Chimpanzees have been caught on camera using fishing rods to gather algae to eat in Bakoun, Guinea.
The chimps were observed engaging in this unusual behaviour at a temporary research site set up as part of the Pan African Programme to investigate chimpanzee culture and behaviour in the wild.
A collection of long sticks strewn across riverbanks and near pools led researchers working on the programme to believe that the chimps were using them as tools.
Site manager of the programme, Anthony Agbor, decided to place camera traps in these areas to see what the chimps were doing with the sticks.
Ammie Kalan of the Max Planck Institute for Evolutionary Anthropology and co-author of the study published in the American Journal of Primatology, says that the tool-use appears to be quite different from what is known from long-term chimpanzee-observation sites in Guinea.
"All age and sex classes of Bakoun chimpanzees were seen in the camera trap videos to successfully fish for algae in a river, stream or pond using woody branches or twigs as fishing rods," Kalan says. "Some Bakoun tools were more than 4m long."
A new way of studying chimps
Wild chimps have been under observation at long-term research sites for almost 60 years – but opening up research into new, temporary observation points has led to discoveries of new behaviours. "The PanAf project represents a new approach to studying chimpanzees and will provide many interesting insights into chimpanzee demography and social structure, genetics, behavior and culture," says Hjalmar Kuehl of the Max Planck Institute for Evolutionary Anthropology and the German Centre for Integrative Biodiversity Research.
Previous research by the PanAf group includes documenting unusual stone-throwing behaviour among the chimpanzees.
Chimpanzees have also been seen collecting algae at Bossou in Congo. However, at the Bossou site the algae collects at the water surface rather than growing at the bottom of stream beds as it does in the Bakoun site in Guinea.
"The ecology of the particular algae growing at each site may drive the types of tools necessary to harvest the algae," says Christophe Boesch, also of the Max Planck Institute for Evolutionary Anthropology. "We suggest that the algae probably provide an important nutritional benefit to the chimpanzees at Bakoun, especially during the dry season when chimpanzees were observed to fish algae for up to an hour at the same spot."