Madagascar and the Indian Ocean Islands

The island of Madagascar, at approximately 590 000 km² the fourth largest on Earth, has long been recognized as one of the world's highest priority hotspots and one of the top megadiversity countries. Although located only about 400 km from the east coast of Africa, the island, another chip off the supercontinent Gondwana, has been isolated from other landmasses for more than 160 million years. Consequently, most of the plant and animal species occurring there have evolved in long isolation, and are unique and found nowhere else. Levels of endemism in most groups of organisms are exceptionally high, not just at the species level, but often at the generic and even the family levels as well.

In addition to Madagascar itself, we include in this hotspot the neighboring western Indian Ocean Islands which, although much smaller, are also very important biologically. These include the independent nations of Seychelles (454 km²; including Aldabra), the Comoros (1 862 km²), Mauritius (2 040 km²; including Rodrigues), and the French overseas departments of Réunion (2 535 km²) and Mayotte (371 km²; one of the Comoros), which is a departmental collectivity of France. Also included are the Iles Esparses, all of which belong to France: Europa (30 km²), Les Glorieuses (7 km²), Juan de Nova (5 km²), Bassas da India, and Tromelin (1 km²). These Indian Ocean islands add considerably to the overall importance of the hotspot, and bring its total land area to 600 461 km².

The natural vegetation of this hotspot is quite diverse. Madagascar is characterized by tropical rainforest on the eastern side, dry deciduous forests on the western side, and spiny desert in the far south of the country. In the far north, there is a mosaic of dry and moist forest formations, and a series of mountains are found in the north and east (Lowry et al. 1997). The Indian Ocean islands are composed of a range of relatively recent volcanic islands (the Mascarenes and the Comoros), fragments of continental material (the main group of the Seychelles), and the coral cays of the Amirantes and the atolls of the Farquhar, Cosmoledo, and Aldabra groups, as well as the five Iles Eparses. The continental and volcanic islands have high peaks that in the recent past were covered by dense forest; indeed, the Comoros (up to 5 600 mm per year on Grande Comore) and the Mascarenes (up to 6 000 mm per year on Réunion) are sometimes subjected to very high levels of rainfall. The highest peak in the Indian Ocean is the Piton des Neiges on Réunion (3 069 m), which received the heaviest downpour on record (4.9 m of rain in one week in 1980). By contrast, the Seychelles are relatively dry (up to 2 400 mm per year on Mahé).

In terms of its biodiversity, Madagascar's most striking feature is its high levels of endemism, particularly at the generic and family levels. Madagascar also has very high species diversity in certain groups of organisms, especially given its relatively small size. Both of these characteristics are best represented in Madagascar's flora: current plant diversity is estimated to be at least 12 000 species, and possibly as many as 14 000, of which around 90% are endemic (G. Schatz and P. Lowry, unpubl.). In addition, there are seven endemic plant families, which is unmatched by any other country; indeed, only Australia, New Caledonia, and South Africa are comparable in terms of plant endemism at the family level. Madagascar recently made headlines in the botanical world with the rediscovery of Takhtajania perrieri, the only Afro-Malagasy member of the primitive family Winteraceae, in the northeast of the country. It is fitting that Madagascar's signature endemic plant, the traveler's tree (Ravenala madagascariensis), is pollinated by the island's flagship vertebrate species, the lemurs.

Among vertebrates, some 283 avian species have been recorded, of which 209 breed on the island, and 109 of these are endemic (Hawkins and Goodman 2003); and, not surprisingly, no fewer than five Endemic Bird Areas have been recognized in the country (Stattersfield et al. 1998). At the higher level, 34 out of 148 resident genera are endemic, and there is also high family-level endemism, with five bird families restricted to the island. There are some extraordinary ancient relict bird species on Madagascar, such as the groundrollers, cuckoo-rollers, and mesites.

Mammals are represented by 131 species, of which 30 are bats; all but 12 species are endemic (Goodman et al. 2003; Eger and Mitchell 2003). No other country or hotspot comes close in terms of primate family-level endemism, with some five families and 15 genera endemic, and a total of 72 taxa in all (with more still to be described). This incredible primate radiation constitutes the best known of the region's charismatic species, including the aye-aye (Daubentonia madagascariensis, EN), the indri (Indri indri, EN), and Madame Berthe's mouse lemur (Microcebus berthae), at 30 g the world's smallest primate.

Although there is only one endemic amphibian family (Mantellidae) and one endemic reptile family (Opluridae), the reptiles and amphibians exhibit very high levels of endemism. Indeed, of the 340 reptile species, 314 are endemic (Raxworthy 2003), as are an amazing 215 of the 217 described amphibian species. Apart from being extremely rich in these groups, Madagascar may even be the place of origin for some; for example, it has been proposed recently that all the world's chameleons originated here. Among the flagship amphibians and reptiles are the beautiful frogs of the genera Mantella and Scaphiophryne, the tomato frog (Dyscophus antongilii), a bright red, bullfrog-sized animal found only in a tiny area in northeastern Madagascar and, of course, the chameleons.

It is noteworthy that many new species have been discovered on Madagascar in the last decade or so, and, indeed, since the publication of the last Hotspots book in 1999. For example, no fewer than 22 new mammal species and subspecies have been described from Madagascar in the last 15 years (including seven full lemur species between 1997 and 2003). Furthermore, many new species remain to be discovered and described; for example, C. Raxworthy (pers. comm.) notes that at least 100 reptile species and about 100 amphibian species await formal description.

Most of the other fauna on Madagascar is poorly known. However, some of the non-marine invertebrate groups that are reasonably well known are: terrestrial snails (651 species, all endemic); scorpions (40 species, all endemic); spiders (459 species, 390 endemics); dragonflies and damselflies (181 species, 132 endemics); lacewings (163 species, 119 endemics); tiger beetles (211 species, 209 endemics [D. Pearson, pers. comm.]); scarab beetles (148 species, all endemic); true butterflies (300 species, 211 endemics); freshwater crayfish (six species, all endemic); and freshwater shrimp of the family Atyidae (26 species, 20 endemics). Overall, total species richness for macroinvertebrate groups covered in a recent review of the natural history of Madagascar is slightly more than 5 800 species, of which 86% are endemic to the island, although several speciose groups of invertebrates are not covered in the volume (e.g., the vast majority of beetle families) (Goodman and Benstead, pers. comm.).

The smaller neighboring Indian Ocean islands are biologically closely linked to Madagascar, are under heavy pressure, and add important endemic biodiversity without adding significantly to the land area covered by this hotspot. For example, in terms of plant diversity and endemism, the flowering plants are represented by about 2 200 to 2 400 species (ca. 1 300 in the Mascarenes, 1 000 in the Comoros, and 310 in the Seychelles, several hundred of which are shared among two or more of the island groups); around 810 (34%–37%) of these are endemic (about 585 in the Mascarenes, 150 in the Comoros and 75 in the Seychelles), along with one family endemic to the Seychelles (Medusagynaceae).

Space does not permit detailed discussion of the vertebrate diversity of all the islands, although much research has been conducted on Seychelles recently, and these islands are mentioned briefly here. The Seychelles add a further 104 native breeding vertebrates, with endemics comprising one fish, 11 amphibian, 27 reptile, 14 bird, and four mammal species. In addition, the Seychelles have one endemic amphibian family —the Sooglossidae, an ancient group endemic to this area with its closest relative in the Western Ghats of India— and six endemic amphibian genera. The presence of seven species of caecilian amphibians is bizarre, as these are entirely absent from Madagascar and the other western Indian Ocean islands.

The invertebrate fauna of the Seychelles comprises 3 555 recorded species, with an estimated total of perhaps 5 100 species; of these, approximately 80% are endemic. One truly unique and amazing invertebrate flagship is the endemic giant tenebrionid beetle (Polposipus herculeanus, CR), restricted to one small island in the Seychelles, and one of the largest terrestrial invertebrates in the world. The region also supports the largest millipede (Sechelleptus seychellarum) and the only secure population of the world's largest terrestrial invertebrate, the coconut or robber crab (Birgus latro).

The hotspot includes two distinctive components of freshwater fishes. The smaller islands have depauperate faunas dominated by species that have wide marine distributions and that enter brackish and freshwater habitats to some degree. The few endemics on these islands include a cyprinodont, a chandid, and gobies. Madagascar differs in having a freshwater fauna that includes fishes of continental origin. These groups have undergone radiation on the island, resulting in 93 endemic species (of the hotspot's 97 species), and these also account for all of the hotspot's 14 endemic genera and two endemic families.

Overall, the Madagascar and the Indian Ocean Islands Hotspot (i.e., including not only Madagascar and the Seychelles, but also the remaining Indian Ocean Islands) has a total of at least 155 mammals, 144 of which are endemic; about 313 regularly occurring birds, 183 of them endemic; 381 reptiles, 367 endemic; and at least 228 amphibians, of which 226 are endemic. Plants total at least 13 000 species, and probably as many as 15 000, with a staggering 11 600 (and perhaps 13 500) endemics, and at least 310 endemic genera. The number of endemic families in this hotspot is truly exceptional, totaling 24 in all (16 for vertebrates, including fishes, and eight for plants), and far surpasses that of any other hotspot. This once again attests to the great global importance of Madagascar and its neighboring islands, and highlights its role as one of the highest priority hotspots on Earth.

The threats to Madagascar and the Indian Ocean islands are well documented, with forest destruction through slash-and-burn agriculture, mining, and logging being among the main causes of habitat loss. In Madagascar, it is estimated that around 90 000 km2 of closedcanopy primary forest and woodland remained as of 2000, with an average annual rate of loss during the 1990s of 0.9% per year (Steininger et al., unpubl.). Assuming that 90% of Madagascar was once forested (Perrier de la Bathie 1936), this equates to roughly 17% of original primary vegetation remaining. The most heavily impacted habitats are lowland rainforest, dry deciduous forests, and spiny forest. Wetlands, including lakes, rivers, and marshes, are under threat from transformation to rice fields, siltation resulting from soil erosion, and introduced species. The latter have accounted for several extinctions recently. Lemurs, some birds, and smaller mammals are very susceptible to hunting. The pet trade has also had a serious impact on endemic plants and animals of Madagascar, especially amphibians, reptiles, and succulent plants. The proliferation of exotic plant species is also recognized as a major threat affecting the biodiversity of Madagascar and the western Indian Ocean islands, and freshwater ecosystems, in particular, have been seriously impacted by alien plants such as Eichhornia crassipes (Langrand and Goodman 1995).

In the Comoros, at least 80% of the native vegetation has been destroyed since human colonization first began over 1 000 years ago. During the period 1990–1995, deforestation reached 5.8% per annum, the fourth highest rate of any country (Jolly and Fukuda-Parr 2000). Today, plantations dominate the land. Mayotte Island also was once forested, with dry, humid, and transitional types recognized. Most of this was destroyed before 1900, leaving fragments of native forest that covered only 3% of the island in 1999 (Pascal 2002), most of which (6.7 km²) is humid forest. A further 14.8 km² of the island's vegetation has been classified as secondary forest up to 300 m. Hunting is a major problem for the avifauna, and species such as the Comoro olive pigeon (Columba polleni) are becoming rare as a result.

Réunion was permanently colonized in 1646. Since then, humans have brought about the loss of 75% of the native vegetation area (around 650 km² remain) and 50% of the native vertebrate fauna (including 55% of the birds). As is often the case on recent volcanic islands, the introduction of exotic species of fauna and flora is having a huge impact on the survival of endemic species. On the Seychelles, much of the original lowland vegetation was cleared for timber production or agriculture, particularly for coconut plantations and cinnamon exploitation in the granitic islands, although significant reservoirs of biodiversity have survived thanks to the steep terrain of the high islands. The Amirantes, and Cosmoledo and Astove atolls, have also been greatly impacted by coconut plantations.

Given the importance of the hotspot, it is not surprising that there have been major efforts in biodiversity conservation, and the hotspot, in particular Madagascar, may be entering a new era in terms of biodiversity protection. In Madagascar, the government is about to embark on the third phase of the National Environmental Action Plan, with a five-year program of conservation and sustainable management actions. There are many conservation organizations involved in this effort, both international and local, and the World Bank, Global Environmental Facility (GEF), United Nations Development Program, and French, U.S., German, and Swiss bilateral aid is all being deployed specifically for biodiversity conservation.

In the Comoros, political instability has meant that conservation action has been rather piecemeal until recently, with only limited GEF and IUCN support for the establishment of a marine national park and some work on Livingstone's fruit bat (Pteropus livingstonii, CR) by local and international NGOs. The climate for collaboration is set to change, however, and further investment in establishing threatened species conservation programs, through CI and other partners, is under way; and there is a plan to establish a terrestrial national park in Mount Karthala. The Seychelles, by contrast, have several very active conservation NGOs that have had a dramatic impact on the conservation status of many of their threatened species recently. A notable example is the Seychelles magpie robin (Copsychus sechallarum, CR), rescued from the edge of extinction over the last ten years by Nature Seychelles and partners. A similar situation applies in the Mascarenes; while there are many species on the verge of extinction, considerable effort has been devoted to captive-breeding and release programs. This is particularly evident in Mauritius, where the Mauritian Wildlife Foundation, Durrell Wildlife Conservation Trust, and other partners have been prominent in rescuing species such as the pink pigeon (Columba mayeri, EN) and the echo parakeet (Psittacula eques, CR) from extinction.

As of mid-2002, the protected area network of Madagascar included 46 legally protected areas (national parks, strict nature reserves, and special reserves) covering 16 131 km² or 2.7% of the country (Randrianandianina et al. 2003). However, on September 17, 2003, at the World Parks Congress in Durban, South Africa, Madagascar's President, Marc Ravalomanana, made history when he declared his intention to triple protected area coverage over the next five years and to seek assistance from the international community for a $50-million trust fund to make this a reality. Demonstrating once again the interest of the international community, fully $24 million in commitments were made to this trust fund in the first six months following this announcement. The Global Conservation Fund (GCF) at Conservation International is assisting in the design and capitalization of the trust fund. The GCF and the Critical Ecosystem Partnership Fund (CEPF) are also actively supporting the efforts of local partners to identify priority areas for conservation, as well as to plan and create new protected areas in irreplaceable forests in the Menabe region of Western Madagascar, the extensive rainforests of Makira in northeastern Madagascar, and the Daraina region in the extreme northeast. CEPF's contribution of $4.25 million for conservation in Madagascar has played a major role in helping local partners, such as Association Fanamby, engage in biodiversity conservation at multiple levels. The partnership's support to local groups is set to further expand under a new, three-year small grants program to help Malagasy organizations undertake conservation efforts at a local scale.

A number of the Indian Ocean Islands also have at least some protected area coverage. For example, Réunion has 21 protected areas, all in IUCN category IV and totaling 231 km², while in the Seychelles, 208 km² (46% of the land area) is designated as national parks, with a further 228 km² of marine national parks. These include two World Heritage Sites: the Vallée de Mai and Aldabra. Overall, an analysis of the World Database on Protected Areas shows that there are around 100 protected areas in the hotspot, the majority in IUCN categories I to IV, covering 3% of the surface area.

Although this extremely important hotspot still faces many threats and challenges, recent developments, particularly in Madagascar, give cause for more optimism than ever before. Indeed, the major new commitments being made for Madagascar could mean that this wonderful island, once considered almost a lost cause for conservation, could quickly be transformed into a global model. This renewed interest in the region as a whole will hopefully have a significant impact in the neighboring islands as well.

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