. All these cells can rapidly relocate the pigments in their cytoplasm, thereby controlling the color of the chameleon.

Uniquely adapted for climbing and visual hunting, Chameleons now inhabit rain forests, savannas and semi-arid regions around the island. They are mostly found in trees or occasionally on smaller bushes, though some smaller species live on the ground under foliage.

Geckos are widespread in Madagascar. These small to moderately large lizards exist in a diverse array of forms across the island, from the neon-colored day geckos to the Uroplatus geckos (also known as leaf-tailed or fringed geckos), masters of camouflage with skin color and color patterns that almost perfectly match tree bark or moss.

Leaf-tailed Geckos, forming the Uroplatus genus, live in the rain forests of the island, and are found nowhere else on Earth. They are nocturnal, and range in length from about 12 inches (U. giganteus) to 4 (U. ebenaui). The larger leaf-tailed geckos spend most of the daylight hours resting vertically, head down, on tree trunks, where they literally "blend into the woodwork", while the two smaller leaf-tailed geckos (U. phantasticus and U. ebenaui) spend more time in ficus bushes, where they are very difficult to distinguish from the twigs and leaves. The bark-mimicking species have developed a flap of skin known as a dermal flap and running the length of their bodies, which they lay against the tree as they rest during the day, and where it scatters shadows and makes their outline practically invisible. In the breeding season, female Uroplatus lay between two and four eggs each. Habitat destruction and illegal wildlife trade are the main threats to the future of these geckos

Madagascar also has several native species of day geckos, forming the genus Phelsuma. Standing's Day Gecko (Phelsuma standingi), for example, is native to the spiny forests of the south and is one of the most coveted by collectors. They have specialized toe pads that enable them to climb smooth vertical surfaces. In the past few years, day geckos have become familiar to American TV viewers as the advertising icon for the insurance company GEICO, whose advertisements feature an animated anthropomorphic Phelsuma gecko that speaks with a British accent.

Over 200 species of frogs have been named and described. All but two are endemic. The majority are native to rainforest environments. In one such area, a montane rainforest in the Andasibe region, 90 species are native, the highest diversity of frogs in the world. A candidate for the world's smallest frog - and perhaps the world's smallest vertebrate - is a minute frog, Stumpffia pygmaea, which measures less than 3 millimeters in length (about one tenth of an inch). Perhaps the most spectacular Malagasy frog is the bright red Tomato Frog (Dyscophus antongili), which secretes poisonous white mucous when threatened. Fat and squat, this toad-like frog is large enough to cover the palm of a hand. The Boophis genus has several brightly colorful species, as does the Mantella genus, including the aptly-named Golden Mantella.

Birds

Madagascar has five endemic families of birds:

• the Vangas (except for the Comoro Blue Vanga, which is found only in the Comoro Islands), a family of about 20 species of passerine birds who build their stick nests in trees and do not migrate;
• the Couas, technically a sub-family of the cuckoo family, mostly terrestrial birds featuring brightly-colored fleshy areas around the eyes; four species occur in rainforests and another six are found in the dry forests of the West and the spiny thicket of the South;
• the Ground-rollers, related to the kingfishers and rollers, most with striped or flecked plumage; They nest as solitary pairs in holes in the ground which they excavate themselves;
• the Mesites, near-flightless birds with a somewhat pheasant-like appearance, living in forest and scrub;
• the Asities, technically a sub-family of the broadbills, mostly small forest birds with sexually dichromatic plumage and brightly colored wattles around the eyes of the males; these wattles, which are most conspicuous during the breeding season, get their color from arrays of collagen fibers, a method of pigmentation that is unique in the animal kingdom; they possess twelve tail feathers on extremely short tails, and they have forked tongues adapted to the extraction of nectar;
• the Cuckoo-roller (also found in the Comoro Islands), a family onto itself, and also known in English by its French name, courol; with a total length of up to 20 inches, the Cuckoo-roller is sexually dichromatic, with the male distinguished by a velvety gray chest and head, a dark iridescent green back and tail, and black crown and eye-stripe, while the female is mostly brown with strongly dark-spotted pale underparts;

Many more species are endemic to the island. Some of the more notable include the Madagascar Pochard, the Madagascar Fish Eagle, the Madagascar Serpent Eagle, the Madagascar Red Owl, the Madagascar Green Pigeon, the Madagascar Blue Pigeon, Appert's Greenbul, the Madagascar Fody, the Madagascar Magpie-robin, the Greater Vasa Parrot and the Lesser Vasa Parrot (also found in the Comoros), the Madagascar Coucal (also found in Aldabra), the Madagascar Paradise Flycatcher (also found in the Comoros), the Crested Drongo (also found in one of the Comoros), and the Madagascar Pygmy-Kingfisher,

The fauna and flora of Madagascar have far too many species to list, let alone describe with any detail. For more information, please try the relevant links on our links page.