The enigmatic world of mountain gorillas – flatulence, vocal highs, and all – has been revealed through the use of “groundbreaking” lifelike animatronics embedded in the wild to record the daily life of gorillas.

The footage is part of the BBC-PBS miniseries Spy in the Wild 2 that aired in late April. Throughout the four-part production, filmmakers at John Downer Productions developed a complex process that employs lifelike robots made to resemble wild animals. Dozens of these “ultra-realistic animatronic” spy robots went “undercover in the animal world” to capture unique animal behavior up-close and personal. Spy gorilla, one of the “stars of the show,” is a good example of how the creators set out to make the novel robots.

“Firstly, we need to work out what spy animals would be best to film the animal. So, for example, it would not be a good idea to make a spy Silverback Mountain gorilla, as this could be seen as too much of a threat to the real mountain gorillas. Therefore, we went with a baby gorilla,” explained filmmaker Matt Gordon in a blog post.

The result was a collaboration between producers, who are also biologists and zoologists, to make the creatures as realistic as possible – starting with the eyes. Mountain gorillas learn about each other by staring into one another’s eyes but looking a male silverback gorilla in the eyes can serve as a threat, prompting the large animal to fight any challenger, according to Rwanda Gorilla. That’s why the spy gorilla was created with the ability to close and move its eyes, as well as avert his gaze.  

When spy gorilla was embedded within its adopted family of wild gorillas, the little robot “witnessed some of the family’s most intimate moments like eating, singing, and flatulating.” The result represents the first-time mountain gorillas have been caught singing on camera – but not the first time it had been observed. A 2016 study published in PLOS ONE documented “food-calling” behavior in gorillas, which describes the great apes making vocal sounds when gathering and eating food, varying pitches and durations depending on the quantity and quality of the food and the audience. The study authors write that the discovery provides an interesting viewpoint on the evolution of language and vocal communication, especially our own. On the other hand, the filmmakers call it a “chorus of appreciation.”

Perhaps more showing of the great apes’ appreciation of the 40 pounds of greens eaten every day is the bellowing farts that erupt throughout the episode. According to the voiceover, the gorillas live in a “semi-permanent state of flatulence.”

The Tropics episode also showcases a hippo pod, the “secret world” of pygmy forest elephants, and shows us what life is like inside a flying fox nursery.