Madagascar and other Islands
Human Settlers Invade Paradise About 500 A.D., immigrant people from Asia, most probably Indonesia or Malaysia, arrived on Madagascar's shores in hand-hewn canoes, bringing domestic animals with them. They began clearing forests and burning them for farmland, and turned lakes and wetlands into rice paddies. Cleared land produced crops for only a few years until the thin soil became sterile. Farmers then moved on to other parts of the forest, in this slash-and-burn agriculture. At some point, African herdsmen colonized the island, bringing zebu cattle, which crowded out wildlife (Tyson 2000). Gradually, abuse of the land eroded the soil in the central highlands to bare earth, pocketed and gouged by deep gullies and cavernous holes. This region had harbored a great variety of lemurs, along with a wealth of birds, reptiles and unique plants. Throughout the island, wildlife declined as habitats disappeared, isolating animals in smaller and smaller patches of forest and wetlands. The large lemurs, tortoises and elephant birds were avidly hunted.
Within 600 years of the arrival of the Malagasy, extinctions claimed many native animals. Several elephant bird species, the larger lemurs and many native plants vanished. Two kinds of pygmy hippos inhabited the island. The Madagascar Hippopotamuses (Hippopotamus lemerlei), an amphibious species, and Hippopotamus madagascariensis, a forest species, were both about 6.5 feet long and 2.5 feet tall, smaller than the Common Hippopotamus of Africa, which is about 10 feet long (Tyson 2000). From genetic and anatomical analysis, both seem to have evolved from the latter species (Tyson 2000). The hippos had been widely distributed and very common prior to the arrival of the Malagasy (Dewar 1984). Their bones have been found with marks indicating that they had been butchered (Tyson 2000). Both died out long before Europeans arrived. The native crocodile, whose large bones have been found, is believed by some scientists to represent large specimens of Nile Crocodiles, the species native today (Tyson 2000). It is thus possible that the crocodile survived. A large mongoose-like viverrid, Cryptoprocta spelea, and a very unusual aardvark-like animal, Plesiorycteropus madagascariensis, died out at an early date (Dewar 1984).
Prior to the arrival of humans, elephant birds had been abundant in most parts of the island, as attested by the prevalence of their bones. There were two genera, and from six to 12 species of these birds (Tyson 2000). It is likely that the flightless birds fell prey to the primitive weapons of the Malagasy and were crowded out of their habitats by livestock (Tyson 2000). The last to die out was the Great Elephant Bird (Aepyornis maximus), which may have survived until recent times by retreating to remote swamps. Dr. Alexander Wetmore of the Smithsonian Institution examined bones of a Great Elephant Bird unearthed in archeological excavations in the 1960s. He was amazed by their size: "The incredible femur, or thighbone, of this ponderous bird is by far the largest I have ever seen" (Wetmore 1967). Estimated to weigh at least 1,000 pounds, more than three times the weight of an Ostrich, it produced eggs larger than any dinosaur's, with a capacity of 2 gallons (equivalent to seven Ostrich eggs), 180 chicken eggs or 12,000 hummingbird eggs (Bradbury 1919, Fuller 1987). When one was X‑rayed, the bones of an embryo three‑fourths developed were revealed (Wetmore 1967). Something had interrupted the embryo's growth and frozen it within the eggshell for hundreds and perhaps thousands of years (Wetmore 1967).
Despite its fearsome size, the Great Elephant Bird lacked a hooked beak for tearing prey and was plainly not a predator (Wetmore 1967). Its large, clawed feet may have helped it defend itself against the small native predators but were not enough to protect it from Malagasy arrows. Its short legs prevented it from running as fast as its relative, the Ostrich, but it may have been quite agile when chased. This vegetarian bird browsed and cropped plants, able to reach with its long neck to the lower branches of trees (Wetmore 1967). By the mid-16th century, when Europeans had managed to establish a foothold in Madagascar, the new French Governor, Sieur Etienne de Flacourt, wrote in 1661 that the Great Elephant Bird was still found in the south of the island, "seeking the most deserted places" to avoid human hunters (Tyson 2000). Villagers of Antandroy told of an Ostrich-like bird that was difficult to catch, according to Flacourt (Tyson 2000).
The exact date this giant bird became extinct is not known with certainty. Alan Feduccia (1996), an eminent paleo-ornithologist, asserts that elephant birds of many species were still widespread in the 10th century but gradually disappeared as a result of human activity. He cites an account by a French merchant sailor in 1848, who visited Madagascar and saw the shell of the Great Elephant Bird; he was told that it belonged to the chief and that the bird that produced such eggs "is still more rarely seen" (Feduccia 1996). Some authorities estimate that it died out in the mid-17th century, although there is no proof that any European ever saw one of these birds (Tyson 2000). It has been suggested that Europeans were responsible for the birdís extinction by hunting and destroying its habitat (Quammen 1996). But Thomas Brooks (2000) of the Center for Applied Biodiversity Science, Conservation International, asserted in a list of extinct birds in Threatened Birds of the World (BI 2000) that all the elephant birds had disappeared by 1500. In a bizarre footnote to this species' epitaph, an Aepyornis egg washed up on Australia's western coast in 1995. No conclusive explanation for this strange event has been put forth, although it is likely that it became unearthed from long interment by rains, and washed out to sea. Much less is known of the other species of elephant birds, which existed in a variety of sizes down to a chicken-sized species.
Lemur-like primates once lived on many continents, but nowhere had they evolved into such a great variety of species. When the Malagasy people arrived some 1,500 years ago, lemurs occupied every habitat, even marshland. A species as tall as a man must have startled the Malagasy immigrants, giving rise to legends that these animals had superhuman powers. The first French naturalists were told by the Malagasy that these primates were thought to be the ghosts of sacred ancestors of man, inspiring the genus name Lemur, the word for ghost in Latin. The Malagasy considered some lemurs sacred and punished anyone who harmed them, but most species were feared as evil demons and were killed on sight.
From their arrival on Madagascar, the Malagasy hunted the larger species of lemurs, almost all of which are now extinct. Archaeological excavations show that they formed a staple in the immigrants' diets. Such diggings have unearthed the skulls and bones of long‑extinct lemurs in early Malagasy jars and kitchen middens; their heads had been split by ax-heads made from an extinct flightless bird (Jolly 1980).
In the centuries following colonization by the Malagasy immigrants, some 15 species of lemurs of eight genera became extinct (Mittermeier 1997). These extinct lemurs were, for the most part, far larger than surviving species and had evolved to fill many ecological niches. Three Megaladapis lemurs weighed between 90 and 170 pounds and moved slowly through the trees, feeding on foliage (Tattersall 1993). Another species, Archaeolemur, was about the size of a female baboon and lived on the ground (Tattersall 1993). Two Palaeopropithecus species weighed between 90 and 130 pounds and were sloth‑like tree dwellers with flexible bodies (Tattersall 1993). These extinct lemurs had evolved many unusual means of movement and locomotion that have no parallels in living species of lemurs.
Largest of all, the massive 400‑pound Archaeoindris was apparently a ground‑dweller, moving on all fours; many of its anatomical characteristics are unlike any living primate (Tattersall 1993). One entire lemur family, Archaeolemuridae, was obliterated. In this family were many species of lemurs weighing between 35 and 55 pounds; they were powerfully built and short‑legged (Tattersall 1993). The heaviest lemur surviving today, the Indri (Indri indri), weighs only about 15 pounds (Tattersall 1993). These lemurs had survived for millions of years, and their extinctions were indeed a major biological loss to the planet. According to primatologists, the surviving lemurs resemble the very earliest primates from the Eocene (Tattersall 1993). Like prosimians in Africa and Asia, but to a far greater degree, lemurs have a highly developed sense of smell. Some species have long, fox-like noses (Preston-Mafham 1991). Genetic analysis of their DNA has revealed that all lemurs are descended from a single ancestor that probably arrived from Africa about 60 million years ago (Garbutt 1999).
The Giant Aye-aye (Daubentonia robusta) lemur was somewhat larger and 2.5 to 5 times heavier than the surviving Aye-aye (see below), but in other respects was very similar (Garbutt 1999). It is known from subfossil remains found in southwestern Madagascar (Nowak 1999). The date of its disappearance is unknown but may be fairly recent.
Archaeologists have uncovered remains of a massive bird of prey, the Malagasy Crowned Eagle (Stephanoaetus mahery), which undoubtedly preyed on lemurs (Feduccia 1996). In fact, at one locality the diet of this eagle, based on the bones of eagles and lemurs found together, contained at least 80 percent primates, including specimens weighing up to 26.5 pounds (Feduccia 1996). Remains of another large eagle of the genus Aquila have been discovered, and it, too, preyed on large lemurs and became extinct after the arrival of the Malagasy. These extinct birds preyed on smaller lemurs as well, including some species still surviving (Feduccia 1996). A bird of prey flying overhead still elicits fear in lemurs, causing them to seek cover. Neither of the two remaining species of eagles on Madagascar preys on lemurs, but two hawk species have been seen preying on young lemurs (Garbutt 1999).
In addition to the Giant Elephant Bird, the large Snail-eating Coua (Coua delalandei), a member of the cuckoo family, became extinct. The last specimen of this large, slate-blue bird was taken on an islet off the east coast, Ile Sainte-Marie, in 1834 (Morris and Hawkins 1998); reports by observers who claimed to have seen the bird were recorded as late as 1930 (Fuller 1987). The causes of this bird's disappearance, and even its exact range, remain obscure (Langrand 1990). Many specimens of this bird were taken before its extinction and kept in museums in Leiden; London; New York; Paris; Philadelphia; Tananarive (Madagascar); and Cambridge (Massachusetts) (Fuller 1987). The long feathers of this bird were highly valued by the Malagasy, and hunting may have reduced its numbers to a critically low level (Fuller 1987). It is also possible that the many birds killed for zoological specimens may have pushed this already rare bird to extinction, since its distribution may have been limited to the tiny Ile Sainte-Marie. No reliable record exists of its presence on the main island of Madagascar, but there is hope that it might be found in lowland forest near the Bay of Antongil (Morris and Hawkins 1998). Ten closely related species of couas survive, all smaller than the Snail-eating Coua.