Tracking Black-Faced Night Monkeys in Peru with HIKMICRO

“As nocturnal mammal researchers working in tropical rainforests, being able to 'see' in the dark is essential. The HIKMICRO HABROK and HABROK Pro give us that ability. Until recently, nocturnal animals, particularly those living in the rainforest canopy, were little studied because the only way to observe them was from the ground using bright spotlights. Inevitably, this method disturbed the mammals, making it difficult to learn about their natural behaviour,” said Trevor Hughes, a member of a wildlife research team from the UK.

With the development of thermal and infrared optical technology, things have changed. We now have tools that allow us to observe mammal behavior without disturbing them. Our project has pioneered a new method for studying arboreal nocturnal mammals in the rainforest. Working in Panama, Central America, and Peru, South America, we have been using a tree stand, a chair strapped to a tree trunk, as an elevated platform 10–20 meters above the ground to observe mammal activity using the HABROK 4K HQ35L. This year, we also tried the HABROK Pro HQ50L.

The thermal imaging quality of both models allows us to scan the entire forest from ground to canopy in search of mammals. The video capability lets us record valuable data directly from the same unit, eliminating the need for a separate video recorder. Once we have clear thermal views, we can switch at the press of a button to IR Optical mode to reveal more detailed images of the animals, enabling better identification. Having all these capabilities in one unit has revolutionized our ability to observe mammal activity in the treetops at night.

One such little-studied mammal is the Black-faced Night Monkey (Aotus nigriceps). This primate is only active after dark, making it very difficult to study in the wild. Luckily, they live in small family units and have small home ranges, so if we choose our site well, we can observe the same family each night as it goes about its business.

With the help of the HABROK and HABROK Pro, we have gotten to know several families this season and have begun building a video record of behavior. One particular family consists of an adult pair, an infant still being carried, and a juvenile. We were able to observe them as they moved around our platform in a circumference of roughly 80 meters in any direction.

It is the male who carries the infant, but we have noticed that the family always stays within a few meters of each other, constantly making low-contact calls to stay in touch. The rainforest can be very dark, with weak moonlight hardly penetrating the leafy canopy; however, Night Monkeys have huge eyes that can make use of even the faintest light. This was evident as we watched them move with dexterity, leaping and jumping at speed, even with an infant on their backs.

We found it fascinating to watch this family's interactions with other mammals, including ourselves. Our platform at this site is 21 meters high, on the main trunk of the tree, just below the leafy canopy that fans out another 10 meters above. On our first night of observations, the family crossed into this tree, giving us superb close-ups. However, despite using thermal imaging, which emits no light, we were still detected, most likely because of noise we made while moving to follow the monkeys, or perhaps our scent.

At this point, they were only about 5 meters from us. The family paused, all facing us, and made high-pitched alarm calls. Slightly agitated, they moved to a safer distance of around 10 meters, still watching us intently and sometimes repositioning to get a better view. All other activity ceased as they assessed the threat. However, within eight minutes, they decided we were no threat and slowly returned to feeding and foraging directly above us. We were able to record this interaction thanks to the HABROK.

We may have disturbed the monkeys with our noise and smell, but had we shone a bright white light on them, we would likely have temporarily blinded their sensitive eyes and caused them to flee. Instead, with no unnatural bright lights to scare them, they accepted our presence and resumed normal activity. Experiences like this strongly advocate for the use of thermals for night-time wildlife watching. It is the ethical way forward for both researchers and enthusiasts.

Find out more about Trevor and his team’s survey on nocturnal arboreal mammals： https://link.springer.com/article/10.1007/s13364-026-00845-1 

*Before purchasing any thermal or digital day & night vision device, please make sure you adhere to the local ledislation and only use it when it is allowed. Our ambassadors come from various countries and travel a lot, which allows them to test different devices. We do not encourage or support the illegal use of our devices in any events.