The unique lemurs of the island Madagascar

Madagascar will always have a warm place in my heart, this is the place where it all started. All the amazing animal and plant species, which you cannot find anywhere else in the world. This is about 89% for plant species, 95% of reptiles and 92% of mammals! The most popular endemic species are the group of the lemurs (Lemuroidea).

Madagascar is an island in the ocean ocean, it is located approximately 400 kilometres of the coast of East Africa. with over 500.000 km2 it is the fourth largest island in the world. Madagascar has not always been an island. It started as part of the supercontinent Gondwana. When Gondwana broke apart Madagascar remained connected to the Indian subcontinent. It remained connected till about 88 million years ago. After that, it was an isolated island.

The island Madagascar

Due to this isolated location, the native plants and animals were able to evolve in species that we cannot find anywhere in the world. Although this does not entirely count for the lemurs, they arrived on the island after it became isolated. Lemurs are believed to be evolved from mainland African primates. Which means that their ancestral much have crossed the Mozambique channel. which is a deep channel between Africa and Madagascar, they crossed the open ocean!

The most widely accepted theory of how the ancestors of lemurs have reached Africa is by rafting. where very small populations rafted from nearby Africa. Most likely on tangled mats of vegetation, across the Mozambique channel. It is unknown how many of these rafting events took place. But all 108 species of lemurs originate from the common ancestors that arrived on Madagascar this way.

The unique lemurs

The 108 species of lemurs that exist today can be categorized into 5 families; Daubentoniidae, which consists of the aye-aye. Lepilmuridae, consisting of the sportive lemurs. Indriidae, which includes the indri, sifakas and woolly lemurs. Cheirogaladeidae, which are the mouse, dwarf and fork marked lemurs. The last family is Lemuridae which consists of the rest of the lemurs.

The Daubentoniidae only has one species in its family; the aya-aya which looks a bit unusual for a lemur. It has long fingers, with a special thin middle finger and rodent-like teeth. It is a nocturnal animal, meaning he is active at night. There used to be a second member of the family, but this species became extinct somewhere in the last 1000 years. The other families have between 19 and 41 species. Summing up to a stunning variety of 108 different lemurs.

How do lemurs coexist in such large numbers

Due to the absence of other mammals, lemurs have managed to adapt to many different niches within many different habitats. These niches would normally have been occupied by, for example, monkeys, squirrels, woodpeckers, and/or ungulates. Due to this diversity of adaptations for specific ecological niches, the habitat selection among lemur families and/or genera are often very specific.

This specification is to avoid competition between the different species. The type of food is the most common form of specification. But also a subtle difference in substrate preferences, forest strata used, activity cycle, and social organization, enable lemur species to coexist.

All lemurs, and particularly the smaller species, are affected by predation.  Although not all predators are what you would expect in nature. The mist significant predator for day time active lemurs are humans, including their domestic cats and dogs. Even though there are taboos in Madagascar that forbid the eating of certain lemurs. Other natural predators include; the fossa,  snakes, diurnal birds of prey, and crocodiles. 

Other endemic species

Not only the lemurs are special about Madagascar. Its distinctive ecology has led some ecologists to refer to Madagascar as the “eighth continent”. And the island has been classified by Conservation International as a biodiversity hotspot. As mentioned before, about 90 % of Madagascar’s almost 15.000 plant species cannot be found anywhere else in the world. Which includes five whole plant families! And the island is home to two-thirds of the world’s chameleon species, including the smallest known. Some people believe that Madagascar is the place where chameleons first evolved.

Human influence

Humans only arrived in Madascar about 1500-2000 years ago. With people coming from India, south-east Asia and Africa, each of them having lasting contributions to the malagasy culture. But in the short time human settlement, it quicly became one of the most threatened ecosystems of the planet. It suffers great environmental degredation almost all over the country. The major envrionmental problems include: deforestation and habitat destruction, agricultural fires, erosion and soil degredation, overexploitation and introduction of alien species.

Deforestation

The most widely used method to convert natural vegetation into rice fields is ‘slash and burn’. Also called ‘Tavy’ in Malagasy. Typically, it spans over an area of 0.5 to 1 hectare of forest. The forest is cut and burned to prepare for agricultural purpose. The initial reproduction cycle is 2 years. The land needs to be fallow for about 4 to 6 years before another reproduction cycle is possible. The soil is only about to complete 2 or 3 cycles of reproduction. After those cycles, the nutrients in the soil are exhausted.

Due to the complex ecology of a rainforest, the area will not recover back to its original state. Shrub vegetation and/or alien grasses will take over the land.

Logging for timber is especially a problem in the rainforests of eastern Madagascar, where the tropical rainforests are growing. The high value for Malagasy hardwoods makes illegal logging a significant problem. This even occurs within protected areas. Timber extraction generally doesn’t drive deforestation directly. Instead, it degrades forests and increases the likelihood of future clearing for subsistence agriculture or other use. 

Agricultural fires

Fires that the made to clear the land for agricultural purposes spread into the primary forest. Causing damage that the forest is often not able to recover from, or not fast enough before the next fire comes.

Erosion

Due to the erosion of the famous red soil of Madagascar, the rivers turn blood red before they end up polluting the Indian ocean. Astronauts have remarked that it looks as if Madagascar is bleeding to death. The scale on which this happens makes it one of Madagascar’s greatest environmental problem. Soil erosion happens due to the deforestation of the land.

When you have a healthy forest the vegetation holds the soil with its roots network. The soil cannot be held in place without this network of roots. Resulting in the erosion of the soil. In some areas it as much as 400 tons/ha of soil per year. 

Overexploitation

Many native species of Madagascar are hunted. The inhabitants for Madagascar hunt these species to be able to provide for their families. It has been illegal to kill or keep lemurs as a pet since 1964, but lemurs are still hunted on a big scale. Not only lemurs are a victim of hunting, but also tenrecs and carnivores species are being hunted for their protein.

Species such reptiles and amphibians are captured out of their natural habitat. which is done for the international pet trade. This mostly affects; chameleons, geckos, snakes and tortoises.

The waters around Madagascar are rich in fish and provide an important source of income for villagers. Unfortunately, the fishing in these waters is poorly regulated. Foreign fishing boats are fishing on a great scale, leaving very little fish behind. Not only creating an unsustainable way of fishing but also leaving nothing behind for the local people. Unsustainable harvesting is not limited to fish. Sharks, sea cucumbers, and lobster are also victim or large scale harvesting.

Alien species

The introduction of alien species has doomed many of Madagascar’s endemic species. The best example of the damage done by introduced species can be found in the rivers and lakes. Adaptable and aggressive tilapia, introduced as a food fish, have displaced the native cichlids. 

How this affects the lemurs

All these environmental problems affect the lemurs on many scales. Not only are they being hunted, but their habitat has also declined significantly. And it is still declining. This is visible in their conservation status. Today 98% of the lemurs’ species are threatened with extinction. And 31% of all lemur species are now critically endangered. They are just one step away from extinction.

For at least 17 lemurs species help already came too late. They did not manage to survive the significant human influences on the island. They most likely went extinct because there was simply not enough habitat left for them, as these species were all larger than the species that are currently living in Madagascar.

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