In another of what is becoming an increasing number of specific studies, chimps in one group of chimps in the Congo have learned to modify their sticks to greatly increase the amount of food (termites in this case) that they are able to collect. This recent study appears in Biology Letters.
The lead researcher Crickette Sanz, from the Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany, said: "They have invented a way to improve their termite-fishing technique."
Dr Sanz told the BBC: "We found that in the Goualougo Triangle in the Republic of Congo, the chimpanzees were modifying their termite-fishing tools with a special brush tip."
To make their rods, the chimps first picked some stems from the Marantaceae plant and plucked off the leaves.
"They then pulled the herb stems through their teeth, which were partially closed, to make the brush and they also attended to the brush by sometimes pulling apart the fibres to make them better at gathering the termites," Dr Sanz added.
Further research revealed that a stem with a frayed tip collected 10 times more termites than a pointed probe.
Dr Sanz said: "The chimps seem to understand the function of the tool and its importance in gathering termites."
So far, the team have only found this behaviour in chimps in the Goualougo Triangle.
The apparent absence of this in populations in eastern and western Africa suggests that it is not an innate skill found in all chimpanzees.
Instead it seems that the Goualougo primates are learning the crafting techniques from other chimps.