VOHIBOLA, Madagascar: Under a leaden sky, six rangers walk silently in single file through Vohibola, one of the last primary forests in eastern Madagascar.
Alert to the slightest movement and sound, Michael Tovolahy's patrol is tracking poachers who are inflicting grievous harm to this jewel of biodiversity.
The poachers are targeting lemurs, primates battling the threat of extinction, and are chopping down trees, some of them rare hardwoods, to burn for charcoal.
"In this forest, there are at least 20 indigenous animal species, including six types of lemur, and 150 species of tree," says Tovolahy, whose nickname is Nabe.
"Because of these logger-poachers, I fear that this forest will one day be no more - it will be just an empty space, where developers will grow walls of concrete."
A terrible irony is that a 2014 documentary, Island Of Lemurs, which did so much to draw attention to the cuddly animals' plight, unwittingly encouraged a market to have them as caged pets.
Some kill the harmless creatures for food, others sell them as pets - and to get to their prey, they chop down precious tropical trees.
"Nocturnal lemurs are very easy to capture because they sleep in the daytime," explains Tovolahy.
The poachers cut down the trees surrounding their nest, which provides the lemurs with a means of flight. All they have to do then is to shake the tree until the animal falls out.
Lemurs are among the many wildlife treasures that are unique to Madagascar.
Out of 111 recorded lemur species, 105 face the threat of extinction, says the Lemur Conservation Network (LCN).
Other damage to Vohibola and its natural population is being inflicted by the simple need for wood for cooking.
The forest patrol frequently encounters the dismayng sight of empty spaces and mounds of bark - the traces of illegal logging to take trees, burn them and sell the charcoal to Madagascans.
"They take rare woods such as ebony and use it to make charcoal - it's so sad," says Tovolahy.
Eric Rabenasolo, director-general for forests at the environment ministry, says that Madagascar's nine million hectares (22.25 million acres) of forests are shrinking each year by between 50,000 and 100,000 ha.
Vohibola itself is a haven for an extraordinary species - the mouse lemur.
From its head to the tip of its tail, this nocturnal animal (genus Microcebus) measures under 27cm, making it the world's smallest primate - and, according to the International Conservation of Nature (IUCN), among the most endangered of all vertebrates.
The state is trying to boost awareness of the dangers of such trafficking, urging people for instance to check the source of their cooking charcoal and encouraging villages to report illegal logging to the authorities.
The message often goes unheard in a country where three-quarters of the population live in poverty.
Poachers have a well-founded reputation for violence and their connections with locals mean that police can rarely make arrests.
"It's the villagers themselves who tip off the poachers that the police are coming," says Cecilien Ranaivo, mayor of the Ambinaninony district, which includes Andranokoditra.
"So obviously they don't succeed in making many arrests."
During Tovaly's patrol, the team comes across a poachers' hideout - an encampment the size of a small village, with about 20 makeshift huts that have clearly been abandoned in a hurry.
Tovolahy expresses his frustration. His resources are limited: the patrol comprises volunteers armed with sticks or bows and arrows and can only seek to scare off poachers, rather than tackle them head-on.
"We will never be able to fight the poacher-loggers by ourselves," he says. "What's needed is armed men, empowered by law to use force if necessary."
Exasperated by the authorities' powerlessness, environmentalist Stephane Decampe has decided to launch his own mission to protect the lemurs.
Decampe, a French-Madagascan dual national, co-owns the Jungle Nofy Hotel, a lodge which accommodates tourists who go down the Pangalanes Canal, an interconnected series of rivers, man-made lakes and waterways that runs down Madagascar's east coast..
He patrols the canal three nights a week in his boat to track to the poachers.
"They come from the town of Tamatave (70km north of Ambinaninony), along with their wives and children," Decampe said.
"They are dropped off here by boat, and have food but no meat ... so they eat lemurs," he said.
He and his wife Angelique also recover lemurs that families use as pets.
"We set them free," she said. "But when we last went on holiday, the poachers poisoned them in an act of revenge."
The battle to save the lemurs has caused tense relationships with the authorities - local officials, say activists, are getting kickbacks from some of the traffickers.
That insinuation causes Mayor Ranaivo to sputter angrily, accusing the campaigners of having "political motivations."
A dozen environmentalists were arrested in early April.
"They accused us of illegally cutting down trees and destroying loggers' businesses," sighed Tovolahy. "And while all this was going on, the real poachers were hauling out their booty.