It starts at 2am, an unearthly chorus of high-pitched wails fills the forest. It's as if the indri, the largest living lemurs, are singing at the door of my simple rainforest lodge in the lowland jungle of eastern Madagascar. In reality, they could be as far as 4km away.

Unique to Madagascar, lemurs are some of the oldest primates in the world, and their survival is thanks mainly to the isolation of this 'lost continent' which drifted away from the African mainland 160 million years ago. The last inhabited place in the world, Madagascar's been home to man for just 2,000 years.

Naturalists such as Sir David Attenborough have filmed wildlife series here, and DreamWorks animation studio even based a successful film franchise on the island's cute and cuddly inhabitants.

But cartoon capers aside, this former French colony has been dogged by political instability since a coup in 2009. With democratic presidential elections planned this year, however, Madagascar appears to be starting a new chapter and Lonely Planet has tipped it as one of the top 10 countries to visit in 2013.

The island is vast - bigger than the UK - and poor infrastructure can make journeys long and expensive. To save time and money I join a small group tour with adventure specialists Explore, travelling from the north-east to the south-west.

It's drizzling with warm rain as we set off on a muddy trail through Andasibe-Mantadia National Park, one of the best places to see indri in the wild. Native trees, stretching almost 30m into the sky, are draped with spiralling vines, like Rapunzel's tangled locks tumbling from a tower. Curved buttress roots extend their grip across a forest floor wriggling with life - including maggot-like leeches that stick to my skin like superglue.

Lemur spotters, locals from the nearby village, race ahead through the dense undergrowth, hoping to find some of the nine lemur species that live here.

I'm amazed at just how close we can get to the animals; a common brown lemur comfortably forages for berries only meters from our feet, while above us a family of indri propel themselves through the trees with an admirable combination of athletic strength and balletic grace. Only the painfully shy but irrisistably cute grey bamboo lemurs are easily frightened.

A meagre 11% of the original forest remains in Madagascar, mainly in the eastern region. In 2007, the Ranomafana National Park - which lies further south, but at a higher elevation - was classed a world heritage site.

At sunrise, the ghosts of palm-fringed hills disappear into a purple and yellow-hued horizon. A female belted chameleon clings tightly to a branch by the roadside; by daylight she'll return to the forest canopy.

Only a few decades ago, this whole area was covered in forest. Much has been destroyed by slash and burn agriculture and, as a result, many species of lemur are now extinct.

Ranomafana is home to the last two true breed greater bamboo lemurs, a father and daughter whose family were killed by natural predator, the fosa. As they playfully grapple each other in the treetops, it's sad to imagine their sub-species will inevitably die out.

The transitional government enforces strict controls in Madagascar's national parks, dishing out 20-year prison sentences to anyone who kills a lemur or cuts down a native tree. But coercion isn't the only tool for change; by employing locals in the parks and giving 50% of entrance fees back to the community, Malagasy people have good reason to take care of their environment.

Theo, whose family belong to the Tanala tribe, grew up in the forest, wearing only a loin cloth and sleeping in temporary huts. His family were relocated to a nearby village when the area was declared a national park in 1986.

He used to kill birds and lemurs, but now uses his skills to track them for tourists, and even assisted David Attenborough's BBC crew when they filmed here.

"These days I'm a bird nerd," he says, smiling. "I say the lemurs are my boss, because without them people would stop coming and I wouldn't have a job."

There are 22 million people living in Madagascar, and as the numbers continue to grow, so too does the pressure on natural resources; presently, an alarming 85% live below subsistance level.

Capital city Antananarivo - town of the thousands - lives up to its name, with passenger-crammed mini buses and zebu-drawn carts locked in permanent traffic jams. Roadside stalls sell stacks of yellow foam mattresses and glimmering car exhausts, hanging from a bamboo T-frame like wind chimes.

Leaving the city, we drive through a patchwork of green fields and irrigated rice paddies that dance with reflections of the clouds. Rice is a religion for the Malagasy and forms the basis for every meal - delicacies include rice cakes (slightly sweet patties fried in sugar) and far less palatable Rananapango (a tea made by pouring boiling water into a burnt rice pan).

Crossing the central highlands, we pass mud brick houses charred black by smoke from open charcoal fires. Ours is the only van on the often pot-holed roads, passing local Merina people in typically garish, colourful clothing, walking to the local market, a social highlight of the week.

As we move further into the arid south, faces get darker, hair becomes curlier and the soil turns terracotta red. There are 18 distinct tribes in Madagascar, whose everyday lives are regulated by fady (taboos) and respect for the ancestors.

Home to the Bara people, a polygamous tribe of African descent, the Isalo National Park is formed of Jurassic sandstone formations where families of ring-tailed lemurs have been known to sunbathe on the rocks.

Spiny-tailed lizards scamper over the bulbous roots of thousand-year-old elephant's foot plants, seeking shelter from an oncoming storm. This area is prone to furious bolts of lightning and many of the trees have evolved to be fireproof.

The rocks are filled with small holes, used by the Bara people as temporary burial chambers. Once a body has decomposed, bones are removed and smeared with honey in a 'turning of the bones' ceremony, then laid finally to rest at a higher elevation.

Life here is hard but the poorest region is Toliary, on the south-west coast, straddling the Tropic of Capricorn. Yet it's in Anakao, a fishing village wrapped by the warm Indian Ocean, that I encounter more smiles and laughter than anywhere else on my trip.

We arrive by boat from the region's main city Tulear - by zebu cart, the journey is 10 hours across sand dunes.

The local village spills onto the exotic shell-strewn beach, with locals working, playing and even washing dishes in the sand. The Vezo people, muscular and athletic, are fishermen whose lives revolve around the sea: young boys learn to sail traditional pirogues (flat-bottomed boats with sails made from bedsheets or stitched-together rice sacks) by playing with toy replicas; and when they die, fishermen's bodies are wrapped in their fishing nets and sails.

Their lives feel far removed from political movements in the capital, but the call for change is growing stronger.

"I think the Malagasy people are ready for something different," says our guide Claude, referring to the upcoming elections.

Like the piercing cry of the indri, its a call that's travelling far and wide.

Travel facts:

:: Sarah Marshall travelled as a guest of Explore on their 15-day The Lost Continent tour of Madagascar. Departures from March to November 2013 cost from £2,247 per person including flights, accommodation, guides and most meals. Visit or call 0844 499 0901.