Capuchin monkeys are well-known for their tool-using abilities. Give a capuchin a nut and it’ll quickly balance it on its flattest side and smash it with a rock to get at the tasty nut guts. They don’t just use tools – they use them really well. But a wild female bearded capuchin in Serra da Capivara National Park (SCNP) in Brazil recently took tool use to a new level of creativity when she was recorded utilising a stick ... to pick her nose.

Researchers watched in surprise as the New World monkey, nicknamed Acacia, slipped a stick up her nostril multiple times before following up with a sneeze. According to observations the researchers outline in a recent paper, she tried several sticks and even a flexible grass-like stem. After each dig, she examined her nose probe (and did a quick taste test) just to make sure the tool had done the job. She also used the sticks to pick at her teeth (if you’re an eligible capuchin bachelor, Acacia is probably not a monkey you want to take home to meet your parents).

While it’s not unusual to see males of the species wielding sticks to poke around in rock crevices in search of lizards or to investigate a beehive for honey, the blokes usually keep their sticks out of their noses (or perhaps they just prefer to do their booger removal in private). Female capuchins, however, are rarely seen using probe tools at all, and aside from a report in 1999 of a flu-ridden male chimp at a research site in East Africa cleaning his nose with a stick, this sort of nose-picking behaviour is unheard of.

“No adult female [capuchin] has been seen to use a probe tool for foraging, and the only prior instance of an adult female using a stick tool was when one capuchin used a stick to poke the individual she was grooming,” the researchers note.

The researchers are notching this up as a quirky character trait specific to Acacia, although they do suggest that the behaviour could have been an attempt by the monkey to clear her nasal cavity. Teeth-picking behaviour is a little more common in primates, so they surmise that the purpose here was probably relieving discomfort or dislodging an irritant.

Header image: Luciano Marra