The low roar thundering through the undergrowth grew closer. Much closer. It was first light, just after 5am, on our first hike of the day out from the (TRC), a lodge deep in the Peruvian Amazon, near the Bolivian border.
Suddenly, Yuri, my guide, stopped and pointed into the dense canopy at the source of the intimidating rumble. "Don't move," he whispered urgently. But instead of some magnificent specimen of the Amazon's apex predator, the jaguar, Yuri was waving at a small, brownish lump of fur. Gazing nonchalantly down at us, the howler monkey began scratching one of the more intimate parts of his anatomy.
Despite their diminutive size, this species is reputed to be the loudest land animal on the planet. The roar of the male, produced via a large, hollow bone in the throat, is thought to mark territory between rival groups, and can travel up to three miles.
During my three days at the TRC, I managed to see all seven of the local primate species. The large spider monkeys made spectacular leaps between branches 90ft above the ground, while the tiny squirrel monkeys were the most playful. On more than one occasion, as our paths crossed in the sweltering jungle, they descended almost to head height to check us out.
One of the Amazon's most remote lodges, the TRC lies eight hours upriver from the sleepy regional capital of Puerto Maldonado. It normally requires an overnight trip to get here, although there are lodges much closer to town, including two run by the Centre's owners, Rainforest Expeditions, where visitors stop over en route.
"Our 'why' is conservation. That is what drives the business. Tourism is a way to achieve that end," Kurt Holle, Rainforest Expeditions' general manager told me as he explained how the company was created in 1989 with the initial purpose of preventing loggers accessing what is now the Tambopata Nature Reserve.
Since then, the company has co-founded the Tambopata Macaw Project, dedicated to studying the region's spectacular birdlife in partnership with Texas A&M University. The lodge normally hosts four or five researchers at a time, mainly from the project but also including primatologists, conservation ecologists and other scientists from around the world. Their board and lodging is heavily subsidised by the tourism operation — visitors to the lodge have the chance to mingle with the experts and pepper them with questions.
Here, with the Andean foothills jutting out of the clouds on the horizon, macaws, parrots and parakeets gather most mornings for an earthy breakfast amid a cacophony of guttural squawking and a rainbow palate of flashing blue, green, red, and yellow wings.
But the Peruvian Amazon, three times the size of the UK and home to numerous biodiversity records, is not just a twitchers' paradise. Along with its estimated 806 bird species, it also has a staggering 293 types of mammal, 2,500 butterfly species and more than 7,000 kinds of flowering plants.
Many species are hard to glimpse; visitors make their luck by spending long hours tramping through the sweltering rainforest. With humidity extremely high and long trousers recommended to minimise mosquito bites, the TRC is for those seriously motivated to see wildlife. Returning to the Centre was always a treat.
Despite its size, the Peruvian Amazon is under pressure. Oil drilling, logging, gold mining and poaching are taking their toll. A new road connecting Brasilian raw materials with Peru's Pacific ports passes just 30 miles from the Tambopata Nature Reserve. With it come development opportunities for isolated rainforest communities but also the potential for widespread deforestation.
Few things are as satisfying as knowing that your tourism dollars are helping to save this fragile wilderness, especially as you sip an icy beer on the TRC patio while wild parrots scatter against the sunset. (Simeon Tegel/The Independent)