Gliding down the tambopata River in the Peruvian Amazon, I understand the luxury of being on a boat at night in the jungle. The air is thick with 35°C heat and 99 per cent humidity. The constant breeze generated by our moving vessel offers much-needed respite from the sweltering conditions, while also keeping the relentless mosquitoes at bay.
Chris Ketola, head field research coordinator for conservation NGO Fauna Forever, is standing at the bow. Using a powerful torch, he is searching for caimans lurking in the dark waters. Caimans are mostly nocturnal, which is why we are out at night. Three species inhabit this region: the white, black and dwarf caiman (Caiman crocodilus, Melanosuchus niger and Paleosuchus trigonatus).
I am part of a crew of five and we are here to record any caiman we see and, where possible, catch them to gather crucial data such as body measurements. This will help us to learn more about caiman biology and assess population health, which will aid in the species’ conservation.
After 20 minutes, a large shape drifting in the river’s strong current comes into view. We quickly realise it’s a huge tree, likely uprooted in a storm the previous night, and we are on a collision course with it. Instincts kick in and both Pipi, the boat driver, and Chris spring into action. Pipi, sitting at the back of the boat and unable to see ahead, depends entirely on Chris for prompts and accurate directions.
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Meanwhile, Chris uses his torch to deliver a series of complex light signals that help Pipi with navigation. With calm precision, Pipi narrowly dodges the log. I let out a sigh of relief but everyone acts as if the near miss was simply part of the night’s routine. Moments later, the reflective eyes of a caiman catch in Chris’s torchlight – two glowing orange lights close together, just above the water’s surface. We alter our course, approaching slowly and quietly.
I first fell in love with the Amazon after a trip to Tambopata in 2017 and dreamed of immersing myself in this environment for an extended period to document its beauty. As the most biodiverse terrestrial environment in the world, with trees as far as the eye can see, the Amazon offers the perpetual thrill of discovery – you can find things here that few or no others have seen. The prospect of coming across a jaguar, or a beautiful snake or frog, or even an entirely new species, gives me an unparalleled rush of excitement.
It was in November 2023 that this dream became a reality. I embarked on an eight-month trip to Tambopata in the Peruvian Amazon, starting my work with Fauna Forever. The organisation was founded in the 1990s by conservation biologist Chris Kirkby to help protect wild spaces worldwide, particularly in the Amazon. The team engages the local community in conservation efforts and conducts field research activities, such as caiman monitoring, camera-trap projects and bird surveys.
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Their efforts illustrate how biological monitoring can drive conservation efforts, contributing to the establishment of the Tambopata National Reserve in September 2000. This achievement safeguarded 2,750km² of forest from threats such as gold mining, deforestation and cattle ranching.
Catching a caiman
Pipi cuts the engine and, using Chris’s careful signals, glides the boat alongside a caiman, stopping about an arm’s length away. As we slow to a halt, buzzing mosquitoes swarm around us for a quick meal. With utmost concentration, Chris crouches into a catching position.
He slowly extends his hand above the reptile, pauses then – splash! He plunges his hand into the water, aiming for the caiman’s neck. Securing his hold on the animal, he pulls it out. “A juvenile white caiman,” he states, “about a year old”. Its pale colour helps with identification.
This is my first close-up look at a wild caiman and I’m in awe: its eyes, tiny crystalline white teeth and armoured skin are beautiful and detailed. I’ve long been fascinated by caimans and all crocodilians. These animals reached evolutionary perfection millions of years ago and their unchanged shape since the time of dinosaurs reflects this.
Perfectly adapted to their semi-aquatic lifestyle, only their eyes and nostrils emerge ever so slightly from the water’s surface, rendering them invisible to prey. Their streamlined bodies and powerful tails make them excellent swimmers, and their pressure receptors can detect prey such as fish in the murkiest of waters and on the darkest of nights. One particularly amazing adaptation is their palatal valve, which allows them to swallow prey underwater without choking.
Survival instincts
Caimans are true survivors. I’ve seen black caimans missing half their tails but still thriving. Most crocodilians are opportunists and eat a variety of prey, such as fish, insects, crustaceans, birds, snakes and larger mammals. They may have a sinister reputation, yet crocodilians are incredibly caring, arguably the best reptile parents.
On a previous field trip, I’d spotted a 1.2m-long white caiman in a jungle stream. A loud hiss warned me she had babies and I gladly backed away, knowing she’d defend them despite being smaller than me. Crocodilians embody both power and tenderness. They have thrived for millions of years and I hope will continue to do so for many more.
As we delve deeper into the night, more caimans are caught, including a large 1.7m-long adult. The final individual, a youngster of about 70cm, presents our biggest challenge. We approach but, just as Chris goes for the catch, the caiman vanishes, resurfacing among reeds. Moving closer might scare it off, so Chris decides to jump out of the boat. With a tally of nearly 300 caimans caught to date and thousands more monitored by sight, he has the experience and skill to make this call.
I wait, my heart racing. Chris sinks into reeds, shallow water and thick mud, and makes a swift movement. “Got it,” he shouts. He turns and I see a figure covered in mud with a caiman in one hand. “I’ll be showering fully clothed tonight,” laughs Chris.
Curious as to how it feels to catch a caiman, I ask what goes through his mind. “I’d imagine it’s like hunting,” he says. “It fulfils the same primordial instinct humans have to test themselves against animals. Except there’s a scientific purpose.”
Caiman conservation
Once a caiman is caught, the researchers gather data as quickly as possible to minimise stress to the animal. First, the species and its sex are identified. Then its health is assessed, and measurements such as body length and tail circumference recorded. The whole operation takes about 10-15 minutes in total.
Prior to release, each caiman is tagged with a microchip known as a passive integrated transponder (PIT). Data from repeated captures provides insights into growth rates, age and territoriality. Boasting one of the largest global databases of caiman recaptures, Fauna Forever has learned a great deal about caiman biology. “Better knowing a species biology allows for more informed conservation planning and choices,” says Chris.
One behavioural trait the organisation has learned is the high site fidelity of white caimans, who are often recaptured in the same area. This information could support future research into mercury contamination, a toxic by-product of gold mining in the Madre de Dios watershed. If caimans consistently inhabit the same area, analysing mercury bioaccumulation through nail samples could clarify the geographical distribution of this pollutant and the impact it is having on the caiman population. And since caimans are a common food source for Amazonian communities, assessing mercury levels is vital for evaluating the potential health risks from their consumption.
In the 1960s and 70s, the black caiman was in serious decline due to hunting for its skin. Populations are recovering well and the other two species aren’t currently at risk. However, long-term monitoring remains vital, as even abundant species can decline alarmingly quickly. The common passenger pigeon went extinct rapidly in the early 20th century. Had its population been properly monitored, the decline might have been noticed in time to act.
The dangers of catching caimans
Catching caimans is not easy and comes with obvious risks. I ask Chris about his thin neoprene gloves, which don’t appear to offer the slightest protection against sharp crocodilian teeth. “A caiman will bite right through these,” he says. “I wear them as they give me grip, so I don’t drop one and risk injuring us both.”
Chris has had his fair share of caiman-inflicted injuries. On one occasion, his wrist was gripped firmly by a caiman and ‘death-rolled’ three times, leaving a substantial scar. Some black caimans reach 5m in length and could inflict serious damage. But fatal encounters are rare, usually occurring when people swim at night – something to avoid in the Amazon.
Compared to their Australian and African cousins, the saltwater and Nile crocodiles, black caimans are less aggressive and do not actively hunt humans. Common sense is essential in crocodilian fieldwork though. When Chris once wrestled a 2.9m, 100kg black caiman, he had the support of four others to safely manoeuvre his quarry on to the bank. The most significant danger when monitoring caimans is the Tambopata itself, with its strong currents, whirlpools and changing tides. Chris experienced this first-hand when he was once swept off the boat and pulled beneath the surface. Had he not been wearing a lifejacket, he likely would have drowned.
We have spent four hours on the water, and Chris has caught eight caimans, all of which have been monitored. Our work is done for the night, so we head back upriver to camp. Later on, safely cocooned under my mosquito net, I’m resolute in the belief that we can’t give up on the fragile Amazon. Fauna Forever’s work – and the dedication of individuals such as Chris – offers hope for this very special ecosystem. Now, more than ever, we must persevere.
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Main image: a young dwarf caiman (Paleosuchus trigonatus) at night in a rainforest stream. Credit: Louis Guillot
