The chimpanzees of Comoé National Park, Ivory Coast, have come up with a nifty way to stay hydrated, developing sticks to dip into tree holes and soak up water for consumption. The behavior was observed by researchers working to conserve the endangered species, who say it is the first time that this kind of water dipping has been found to be widespread in chimpanzee populations.
That chimpanzees are rather handy with tools is well-known and has intrigued scientists for decades. Recently, some researchers even filmed chimps in the Republic of Congo actively teaching their young how to take a purpose-built probe to a termite mound and pull out the little critters for dinner.
Another branch of chimpanzee tool-use is so-called "fluid-dipping," where the animals use specially crafted stick tools to dig around in tree holes for honey and water. Honey dipping was known to be quite widespread across Africa, but dipping for water has only been observed in a handful of cases, and never in a habitual or customary way.
But now researchers from the Comoé Chimpanzee Conservation Project have spotted widespread water-dipping behavior in populations across the Comoé National Park. Using camera traps to film chimpanzee activity, the team recorded adults, juveniles and infants in three different communities chewing sticks to loosen the fiber and improve their absorption capacity, before dipping for water.
Inspection of the dipping tools revealed that length, diameter and brush length were different to the sticks used for honey, and that the water-dipping variety had consistently longer and thicker brush tips. And because the behavior was widespread throughout different age groups, sex classes and communities, the researchers say that cultural transmission is a possibility.
The researchers are unsure whether the technique actually improves access to water. Interestingly, while the behavior was observed only during the late-dry season, the chimps always had access to other water sources like rivers and pools where no tools are needed, so ... maybe they just enjoy the challenge?
You can see them in action in the video below, while the research was published in the American Journal of Primatology.