Indian Ocean islands

Seychelles

The 115 islands which make up the Seychelles can be divided into two types, granitic islands or coralline islands, with the biodiversity differing between the two types.

The older granitic islands, once part of the supercontinent Gondwanaland, are home to a much higher number of endemic species. The younger coralline islands are also important, supporting seabird colonies, turtle rookeries and most of the archipelago’s coral reef systems.

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Indian Ocean islands fact file

Indian Ocean islands – overview

The Indian Ocean is the smallest of the world’s three major oceans and spans over 6,200 miles (10,000 kilometres) from the southern tip of Africa to the western coast of Australia. In the southwest it joins the Atlantic Ocean and to the east it joins the Pacific Ocean. The islands of the Indian Ocean are formed either from continental fragments, such as Sri Lanka and Madagascar, or have volcanic origins, such as Mauritius and the Comoro Islands. The diversity of species on the Indian Ocean islands is varied but one thing many of the islands have in common is high levels of endemic species – they contain many species that have evolved in isolation from the mainland and occur nowhere else on Earth.

Barrow Island

Located off the north-west coast of Australia, Barrow Island was formed around 8,000 to 10,000 years after being separated from mainland Australia by rising sea levels.
The main habitat on Barrow Island is spinifex grasslands. However, there are also sandy beaches, rocky shores, dunes, salt flats and reefs.
Barrow Island is home to nearly 2,800 species, with at least 24 of those being endemic species and subspecies.
The main threat to the biodiversity of Barrow Island is the development of gas and oil industries on the island, which understandably raises environmental concerns.
Standards and procedures have been put into place to try to safeguard the island’s wildlife, such as site speed limits and driver awareness training, and trapping and relocation of animals before clearing any sites on the island.

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Explore our page on Barrow Island and discover the wealth of species found there.

Christmas Island

Christmas Island, a territory of Australia, is the summit of a submarine mountain and boasts a wide range of habitats including coral reefs, cliffs, rainforest and mangrove forests.
The location of the island near to the equator has resulted in a diverse range of wildlife being found there.
Christmas Island has a huge diversity and abundance of land crabs, including about 120 million Christmas Island red crabs, and is the only known nesting habitat of the Endangered Abbott’s booby left in the world.
In the past, 25 percent of the native forest was cleared due to phosphate mining, and introduced populations of feral cats, rats and mice have also impacted the wildlife found on the island.
Mining is now restricted to previously cleared areas and in 1980 Christmas Island National Park was opened which protects 63 percent of the island.

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Cocos (Keeling) Islands

The Cocos (Keeling) Islands are an Australian territory located in the east of the Indian Ocean.
The territory consists of two coral atolls and twenty-seven coral islands. The northern atoll is just one island, North Keeling Island, whereas the southern atoll is composed of the South Keeling Islands.
North Keeling Island and the surrounding marine area extending 1.5 kilometres from shore form Pulu Keeling National Park. This park, which is an example of an atoll in its natural state, is the only seabird breeding area within a radius of 900 kilometres and supports eight species of seabird of special conservation significance.
North Keeling Island supports the Cocos buff banded rail, the only endemic bird to the Cocos (Keeling) Islands, as well as numerous land crabs, some of the National Park’s more abundant inhabitants.
Nearly all the natural forests in the Southern Keeling Islands have been cleared and replaced with coconut plantations or other introduced species. This, combined with predation by feral cats and rats and competition for food with feral chickens, is thought to be the reason why the Cocos buff banded rail is now extinct on the southern atoll.
The marine environment of the Cocos (Keeling) Islands has not been greatly affected by human activity.

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Comoro Islands

The Comoro Archipelago, located in the northern end of the Mozambique Channel, was formed by volcanic activity almost eight million years ago.
The four islands which make up the archipelago, Mayotte, Grande Comore, Moheli and Anjouan, each differ in age, which is reflected in their geography. Grande Comore, the youngest of the islands, is dominated by the active volcano Mount Karthala.
The Comoros provide a wide range of marine and terrestrial habitats, including mountainous areas, grassy/shrubby savannahs, evergreen forests, mangroves and coral reefs.
Having only formed recently in geological terms, the Comoro Islands do not support a wide variety of species, as there has not been much time for species to colonise the islands. For example, there are no land mammals or amphibians.
The islands do have a lot of endemic species, including the Endangered Livingstone’s flying fox, which is one of the world’s largest bats, and four scops owl species, one endemic to each island.
Deforestation is a major threat to the biodiversity of the Comoro Islands and to the livelihoods of the local people, as when the trees are cut down the topsoil which holds onto water is swept away by tropical rains, decreasing the soil fertility. Over the past 20 years, the islands have had one of the fastest rates of deforestation in the world.
Conservation efforts are underway, such as a project on Anjouan to help rural populations improve the sustainability of their land management and use of natural resources, and the creation of a marine park in Mohéli.

Find out more about conservation in the Comoro Islands »

Java and Sumatra

The Indonesian islands of Java and Sumatra lie to the east of the Indian Ocean. They were formed by volcanic activity, and each has a range of mountains along the length of the island.
Java is the thirteenth largest island in the world but holds the largest human population of any island, with over 130 million people.
The western Java mountain forests boast a rich variety of flora and fauna, with many endemic mammal species, and still hold many species which are now extinct from other areas of Java. However, only five percent of the original habitat remains in this area, with soil erosion and fires threatening the remaining fragments.
Ujung Kulon National Park, in the south-western tip of Java, contains the largest remaining area of lowland forest in the Java plain and is the last viable natural refuge for the Javan rhinoceros.
Sumatra is home to a very rich variety of plants and animals - there are more than 15,000 known species of plants and it is the only place on Earth where you can find tigers, elephants, orangutans and rhinos in one area.
Sumatra has one of the world’s highest deforestation rates. Between 1985 and 2007 Sumatra lost 48 percent of its forest. The forest is being cleared to make room for pulpwood and oil palm plantations, and as a result of commercial and illegal logging.
Many conservation organisations are working with local partners in Sumatra to protect the remaining natural habitat. In 2004 the Indonesian government established the Tesso Nilo National Park after more than four years’ work by many local groups led by WWF and supported by the Critical Ecosystem Partnership Fund.
WWF’s Forest Conversion Initiative is working with producers, investors and retailers around the world to ensure that palm oil and soy plantations are not being expanded into forests of outstanding and critical importance.

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Madagascar

Madagascar split from mainland Africa about 165 million years ago and from the Indian subcontinent 80 to 100 million years ago. Due to this long period of isolation, large numbers of endemic species have evolved on Madagascar.
Approximately 80 percent of the 14,000 vascular plants and 96 percent of the snakes and chameleons are endemic.
Madagascar’s most famous endemic inhabitants are the lemurs, a group of primates that are found nowhere else in the world.
The baobab tree also demonstrates the high endemism and diversity of Madagascar’s wildlife, with six of the eight species found in the world only growing on Madagascar.
The main threats to the biodiversity of Madagascar are widespread clearance of habitats, mainly for firewood and charcoal production, as well as invasive species and the overexploitation of natural resources.
It has been estimated that only 17 percent of the original vegetation remains, with the centre of Madagascar having been almost entirely deforested.
In recent years there has been an increase in protected areas and the development and implementation of conservation strategies for many of the endangered and endemic species. The major challenge for Madagascar is integrating environmental policy with human wellbeing.

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Maldives

The greatest diversity of life in the Maldives is found in the colourful coral reefs, where over 1,100 species of fish have been found. Life on the coral reefs shows high diversity but low abundance.
Though terrestrial biodiversity is more limited, and there are few endemic species, there are still about 580 plant species and over 170 bird species which have been recorded in the Maldives.
The main threats to the biological diversity of the Maldives are habitat destruction, overexploitation of natural resources and climate change.
There have been some measures taken in the Maldives to conserve biodiversity. Several marine and bird species have been protected, and at 25 marine sites only diving and bait fishing are now allowed.
In 2013 the Republic of Maldives pledged to become the first nation where the entire country and its Exclusive Economic Zone will be a UNESCO Biosphere Reserve. These are sites established by countries to promote sustainable development based on local community efforts and science.

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Mascarene Islands

The Mascarene Islands are made up of three main islands, Réunion, Mauritius, and Rodrigues, and a number of smaller islets.
The Mascarene Islands were formed by volcanic activity.
The vegetation of Reunion and Mauritius was once quite diverse and included coastal wetlands, dry forest, rainforest and palm savannah. However, the majority of this original cover has now been lost.
Introduced animals have caused a range of problems, with grazers and herbivores devastating the habitat, and rats, cats and mongooses preying on endemic animals.
The number of endemic species on Mauritius is high due to the island’s age, location and period of isolation, and the island was designated as a Centre of Plant Diversity by the IUCN and WWF due to the large range of plants.
Unfortunately, although the Mascarenes still have many endemic species they are better known for the number of species that have gone extinct - most famously the dodo from Mauritius.
Conservation efforts are underway. In Mauritius there are three Ramsar sites of international importance, as well as two marine parks and eight islet national parks, while Rodrigues has four marine reserves and one multiple use marine protected area.
In Mauritius, actions taken include banning coral sand extraction, managing invasive species and monitoring and rehabilitating coral reefs. There have been positive results, with former sand mining sites showing recuperation, increases in fish abundance, and species such as the Mauritius kestrel now increasing in numbers.

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Seychelles

The 115 islands which make up the Seychelles can be divided into two types, granitic islands or coralline islands. The biodiversity differs depending on island type, with the granitic islands showing higher levels of endemic species.
Four of the coral limestone islands are part of the Aldabra atoll, the largest raised atoll in the world, which was designated a world UNESCO site in 1982. The Aldabra atoll provides a home for over 400 endemic species and subspecies, including a population of over 100,000 Aldabra giant tortoises, the world’s largest giant tortoise population.
The Seychelles has been recognised as a biodiversity hotspot by Conservation International and has high levels of endemic species as the islands have been isolated for billions of years. Endemic species include the coco-de-mer, an Endangered plant which produces the largest seeds of any plant in the world, as well as the Critically Endangered jellyfish tree and the Endangered Seychelles white-eye, which was brought back from the brink of extinction due to focused conservation action.
Invasive species are the main threat to the forest areas of the Seychelles whereas climate change is considered to be the primary threat to the coral reef systems, which were severely impacted by a coral bleaching event in 1998. Subsequent bleaching events have provided evidence which suggests that it is likely to be changes in climate which most threaten the corals.
The Seychelles became the first country in the world to protect 50 percent of its land, fulfilling its obligations under the Convention on Biological Diversity to ensure conservation of the islands’ biodiversity.

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Socotra

Composed of four islands and two rocky islets, the Socotra Archipelago, which belongs to the Republic of Yemen, is located in the northwest of the Indian Ocean.
The geology and climate of the islands varies. Rain-drenched mountains are able to support evergreen bushes while other areas are desert-like and only drought-adapted plants are able to grow.
Nicknamed the ‘Galapagos of the Indian Ocean’, Socotra has incredibly high levels of biodiversity and many endemic species, and was recognised as a World Heritage Site by UNESCO in 2008.
The fauna is very rich and 37 percent of the plant species are endemic, including the well-known dragon’s blood tree.
The Socotra archipelago is important for animals, with BirdLife International identifying 22 Important Bird Areas.
With 75 percent of the land area included in national parks, sanctuaries or areas of special botanical interest, the majority of areas important for threatened species are protected.
The main threat to the biodiversity of Socotra is the development of infrastructure, including a new airport and new roads. However, this does open up the potential for managed ecotourism.

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Sri Lanka

Sri Lanka is a continental island located at the southern point of the Indian subcontinent, separated from south India by the Palk Strait.
Identified as one of 18 biodiversity hotspots in the world, Sri Lanka has the highest biodiversity of flowering plants and all vertebrates except birds in Asia.
The climate of Sri Lanka can be grouped into three main areas: dry zone, intermediate zone and wet zone. Nearly all of the country’s woody endemic plants and 75 percent of the endemic animals are located in the wet zone rainforests.
The main threat to Sri Lanka’s biodiversity is the demand for land for human use. Much of the rainforest has been cleared for coffee, tea and rubber leaving only 1.5 percent of original forest cover remaining, which is itself highly fragmented.
Invasive species are increasingly becoming a problem, with aquatic ecosystems being particularly threatened.
In 1994 Sri Lanka signed the Convention on Biological Diversity which led to the development of an action plan which identified the main issues and recommended actions to be taken.
Most of the remaining habitats in Sri Lanka are now protected, with about 30 percent of the nation’s land area getting some natural resource management.

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Indian Ocean islands news

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Find out more about the Indian Ocean islands:

Barrow Island

Department of Environment and Conservation (Western Australia): Barrow Island Nature Reserve and the Gorgon Project

Christmas Island

Australian Government: Christmas Island National Park

Cocos (Keeling) Islands

Comoro Islands

Java and Sumatra

Madagascar

Maldives

Mascarene Islands

Seychelles

Socotra

Sri Lanka

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