ALTO MADRE DE DIOS RIVER Peru (Reuters) - Six Mashco Piro tribeswomen crouched low as they escaped back into the jungle after raiding a remote lodge in Peru's Manu National Park in the western Amazon, clutching newly prized tools: metallic cooking pots.
The brazen daytime foray into the tourist retreat in May was a rare appearance by one of the world’s most reclusive tribes that is increasingly chancing contact with the outside world.
The Mashco Piro have clashed in the past with loggers, poachers and drug traffickers who invaded their jungle enclaves, but anthropologists say the lure of modern tools is now tempting them closer than ever to far-flung villages and tourist camps.
"It's a technological revolution," said anthropologist Klaus Rummenhoeller, who has been studying Amazonian tribes in Peru since the 1980s. "Imagine you live in the wild and only have stone axes, and then you're given machetes."
Their sorties are dangerous, exposing them to the threat of violent encounters with terrified locals and modern-day diseases against which the hunter-gatherers have little immunity.
The Mashco Piro have historically rejected outsiders, surviving enslavement during Peru's bloody rubber boom in the late 1800s and rebuffing the advances of Christian missionaries throughout the last century.
But in the past three years there has been a spike in sightings near the Manu National Park as the Mashco Piro, clad only in loin cloths and armed with bows and arrows, emerge during the dry season in clearings along the Alto Madre de Dios River.
"They sounded like birds," said Guillermina Loaiza, a cook at the lodge who disturbed the tribeswomen as they rifled through her kitchen during the recent raid. "I thought it was another tourism agency playing a practical joke."
The tribe is estimated to number no more than 600 and is split into several groups who constantly move through the jungle, occasionally constructing makeshift shelters on river banks where they dig for turtle eggs.
Peru's government prohibits physical contact with the Mashco Piro and another dozen so-called "uncontacted" indigenous tribes, primarily for their wellbeing. Their immune systems carry little resistance to illnesses that other humans carry.
"It's extremely urgent because there are more of them every time, and it's a relatively highly transited area," said government anthropologist Luis Felipe Torres. "Anything could happen."
Torres said a Catholic priest and mayor of one local town in Peru's eastern reaches near the border with Brazil were among a small group who had tried to tempt the Mashco Piro out of their hideouts with rewards, pitying their primitive existence.
Authorities say they can do little to prevent individuals ignoring the contact ban because there is no penalty attached.
Instead, armed with a budget of just $600,000 a year, a government team tasked with preventing the Mashco Piro and other uncontacted tribes succumbing to modern diseases strives to dissuade outsiders from making contact.
It has happened before. In the 1980s, human-carried germs wiped out half of Peru's Yora tribe after illegal loggers penetrated deep in the forest along roads built to facilitate oil and gas exploration.
Three years ago, doctor Fernando Mendieta helped prevent an outbreak of respiratory infections wreaking havoc among a group of semi-isolated of Machiguenga Indians after a Canadian searching for a lost Inca city passed through their village.
But Mendieta said he would be wary of treating the Mashco Piro because of their aggressive reputation. They killed one local man and wounded a park ranger with arrows in 2011.
"I'm not going to be the first one to try and inject a Mashco Piro with a shot," Mendieta said.
The government task force is erecting signs warning against approaching the Mashco Piro, but it may be too late to halt a rising trend.
"They should have put up the signs before, when they (Mashco Piro) first started showing up," said Romeria Rivera, a leader in the village of Shipetiari where the wooden huts are raised on stilts to avoid flooding.
Wanting to placate the Mashco Piro, locals in the nearby town of Diamante at times leave machetes and bananas out on the shore of Alto Madre de Dios River, said logger Henry Bonifacio.
"Once, we left them a cold soda," Bonifacio said. "One man grabbed it, felt the cold and then dropped it and left."
Editing by Richard Lough and Kieran Murray